Radon-resistant new construction is a good starting point, but it does not remove the need to understand how the home actually performs after move-in. This page answers common questions about new builds, builder claims, subdivision differences, passive pipes, sump details, and why one home can test differently from another nearby home. Homeowners can use it to understand the difference between a rough-in and an active mitigation system, what testing can show, and why the final decision should be based on the actual house. American Radon Systems can review the mitigation side, explain whether the passive components are useful, and activate or adapt the system if readings point that way.
Yes, they absolutely can. Radon comes from the soil under the foundation, and that soil doesn't care how old or new your house is. A brand-new build sitting on high-radon ground can test just as high as an older one nearby. New construction doesn't automatically mean lower radon.
Question linkIt means the builder installed features designed to make it easier to reduce radon - not that radon is already controlled. "Radon resistant" is a starting point, not a finish line. You still need to test after you move in, and if levels are elevated, you activate or add to that system.
Question linkNot necessarily. Some new homes test fine, others test high - it really depends on the soil and geology under the specific lot, not the age of the house. The main advantage of new construction is that it's often easier and cheaper to address radon because the builder may have already roughed in a system for you.
Question linkActually, tight construction can work against you with radon. When a house is sealed up well, there's less natural air exchange, which means radon that does enter has fewer ways to escape. A tightly built home isn't immune - it's sometimes worse if the underlying radon source is strong.
Question linkRadon levels can vary a lot lot-to-lot even within the same subdivision. The geology under each specific lot matters - how the soil drains, where natural rock formations sit, local pressure differences under the slab. Two houses side by side can legitimately test at very different levels. That's why testing your specific home is the only way to know.
Question linkThat's not accurate. Illinois building code doesn't warranty low radon levels, and "built to code" doesn't mean tested and confirmed. Illinois is actually in a high-radon zone for much of the state. Testing is how you know what's actually happening in your specific home - code compliance is a separate thing.
Question linkYes. "Low radon area" is a generalization based on regional geology, not a measurement of your home. Plenty of homes in lower-risk zones test elevated, and the only way to confirm your actual levels is a test. It takes a few days and isn't expensive - don't skip it based on regional averages.
Question linkAs soon as you can get into closed-house conditions - which typically means windows closed, HVAC running normally, living in the home or at least having it in occupied mode for 24-48 hours before and during the test. Many people test in the first few weeks of move-in. The sooner you know, the sooner you can act if needed.
Question linkThe test itself works the same way. The main difference is that new homes with RRNC features may have specific recommendations about whether the passive system should be running or not during the test. Ask your radon professional or check with the builder about what configuration the system should be in when you test.
Question linkYou can, but the results won't be very meaningful until the home is complete, closed up, and in occupied-like conditions. An unfinished home with open doors, no HVAC running, and construction traffic doesn't reflect what you'll actually experience living there. Wait until it's done and then test in normal living conditions.
Question linkA pre-closing test can give you useful information, but make sure it was done under closed-house conditions and done by an independent party - not just the builder's crew. Ideally, you'd have your own test done or hire an independent tester. Some builders are completely above-board about this; others have a conflict of interest.
Question linkThe EPA says levels between 2.0 and 4.0 pCi/L are worth considering mitigation - the risk is lower than above 4.0, but it's not zero. Whether 2.8 is something you want to address is a personal decision. If the home already has a passive RRNC stub-out, adding a fan is usually straightforward and can bring that number down further.
Question linkThat's a smart move. A radon test contingency gives you a clear path to mitigation or renegotiation if levels come back high. Not all builders will agree to it, but it's worth asking. At minimum, know what you're walking into before you close.
Question linkIt's not unusual to discover this after the fact - a lot of people don't test until something prompts them to. The important thing is you have the number now. At 6.2 pCi/L, the EPA recommends fixing it, and the fix is very doable. Give us a call and we'll walk through what a mitigation system looks like for your house.
Question linkRadon risk varies by specific location, not just by general region. Moving to a different part of the county might mean higher or lower risk - you'd need to test to know. Don't assume geography protects you without actually measuring.
Question linkThat's likely well-intentioned, but builders aren't always doing systematic post-occupancy radon testing on all their homes, so the statement may not be based on solid data. You can appreciate the track record while still testing your own home - they're not mutually exclusive.
Question linkWinter is often considered the most revealing time to test because homes are closed up more and the temperature differential between indoors and outdoors tends to draw more soil gas in. Even so, testing any time under closed-house conditions gives you useful information. If your home will be ready in summer, don't wait until winter - test when you can.
Question linkAsk whether they're including RRNC features and which ones - specifically the sub-slab depressurization layer, the vertical pipe chase, and a stub-out in the attic or outside. Ask whether it's passive or active. Ask if they'll do a test after completion. And plan to do your own independent test after you move in to confirm the numbers.
Question linkIllinois doesn't universally require RRNC statewide, but many builders include it as a standard feature or because the local jurisdiction requires it, or simply because it's become industry best practice. Either way, the presence of those features is good - just remember to test and confirm they're actually keeping levels down.
Question linkRRNC stands for Radon-Resistant New Construction. It's a set of features built into a home during construction specifically to reduce the entry and buildup of radon. The core idea is to make it easier - and cheaper - to manage radon before the home is finished rather than having to retrofit everything later.
Question linkThe standard RRNC system has a few main pieces: a gas-permeable layer under the slab (gravel or aggregate) so air and radon can move freely below the concrete, a heavy plastic sheeting vapor barrier over that layer, a pipe that runs from below the slab up through the home and out through the roof or walls, and an electrical junction box near the pipe in case a fan needs to be added later. Some builders also seal floor-to-wall joints and other openings.
Question linkAsk them to walk you through specifically what was installed: Is there a gas-permeable layer under the slab? Was a vapor barrier installed? Is there a vertical pipe from below the slab through the house and out the roof? Is there an electrical outlet near the pipe in the attic? Those are the four main elements. If all four are there, you have a proper passive RRNC system.
Question linkNo. RRNC reduces the likelihood of high radon and makes the system easy to activate, but it doesn't warranty any specific level. Whether a passive RRNC system keeps levels low depends on the geology under your specific lot, how tight the slab is, and how strong the natural draft is through the pipe. You test to find out where you actually land.
Question linkA passive system relies on natural air pressure differences to draw soil gas up through the pipe and out of the house - no fan, no electricity required. An active system adds a fan to that pipe, which creates a consistent vacuum under the slab and is much more reliable at keeping levels low. Passive is better than nothing and easy to activate, but active is significantly more effective.
Question linkCost and simplicity - a passive system is cheaper to install and doesn't require wiring a fan into the electrical system from day one. The idea is that many homes won't need the fan, so you install the rough-in (passive) and only add the fan if testing shows you need it. If every home needed a fan, builders might as well install active systems universally.
Question linkTest first, then decide. If your post-occupancy test comes back below 2.0 pCi/L, the passive system is doing its job and you may not need to add a fan. If you're between 2.0 and 4.0, adding the fan is worth considering. If you're at 4.0 or above, the EPA recommends fixing it - and adding a fan to your existing passive system is the path forward.
Question linkIllinois doesn't have a statewide mandate requiring RRNC for all new construction, though some municipalities or counties may have local requirements. Many builders in the region include it as standard practice because Illinois is largely in a high-radon zone and it's become common industry behavior. Check with your local building department if you want to know what your specific jurisdiction requires.
Question linkAdding RRNC features during construction is relatively inexpensive compared to retrofitting a mitigation system later. The cost difference during construction is modest - mostly the aggregate layer, vapor barrier, and pipe rough-in. Retrofitting after the fact typically involves more labor, disruption, and expense. The economics almost always favor doing it during the build.
Question linkYes. A standard sub-slab depressurization (SSD) mitigation system can be installed in an existing home - the contractor drills through the slab, inserts a pipe, and runs it out through the wall or roof. It's more involved than activating an existing passive system, but it's very doable. Most radon mitigation in Illinois is exactly this kind of retrofit work.
Question linkNot typically in a meaningful way. Some insurers may view it as a positive feature (less risk of a major mitigation project), but there's no standard insurance credit or penalty tied to RRNC. It's worth asking your insurer, but don't expect it to dramatically change your premium.
Question link"Radon ready" is sometimes used interchangeably with passive RRNC, but it can also mean the builder only did partial prep - maybe just the pipe chase without the gravel layer or vapor barrier. Ask specifically what was installed and cross-reference it with the standard RRNC components. The terminology isn't perfectly standardized across builders.
Question linkThe point is that RRNC makes the solution much simpler if testing shows a problem. Instead of drilling through your slab and figuring out where to route a pipe after the fact, you already have the infrastructure in place. You're paying for optionality and lower retrofit costs - not a warranty of low radon.
Question linkThe same basic principles apply - gas-permeable layer, vapor barrier, and pipe - but the execution and access points differ. A slab home without a basement has the pipe running up through the interior walls or exterior. A basement home typically routes through the basement and up. Both can be effective; the design just has to match the foundation type.
Question linkThey're describing the passive mode - natural pressure differences and thermal stack effect draw soil gas up through the pipe and out of the house without a fan. This works reasonably well in many conditions, but it's not as reliable or consistent as an active fan-driven system. It's a starting point, not a finished solution.
Question linkYou can look for the main components - the pipe coming up through the mechanical space or basement and exiting through the roof or wall, and an electrical outlet near the pipe for a future fan. But the only way to know if the system is actually keeping radon levels in check is to test after move-in. Visual inspection confirms the components exist, not that they're performing.
Question linkA capped pipe doesn't do much. The system works by allowing air movement - a capped pipe just sits there. Some builders install a cap temporarily during construction to keep debris out, which is fine, but it needs to be uncapped before occupancy. If you find a capped pipe, ask the builder whether it's meant to be open and confirm the system is properly set up before you move in.
Question linkYes, as a side benefit. Sub-slab depressurization is effective against other soil gases like methane or volatile organic compounds that might seep through the foundation, though radon is the primary target for residential applications. This is rarely the reason homeowners ask for RRNC, but it's a real secondary benefit.
Question linkThe EPA has published guidance documents (like the Builder's Guide) that describe what components and installation practices constitute a proper RRNC system. When a builder says they meet EPA guidelines, they should mean all the main components are there and installed correctly. It's worth asking them to be specific about which EPA guidance they're following.
Question linkAn upgraded package might include: a larger-diameter pipe for better airflow, pre-installed fan with wiring already in place (making it truly active from day one), pressure monitoring ports, sealed sump crock cover, and comprehensive sealing of all potential radon entry points including cracks, utility penetrations, and the floor-wall joint. The more complete the sealing, the more effective the system.
Question linkA stub-out (sometimes called a rough-in) is the pipe that's been installed in your home as part of the passive RRNC system, typically ending in the attic or just outside the roofline. It's the pipe that a fan can be attached to if you need to activate the system. Think of it as the infrastructure waiting to be used if your radon test says you need it.
Question linkIdeally it runs from below the slab, through the interior of the house (inside conditioned or semi-conditioned space), and exits through the roof. Running it inside keeps the pipe warmer, which improves natural draft in a passive system. If it's routed outside through an exterior wall, it can still be activated with a fan, but the performance of the passive mode will be weaker.
Question linkIt's not ideal. A stub-out in the garage attic means the pipe exits into a space that isn't heated and conditioned the same way, which reduces the thermal stack effect that makes passive systems work. It can still be activated with a fan, but you'd want to make sure the system design is sound. Ask your builder whether the pipe can be rerouted, or test first and then decide.
Question linkAfter testing. There's no point in running a fan and consuming electricity if your passive system is already keeping radon levels comfortable. Test under normal passive conditions first, then decide based on the results whether activating the fan makes sense.
Question linkThat's something a radon mitigation professional handles - they'll assess your sub-slab communication (how freely air moves under your slab), pipe diameter, and layout to select the right fan. Using the wrong fan size can make the system less effective or create pressure issues. This isn't a DIY sizing situation.
Question linkTechnically you can buy a fan, but the installation involves more than just plugging a fan onto the pipe. You need to confirm sub-slab communication is adequate, the system is creating appropriate negative pressure under the slab, connections are sealed, and the system is properly vented to the exterior. Improper installation can look like it's working while doing very little. A professional installation comes with a manometer for monitoring and proper verification.
Question linkYes - the pipe should terminate above the roofline, clear of windows and doors, so the exhausted soil gas (including radon) doesn't re-enter the home. If the pipe just ends inside the attic, you're releasing radon into the attic space, which isn't useful. Check that it exits properly through the roof.
Question linkA U-tube manometer is a simple pressure gauge - a small tube filled with liquid that shows whether the pipe is maintaining negative pressure under the slab. If the liquid in the tube is unequal on both sides, the system is working. If it's level, something may have changed (fan failure, blocked pipe). Not all passive RRNC systems include one, but they're common on active systems.
Question linkThat outlet is there specifically for a future radon fan. When someone needs to convert the passive system to an active one, they just mount the fan on the pipe and plug it in - no rewiring required. It's a smart rough-in feature and means activation is quick and clean.
Question linkBuilders sometimes cap the stub-out during construction to keep debris from falling in. Before or after occupancy, that cap should be removed so the system can function properly. If you're in a completed home and the cap is still on, take it off and then test to see how the system performs passively.
Question linkNot necessarily - larger homes with complex slab areas or disconnected sub-slab zones sometimes need multiple pipe locations to achieve adequate depressurization across the full footprint. Two pipes each with their own fan, or two pipes combined into one fan, are both viable configurations. It depends on the layout of your specific foundation.
Question linkIt creates a gas-permeable pathway - essentially a network of small voids that allows soil gas (including radon) to move horizontally below the slab rather than pushing straight up through it. When the pipe creates suction (or natural draft), it can draw radon from a wider area because the gas can travel laterally through that gravel before it gets to the pipe. Without it, you'd only be drawing from directly under the pipe location.
Question linkSand is less permeable than gravel and doesn't create as free-flowing a pathway for soil gas. Coarse gravel is the preferred material for RRNC because of its higher permeability. If only sand was used, the system can still work but may be less effective, especially in passive mode. This is worth asking your builder about if you're still in the construction phase.
Question linkThe vapor barrier - typically a thick polyethylene sheeting - goes on top of the gravel layer and under the concrete slab. It reduces the amount of moisture and soil gas that migrates directly up through the slab. It's not a perfect seal (concrete still has small pathways), but it significantly reduces the passive movement of radon into the living space.
Question linkYes, significantly. Every pipe, conduit, and utility penetration through a slab is a potential radon entry point. Sealing them with polyurethane caulk or expanding foam reduces those pathways and makes the overall system more effective. Builders who take this step are doing a more thorough job than those who just install the pipe and gravel.
Question linkEPA guidance typically recommends a minimum of 3-inch diameter pipe, with 4-inch being common and preferred for better airflow. A larger pipe creates less resistance and allows the system to work more effectively, whether in passive or active mode. If your builder used 2-inch pipe, it may be less effective and worth flagging.
Question linkPVC (schedule 40) is the standard material for radon mitigation and RRNC piping. It's the right call - durable, easy to seal, and appropriate for the application. You might also see ABS in some installations. Either is fine as long as joints are properly glued and sealed.
Question linkThe sump crock (the pit where your sump pump sits) is often a direct pathway for soil gas to enter the basement because it's an opening into the ground below the slab. A proper RRNC or mitigation system includes a sealed cover over the sump crock with appropriate fittings for the pump discharge and electrical pass-throughs. Without it, radon can bypass the rest of your mitigation system.
Question linkFloor drains can also be a pathway for soil gas, though they're typically less significant than an open sump crock. If your radon levels are elevated despite a working mitigation system, the floor drain is worth looking at. A plumber's test ball (a removable rubber plug) can temporarily block it to check if it's contributing.
Question linkAfter you've moved in and the home has been in normal living conditions for at least a couple of weeks - windows closed most of the time, HVAC running normally. Testing before the home is occupied and in lived-in conditions won't give you the most accurate picture of what you'll actually be exposed to day to day.
Question linkYou can accept it as useful data, but seriously consider having an independent test done as well. A builder has an incentive for the result to look good, not necessarily a bad incentive, but it creates a conflict of interest. An independent test from a licensed tester gives you cleaner information. Use both if you can.
Question linkA short-term test with a charcoal canister typically runs 48-96 hours (two to four days) under closed-house conditions. A long-term test (alpha track) runs 90 days to a year and gives you a better picture of average annual exposure. For initial testing of a new home, a short-term test under closed-house conditions is a reasonable starting point.
Question linkWhen testing with a passive system, you generally test with the system in its normal passive state - don't block the pipe or alter it during the test. The goal is to see how the home actually performs with the system as installed. If you want to know how it performs without the passive system, that's a separate experiment.
Question linkPassive RRNC is a rough-in, not a promised outcome. It depends on natural draft, which varies by temperature differential, wind, and the specific geology under your lot. At 4.1, the EPA recommends fixing it - and the good news is you already have the pipe in place, so adding a fan to activate the system is straightforward and much less expensive than starting from scratch.
Question linkThe lowest livable level of the home is the standard placement for a radon test - that's where levels are typically highest and where you'd have the most meaningful exposure data. If your lowest level is a finished basement or walk-out basement, test there. Testing only on the main floor of a two-story home over an unfinished basement doesn't tell you the full picture.
Question linkIn the walkout basement level itself, in the lowest occupiable area. A walkout basement is still in contact with the soil and can still have elevated radon even though it has above-grade windows on one wall. Test at the lowest level you actually use or plan to use.
Question linkA year-long alpha-track test is ideal because it averages out all the seasonal variation. If you don't want to wait a full year, 90 days will capture at least one full seasonal change and gives a reasonably representative picture. Either is more reliable than a single 48-hour test for making long-term decisions.
Question linkYes. Even if that's accurate, radon can vary lot to lot within the same subdivision. The only test that tells you about your home is the one in your home. It's cheap, low-effort, and the consequences of skipping it - not knowing your levels for years - are much worse than the small amount of time it takes.
Question linkAfter you return and have been living in the home normally for a bit is the better option. You want the home in occupied conditions (normal HVAC operation, normal occupancy patterns) for at least a few days before and during the test. An empty house for two months doesn't replicate real living conditions.
Question linkYes - closed-house conditions mean keeping windows and doors closed (except for normal entry/exit) and HVAC running normally throughout the test. This applies to all short-term radon tests, new or old construction. Conditions that don't match how you actually live will give you a less useful result.
Question linkAt 1.2, you're well below the EPA's 4.0 pCi/L action level, and below the 2.0 level where they suggest considering action. That's a reassuring result. Keep the number and if you renovate or do significant work on the foundation or basement in the future, it's worth testing again afterward to make sure things haven't changed.
Question linkYes, in most cases adding a fan to an existing RRNC stub-out is less expensive than a full retrofit. The rough-in work is done - the sub-slab layer, vapor barrier, pipe, and electrical outlet are already there. A full retrofit on a home without RRNC means drilling the slab, routing a new pipe, potentially fishing it through finished walls, and adding electrical. The RRNC investment during construction pays off here.
Question linkTest first. If your radon comes back at 4.0 pCi/L or higher, yes - activating it (adding a fan) is the right move. If it comes back between 2.0 and 4.0, you have a decision to make that involves your comfort level with the risk. If it's below 2.0, the passive system is likely doing enough on its own for now.
Question linkThat's exactly what it was designed for. The passive stub-out is the rough-in stage, and adding a fan converts it to an active sub-slab depressurization system. A radon mitigation professional connects the fan to the pipe, plugs it into the outlet that should already be there, and seals everything properly. It's a relatively quick job when the infrastructure is already in place.
Question linkIt's worth considering, especially if you're in an area with a history of elevated radon. The cost difference between passive and active during construction is modest, and you'd move in knowing the system is already running and effective rather than waiting to test and potentially retrofitting later. If you're in a high-radon region and the price is reasonable, it's a solid choice.
Question linkThe main indicator is the manometer gauge on the pipe - if the liquid levels are unequal (showing negative pressure), the fan is pulling. You can also feel airflow near the fan discharge pipe outside. Many modern radon fans have indicator lights or come with a visual warning device that changes color if pressure is lost. Check it periodically.
Question linkSome low-level fan hum is normal. Radon fans run continuously and typically produce a modest, steady sound. If the noise is loud, rattling, intermittent, or has changed from what it used to be, that's worth checking - it could indicate the fan is wearing out, something is loose, or debris got into the system.
Question linkA quality radon fan installed in a new home's RRNC system typically lasts many years - most manufacturers rate them for a decade or more of continuous operation. They do wear out eventually, so it's worth checking the manometer periodically and replacing the fan if it fails. They're not expensive to replace.
Question linkIt's a low-maintenance system overall. Periodically check the manometer to confirm the system is maintaining negative pressure, listen for changes in fan noise, and visually inspect the exterior pipe termination to make sure it's not blocked. Beyond that, there's not much routine maintenance. If you're ever unsure whether it's working, a radon test will tell you quickly.
Question linkYes, it runs continuously. Radon can enter the home in any season, and turning the fan off seasonally defeats the purpose of having it. The electricity consumption is modest - comparable to a light bulb - so there's no meaningful reason to ever turn it off intentionally.
Question linkYes, periodic retesting is a good idea. The EPA suggests retesting every two years or after any major renovation or change to the foundation. Two years of continuous operation is a good milestone to confirm the system is still performing and radon levels haven't crept up due to seasonal, geological, or structural changes.
Question linkA buyer's agent will very likely request a radon test as part of the sale process regardless of the existing system. That's reasonable - they want to know the current levels in the home as-is. The active system is a selling point, and if it's been maintaining good radon levels, a test during the sale process should confirm that.
Question linkYes, before you put up walls and flooring. Finishing a basement - especially converting it to occupied living space - is one of the most important reasons to test. Radon levels in an unfinished basement give you a baseline; once you finish the space, the mitigation access points become harder to reach. Know the numbers before you build.
Question linkIt's not too late, but sooner is better. If you haven't started construction, test now in the unfinished basement. If you're mid-project, test as soon as you can in the lowest accessible area. If it comes back elevated, it's much better to address it while the space is still open than after you've put up drywall and flooring.
Question linkRadon at 3.5 pCi/L is below the EPA's 4.0 action level, but it's in the range where the EPA says the risk is real and worth considering mitigation. A sleeping area is long-duration occupancy, which increases cumulative exposure. At 3.5 with a bedroom being added, I'd seriously consider mitigation - especially since you'll be spending 8 hours a night down there.
Question linkIt's a smart time to do it. Contractors are already down there, the floor and walls are open or accessible, and routing a pipe and adding a fan is much simpler during a remodel than after everything is finished. If you're going to add living space, add radon mitigation in the same project.
Question linkThe radon source is the soil and sub-slab, which affects the whole basement footprint. A reading of 5.8 in one part of the basement means elevated radon is a whole-basement issue. At that level, the EPA recommends fixing it. Finishing more of the basement without mitigation would just be adding more occupancy to an already elevated-radon space.
Question linkYes. You're about to create a room people will spend significant time in - movies, gaming, watching sports. That's long-duration occupancy, which is exactly the scenario where cumulative radon exposure matters. Test first, mitigate if needed, and then finish the room with confidence.
Question linkAbsolutely - this is a good prompt to test. Neighbor's results give you useful information about the general geology in your area, but they don't tell you what's happening under your specific foundation. Get a test done. If you're using that basement regularly, you want to know your own numbers.
Question linkIf radon hasn't been tested yet, test before the insulation goes in. Spray foam or rigid insulation on the walls and floors can make later mitigation more complex. You want to know what you're dealing with before you seal everything up.
Question linkAt 4.8, you need mitigation. The partially finished space actually makes it a bit easier than a fully finished basement - there's still some access to the slab. A radon professional can evaluate whether they can work with the existing layout or whether it's better to do the mitigation work before the remaining finishing happens. Either way, address the 4.8 now.
Question linkIt can be. Finishing the basement changes the dynamics - you seal up more of the floor and walls, reduce natural air exchange in that space, and add long-term occupancy. Whether it actually raises the test number depends on how the finishing is done, but from an exposure standpoint, turning an unfinished basement into a living space you use regularly always increases the practical significance of whatever radon level is there.
Question linkSpray foam is an excellent air barrier, which is great for energy efficiency but can also trap soil gas that was previously escaping through minor wall cracks and the floor-wall joint. By sealing those pathways, you may have redirected radon that was diffusing out through the walls to accumulate in the living space instead. This is a common unintended consequence. The fix is sub-slab depressurization, not removing the foam.
Question linkTile on concrete doesn't provide meaningful radon reduction on its own. Concrete is porous, and tile laid over it with grout lines and adhesive doesn't create an airtight barrier. If radon is elevated, tile isn't the fix. Even so, tile doesn't typically make things significantly worse either - it's just not a mitigation strategy.
Question linkThere's no universal federal mandate for landlords to test or mitigate radon, though Illinois and local codes vary and some jurisdictions are strengthening requirements. Beyond the legal question, there's also an ethical one: if you're renting a space to someone who will live there full time, knowing and addressing radon levels in that space is the right thing to do. Test before you rent.
Question linkBedrooms are the most exposure-intensive rooms in the house because you spend around 8 hours there every night. A bedroom in the basement means sleeping in the area of the home with typically the highest radon concentration. Test before the conversion, mitigate if needed, and retest afterward to confirm levels are acceptable before anyone starts sleeping there regularly.
Question linkThe EPA would call 3.2 an "elevated" level worth considering - not an emergency, but not nothing either. For a bedroom where she'll spend 8+ hours every night, that sustained long-duration exposure is worth taking seriously. Adding mitigation when levels are 3.0-3.5 is a personal call, but for a child's sleeping space I'd lean toward addressing it.
Question linkYes. A mother-in-law suite is a full-time occupied space - likely with sleeping, long hours of daily use, and an elderly person (who may be more vulnerable to cumulative exposure effects). Test now, and if levels are at or above 2.0-4.0 pCi/L, strong consideration for mitigation before someone moves in is completely reasonable.
Question linkYes. If the garage slab is on grade over soil (which most garage slabs are), radon can enter from below just as it does in a basement. A converted garage turned into a bedroom, playroom, or home office becomes occupied space, and the radon dynamics from that soil-to-slab contact don't go away just because you added drywall and carpet.
Question linkAn ADU is essentially a full apartment with long-term occupancy - someone will be sleeping and living there full time. Test before you finalize the conversion. If radon is elevated, build the mitigation into the ADU project so you're not coming back later to fix it after the tenant has moved in. A mitigation system installed during the renovation is always easier than a retrofit in an occupied unit.
Question linkMitigate first, then outfit the gym. At 4.2, the EPA recommends fixing it - and a home gym is a high-occupancy, high-activity space where you're breathing heavily and doing long workouts. Elevated respiration during exercise increases radon intake. Get the mitigation in place before you start spending hours down there regularly.
Question linkAt 3.7, you're just below the 4.0 EPA action level, but in the zone where the EPA says the risk is real and worth considering. A home office where you work 8 hours a day is significant long-term occupancy. That's a personal decision, but I'd treat 3.7 in a daily-use workspace the same way I'd treat 3.7 in a bedroom - worth fixing.
Question linkChildren are generally considered more sensitive to environmental exposures because they have more years of future exposure ahead of them and their tissues are still developing. A playroom where kids spend hours daily is meaningful occupancy. Test before finishing, and seriously consider mitigation if levels are in the 2.0-4.0 range - don't wait until you're at 4.0+ when kids are spending significant time down there.
Question linkAt 5.1, you need to mitigate. The good news is the theater equipment doesn't prevent a radon system from being installed - the pipe typically goes through the slab in a utility area, not under your seating. A mitigation professional can usually find a path that doesn't disrupt the theater setup. Call someone out and get an assessment.
Question linkPossibly. Breaking through the concrete for plumbing rough-in creates new openings in the slab where soil gas can enter. If the plumbing rough-in left gaps around the pipes that weren't properly sealed, those are now pathways for radon. Sealing around all plumbing penetrations and testing again will tell you if that was the source of the increase.
Question linkIt's worth correcting now. Guest bedrooms might see less occupancy than a primary bedroom, but occasional guests still accumulate exposure during their stays, and if you're only using it occasionally the risk is lower - but not zero. Test to know your levels, and if they're elevated, address it before the next round of guests.
Question linkTest immediately if you haven't, and address it if levels are at or above 4.0 - and seriously consider it in the 2.0-4.0 range given the long daily exposure hours. A teenager in a basement bedroom is high-occupancy, young-person use - exactly the scenario where radon exposure over years matters most. Don't delay on this one.
Question linkAt 4.6, mitigation is what the EPA recommends - and a recording studio is a space you'll be spending long, absorbed hours in. The acoustic treatment you're adding (foam, panels) won't do anything about radon, but a mitigation system can be installed without disrupting the acoustics. Sort the radon first, then build your studio.
Question linkIt can. The sump pit is essentially a hole to the soil below your slab - an open pathway for soil gas. If your sump crock doesn't have a sealed cover, it can be a significant radon entry point. When getting a sump pump installed, also ask about a sealed sump cover, which is a standard part of radon mitigation anyway.
Question linkIt can temporarily during the work, and it can create a new ongoing pathway if the penetrations aren't properly sealed when the work is done. Make sure your contractor seals around any new pipe penetrations with appropriate caulk or foam. After the work is complete, a radon test will tell you if the levels changed.
Question linkIt's a very likely contributor. The sump pump installation disturbed the sub-slab soil and may have left the sump crock open or increased the connection between soil gas and your basement air. At 6.0 pCi/L, you need mitigation. The mitigation system will typically include a sealed sump cover as part of the design, which addresses that specific pathway.
Question linkInterior drain tile systems (like WaterGuard or similar) create a continuous channel around the perimeter of the basement that connects to the sump pit - which is essentially a direct highway for soil gas from the foundation into the basement. This is a known and common cause of radon increases after waterproofing. The fix is typically a sub-slab depressurization system that pressurizes the drain tile channel and sump pit, drawing soil gas out rather than letting it flow into the basement.
Question linkYes, but it's a solvable problem. The drain tile system you installed is now connecting soil gas pathways to your basement air via the sump pit. This is one of the more common causes of sudden radon increases after basement waterproofing. A radon mitigation professional who understands drain tile systems can design a solution that addresses the specific entry pathways. Call soon - don't live with 6.0+ while you figure it out.
Question linkExterior waterproofing work can disturb the soil around the foundation and temporarily change the pressure dynamics, but it typically has less impact on radon than interior drain tile work. After any major foundation work, testing is a reasonable precaution to make sure your baseline hasn't changed significantly.
Question linkFloor drains are potential radon entry points because they're open connections to the plumbing system and occasionally to soil below. Installing a floor drain with a proper trap that stays filled with water will reduce this pathway. A dry floor drain trap is an open channel for soil gas. Include sealing consideration in the plan.
Question linkCrack sealing can reduce radon entry from specific cracks, and it's a legitimate part of a comprehensive mitigation approach. However, it rarely works as a standalone solution because radon enters through many pathways - the floor-wall joint, penetrations, and the slab itself are all routes. Sealing cracks is useful as a complement to sub-slab depressurization, not a replacement for it.
Question linkTesting before gives you a baseline. Testing after the work is complete (and after plumbing penetrations are sealed) tells you whether the work changed anything. Given that you're opening the slab and disturbing the sub-slab layer, an after-test is definitely worth doing.
Question linkYes, definitely. Adding a sump pump adds a new potential radon entry point. Even if your mitigation system is running, the new sump crock may be bypassing it. Retest to confirm, and if levels have crept up, your mitigation professional can evaluate whether the sump crock needs to be integrated into the system with a sealed cover.
Question linkExterior French drains are less directly connected to your basement air than interior drain tile, so the impact on radon is typically smaller. Even so, any significant work around the foundation perimeter can alter subsurface drainage and pressure patterns. A post-project test is a reasonable precaution.
Question linkEpoxy coatings reduce moisture transmission through concrete, but they're not a reliable radon barrier. Concrete has micro-pathways that epoxy doesn't fully seal, especially under pressure from soil gas. Epoxy coating might have a modest effect on radon, but it's not a mitigation strategy. Don't rely on it as your fix.
Question linkRim joists are often minor radon pathways - gaps around the perimeter where the framing meets the foundation. Sealing them with spray foam can close those minor exhaust pathways, which sounds counterintuitive but means radon that used to slowly exit there now accumulates instead. It's a common unintended consequence of tightening a home. The fix is sub-slab depressurization, not removing the foam.
Question linkVery likely yes. Tighter homes allow less natural air dilution of indoor pollutants. Radon that previously diluted through air exchange is now accumulating. This is well documented - a well-sealed home with no ventilation strategy will typically see higher radon levels than the same home with more air leakage. At 5.0, you need mitigation. Sub-slab depressurization addresses the source; adding an ERV for ventilation can help with general indoor air quality.
Question linkRigid foam on the interior walls is mostly sealing pathways through the foundation walls themselves, which can have a mixed effect. If the walls were a significant radon entry route, sealing them may help or redirect - but it doesn't address sub-slab entry. Test after the insulation work to see where you stand.
Question linkAn ERV adds controlled fresh air exchange, which dilutes indoor radon to some degree. However, an ERV is not a radon mitigation system - it doesn't address the source. It may reduce levels somewhat as part of a whole-house approach, but if you have significantly elevated radon, sub-slab depressurization is still the right primary fix.
Question linkAbsolutely - this is an ideal time. You're already doing significant work, contractors are already in there, and you may have better access to the sub-slab layer than you'll ever have again. If you don't already have a mitigation system, building one into this project is much more efficient than coming back later.
Question linkNo. The new concrete pour for radiant heat is typically thin and bonded to the existing slab, which itself is still porous. Radon will find its way through the joint between old and new concrete and through the new pour itself. If radon was elevated before the radiant floor, it will still be elevated after. Test afterward and mitigate if needed.
Question linkNo. Rubber mat flooring isn't an airtight barrier, and even if it were, the edges and seams would still allow soil gas to pass. Flooring materials don't meaningfully reduce radon levels. If radon is your concern, the solution is sub-slab depressurization, not floor coverings.
Question linkA thicker slab can slightly reduce the rate at which radon diffuses through the concrete, but it's not a reliable mitigation strategy. The sub-slab pressure and soil gas concentration are the real drivers of radon entry, not just the slab thickness. If you want to make the new pour part of a mitigation strategy, coordinate with a radon professional to integrate a sub-slab layer and pipe before you pour.
Question linkAn egress window itself (closed, as it will be most of the time) doesn't significantly change radon dynamics. The installation process - cutting through the foundation wall and disturbing the soil around it - can temporarily affect things. Once installed and properly sealed around the frame, an egress window doesn't meaningfully increase or decrease radon levels.
Question linkThere may be a temporary disturbance during construction, but a properly completed egress window installation shouldn't cause a lasting radon increase. Seal around the window frame properly when it's done. If you want peace of mind, test six weeks after the project is complete to confirm levels are back to baseline.
Question linkYes, from the very start. The addition basement is new sub-slab contact with soil, and it may connect to your existing basement. Include RRNC features in the addition foundation design, or better yet, coordinate with a radon professional to plan a mitigation system that covers both the original and addition footprint together.
Question linkIf the sunroom will be used regularly (heated, occupied), the slab-on-grade contact with soil means radon can enter from below. Whether it's a significant concern depends on how the sunroom is constructed and how much time you spend there. If it becomes a year-round living space, treat it like any other room on a slab and test it.
Question linkCrawl spaces absolutely can have radon problems. The soil-to-air pathway in a crawl space can be more direct than through a concrete slab, especially if the crawl space is unencapsulated. If you're adding a crawl space or converting existing crawl space to living space above it, radon should be part of the conversation.
Question linkThis is a significant excavation project that dramatically changes the relationship between your home and the soil below. Radon levels should be assessed as part of the planning, and if you're pouring a new slab, RRNC features should be incorporated into the pour. Test after the work is complete and the space is closed up.
Question linkCrawl space encapsulation can reduce radon entry from the soil through the crawl space floor, especially when combined with proper sealing. In some cases it makes a meaningful difference. In others, the radon source is strong enough that encapsulation alone isn't sufficient and you need active sub-crawl depressurization. Test after encapsulation to see where you land.
Question linkSignificant sub-slab excavation disturbs the soil and essentially creates an open connection between the soil below and your basement air. At 7.0, you need to mitigate promptly. The excavation created a situation where radon entry is amplified. A mitigation professional can design a system appropriate for what the space now looks like.
Question linkIf the ADU will be directly above a garage on a slab-on-grade, the relevant question is whether radon entering the garage can migrate into the ADU above. This depends on how well the garage ceiling/ADU floor is sealed. Radon from the garage slab is a real concern if the barrier between the garage and living space above isn't airtight. Test, and involve a radon professional in the ADU design.
Question linkIf you're spending significant hours in there regularly, yes. A garage is on a slab over soil, and daily occupancy of an attached garage for a workshop means meaningful cumulative time in a space that could have elevated levels. Test it. If levels are elevated, a mitigation system for the garage space is very doable.
Question linkYes, especially for the finished room above. If people will sleep or spend extended time in that upper room, plan for the possibility that radon from the garage slab below could affect it. RRNC features in the garage slab are relatively inexpensive during construction and much harder to add after the fact.
Question linkThe bonus room over the garage sits above a slab, and radon from that slab is a potential concern. Radon levels in this type of space are often lower than a basement because of the distance from the soil and more ventilation, but "often lower" isn't the same as "fine." Test the space in the finished state to know what you're dealing with.
Question linkAny concrete slab over soil is a potential radon pathway, and a finished, occupied studio is a real exposure scenario. It's a good idea to test the space after it's completed and in closed-house conditions. If levels are elevated, sub-slab depressurization from below the slab is the standard solution.
Question linkThe apartment above grade will likely have lower radon than the walk-out basement below, but it can still have measurable levels, especially if radon from the basement migrates upward through the structure. Test both levels independently. Address any radon in the basement first, which will also benefit the apartment above.
Question linkA permanent foundation means soil contact, and soil contact means radon potential. A tiny home on a permanent slab should be treated the same as any other structure for radon purposes - include RRNC features during construction, or test after occupancy and mitigate if needed.
Question linkYes. Testing during active construction won't give you a meaningful read because the conditions aren't representative of how you'll actually live in the space. Once the project is done and the space is closed up and in occupied conditions for a few days, then test.
Question linkDuring the removal and pour, you're exposing sub-slab soil and temporarily opening a large, direct pathway for soil gas. Radon levels during this period could spike significantly. Ventilate the space well during construction, limit exposure time in the basement during demolition, and test after the new slab is cured and the space is closed up.
Question linkSealing alone almost never achieves meaningful radon reduction on its own. There are too many micro-pathways through concrete and at joints for a sealing-only approach to work reliably. Sealing is a complement to sub-slab depressurization, not a replacement. Be cautious about contractors who make that claim.
Question linkIt can be fine, but make sure the radon mitigation component is being done by someone who is actually licensed in radon mitigation - not just added as a service by a general basement finishing contractor. Radon mitigation has specific requirements and the work should be done by someone who knows the standards and can verify the system is working correctly.
Question linkYes, HVAC changes can affect radon. Changes in how the home is pressurized, where supply and return air is distributed, and how much air is moved through the house can all influence radon dynamics. After a major HVAC replacement, a post-installation radon test is a reasonable precaution to confirm nothing significant has changed.
Question linkAdding central AC doesn't dramatically change the HVAC dynamics the way adding a new system or significantly changing ductwork does, but if the ductwork was modified substantially or you had no central air at all before, testing after the work is done is a good check. It only takes a few days to get a result.
Question linkTighter windows reduce natural air infiltration, which means less natural dilution of indoor radon. After a whole-house window replacement (especially going from old leaky windows to very tight new ones), a radon test is worth doing to confirm levels haven't increased. This is a common scenario where tightening the envelope leads to higher radon.
Question linkTest after the renovation is complete and the home is back to finished, closed conditions. A gutted-to-studs renovation changes too many variables to get a meaningful test mid-project. Once everything is back together and the house is in normal occupied mode, test to establish your post-renovation baseline.
Question linkCheck whether the plumbing penetrations were properly sealed after the repair - gaps around pipes are a common radon entry route. If the floor was patched and sealed well, the increase may be temporary. If levels stay elevated after a few weeks, a mitigation system is the appropriate next step. Give us a call and we can talk through your situation.
Question linkRadon is a long-term lung cancer risk from cumulative radiation exposure - it doesn't cause acute symptoms and there's no way to know from blood tests or symptoms what your personal exposure has been. For concerns about past exposure and what it might mean for you personally, that's a conversation to have with your doctor. What you can do now is mitigate and reduce ongoing exposure going forward.
Question linkRadon doesn't cause headaches or acute symptoms - it's a long-term risk from accumulated radiation exposure over years, not something that causes immediate physical symptoms. Headaches in a newly finished basement are more likely related to VOCs from paint, adhesives, carpet off-gassing, or HVAC air quality. Radon is a separate and serious concern, but it works silently over years - not through acute symptoms you'd notice.
Question linkGet mitigation started as soon as you can. At 5.0, you need to act, and a mitigation system can typically be installed within a week or two of contacting a professional. In the meantime, increase ventilation in that space as much as possible and minimize time down there until the system is in. Then retest after the system has been running for 24 hours to confirm levels came down.
Question linkThis is urgent enough to act on quickly. Move your parents out of the space or minimize their time down there until mitigation is installed. At 8.0, the risk is real and cumulative, and elderly individuals may be more vulnerable. Get a mitigation professional out as fast as you can. This is not a "wait a few months" situation.
Question linkYour neighbor means well, but the premise isn't quite right. Builders are not universally required to address radon - RRNC requirements vary by jurisdiction and are not universal. Even where RRNC features are installed, they don't warranty any specific outcome. The only way to know your home's radon level is to test it.
Question linkThis warrants prompt action. While radon is a long-term risk and a single test result doesn't mean immediate danger, you're right to take it seriously. Get mitigation scheduled as soon as possible. In the meantime, minimize time in the basement. For specific health guidance related to pregnancy, talk to your OB. For the radon system, call us and we'll get someone out quickly.
Question linkThere's no way to calculate individual risk precisely from known radon levels - it depends on many factors including smoking history, individual biology, and exactly how many hours you were in the space. For a personal health assessment, talk to your doctor. What you can control from here is getting mitigation installed now and reducing future exposure. The past is done - don't let the future be the same.
Question linkThat's not consistent with EPA guidance. The EPA recommends action at 4.0 pCi/L and says levels between 2.0 and 4.0 are worth considering mitigation. There's no threshold below which radon is "safe" - it's a dose-dependent risk, and any level of exposure carries some risk. The EPA's 4.0 threshold is a practical action level, not a safety line.
Question linkRadon is the second leading cause of lung cancer in the United States, behind only smoking. It's not about being "worried" in a vague sense - it's about a specific, measurable, addressable environmental risk. Testing and mitigating if needed is the rational response to that information, not anxiety management. Take it seriously.
Question linkIt shouldn't be a surprise - radon tests during real estate transactions are very common. The test will give everyone factual information. If levels are elevated, it's better to know and address it than to have it come up as a surprise. Many sellers choose to mitigate before listing to take the issue off the table entirely.
Question linkEarly in the foundation phase - before the slab is poured. The sub-slab aggregate layer, vapor barrier, and pipe rough-in need to go in before the concrete does. If you wait until the slab is poured, you've missed the easiest window and will be looking at a retrofit installation later.
Question linkYes, firmly. Radon has nothing to do with the age of the house - it's about the geology under the lot. A brand-new custom home on high-radon soil will have elevated radon. The builder's statement reflects a common misconception. RRNC features are inexpensive during construction and much more expensive as a retrofit. Push for them.
Question linkIn most cases in Illinois, yes. Adding RRNC features during construction costs a fraction of what a retrofit mitigation system costs after the fact. If the builder is in a region with any history of elevated radon (which is most of Illinois), the upgrade makes economic sense even setting aside the health considerations.
Question linkIt sounds like they left the vapor barrier material but didn't install it under the slab. That's a problem - the vapor barrier goes in during foundation construction, under the concrete, not after the fact. Ask your builder to clarify what was actually installed under the slab and what the rolled-up sheeting was intended for.
Question linkAn unmitigated elevated radon level can absolutely complicate a sale and affect price negotiations. A properly mitigated home - with a system installed, documented, and retested - is generally not a problem at resale. Most buyers and their agents understand that radon is addressable, and a system in place is a selling point, not a liability.
Question linkIt's fine to box it in or run it through the wall as long as the pipe itself isn't compromised and remains accessible for future maintenance or fan installation. Burying a pipe entirely in a finished wall where you can't get to it later is something to avoid. Make sure you - and future owners - can find and service the system.
Question linkRelocating the pipe is a significant change to your mitigation system and should only be done by a licensed radon mitigation professional, not a general contractor. If the contractor wants to move it for aesthetics, get a radon professional involved to redesign the routing correctly. Moving the pipe incorrectly can reduce effectiveness or compromise the system entirely.
Question linkRunning the pipe through the garage (unheated space) rather than through the conditioned interior reduces the thermal stack effect that helps passive systems work. It can still be activated with a fan and function as an active system, but the passive performance will be weaker. If you test and need to activate the fan, that routing will still work fine - just note it for your records.
Question linkThe new addition gets RRNC features during its construction - it's the right time to do it properly. The existing 1968 structure likely doesn't have any radon rough-in and would need a retrofit if radon is elevated. Test both the existing home and the new addition after construction is done to understand what you're working with.
Question linkYes. The soil and fill material brought in during site prep and grading can have varying radon potential depending on where it came from. Fill from areas with uranium-bearing rock or soil can introduce radon risk even if the surrounding natural geology isn't especially high. This is another reason why testing your specific home is the only reliable way to know.
Question linkRadon doesn't correlate with agricultural land use - it's about the geology, specifically uranium content in the underlying soil and rock. Farmland can have high or low radon depending on what's underneath it geologically. The safest approach is to include RRNC features and test after construction regardless of prior land use.
Question linkICF foundations are concrete walls with foam insulation integrated, and they can actually be somewhat better at limiting radon through the walls because of the additional sealing and insulation. However, radon still enters primarily through the slab-floor connection and sub-slab pathway, so the foundation wall type doesn't eliminate the need for RRNC features and testing.
Question linkYes. The walkout side has above-grade windows, but the rest of the basement is still below grade and still in contact with soil. Radon enters through the slab and below-grade walls, and the walkout openings aren't a reliable enough ventilation source to manage radon on their own. Include RRNC features and test after occupancy.
Question linkBreaking down walls between the garage and living space or basement can create pathways for soil gas from the garage slab to enter the house more directly. It also potentially creates combustion appliance and carbon monoxide concerns. Make sure any connection between the garage and living space is properly sealed afterward, and test radon after the project is done.
Question linkA below-slab shelter is essentially a sub-slab void - and voids under slabs are relevant to radon dynamics. Depending on how the shelter is sealed and ventilated, it could act as a radon collection point. After installation, test radon in the basement to see if there's been any change and consult a radon professional if levels are elevated.
Question linkPier-and-beam or raised foundations with open air below them typically have lower radon levels than slab-on-grade construction because the sub-floor space is open and ventilated. However, if the crawl space under the piers is enclosed or has limited ventilation, radon can still accumulate. Test the living spaces after construction regardless.
Question linkWork with a local radon mitigation professional or follow EPA's Builder's Guide for Radon-Resistant New Construction. The standard package includes gas-permeable aggregate, vapor barrier, interior pipe route, roof penetration, and electrical rough-in for a future fan. It adds modest cost per home and gives your buyers a significant quality-of-life advantage. It's genuinely good building practice in Illinois.
Question linkStone rubble foundations are highly permeable - soil gas can move through them much more freely than through poured concrete. Radon entry through the foundation walls in homes with rubble foundations can be substantial. The mitigation approach typically focuses on sub-slab work but may also involve interior foundation wall treatments. Test and then bring in a professional who has experience with older foundation types.
Question linkIt could be. Any work that opened the slab, created new penetrations, or changed how the basement is conditioned and sealed can affect radon. Check whether new penetrations were properly sealed, and if the system is still elevated several weeks after the project, it's worth a professional assessment to find the new entry point.
Question linkAbsolutely. One year is long enough that a test in normal occupied conditions will give you meaningful results, but short enough that any needed mitigation would be straightforward (especially if RRNC features are already in place). Make it a condition of the purchase or at minimum budget for it as part of your first-week move-in tasks.
Question linkYes, and a renovation like this is a good time to address it. An expanded basement footprint means more sub-slab area to consider, and you'll want to confirm that whatever mitigation system is in place (or gets installed) covers the full new footprint, not just one unit's worth.
Question linkRadon is one of the most significant indoor air quality concerns you can plan for in a green build. It fits naturally into a holistic air quality strategy alongside ventilation (ERV/HRV), VOC-free materials, and filtration. Sub-slab depressurization and RRNC features pair well with a green building philosophy and should be part of the planning from the foundation up.
Question linkYes, bring it up explicitly. Architects and designers don't always incorporate RRNC features by default - sometimes it falls to the owner to request it. Ask them to include proper RRNC specification in the foundation and rough-in plans. If they're unfamiliar with it, the EPA Builder's Guide is a good reference.
Question linkAny habitable room on a concrete slab over soil has radon exposure potential. A sunroom addition that's used regularly - especially one tempered well enough to be occupied through much of the year - warrants radon consideration. Test the addition after it's complete and occupied, and if levels are elevated, a small sub-slab system for that footprint is very doable.
Question linkGeothermal drilling is typically for loop fields away from the house footprint, and the closed-loop system doesn't directly connect soil gas to indoor air. It's unlikely to affect radon in the house. Even so, if the drilling happens near the foundation and disrupts the soil there, a post-installation test is a reasonable precaution.
Question linkThe heating system itself doesn't change the radon dynamics from the soil below, though the installation process (breaking and re-pouring concrete) temporarily opens the slab. Make sure the new concrete pour is properly installed and consider testing the garage and adjacent interior spaces after the project is complete.
Question linkBoth are potential sources. Crawl spaces can sometimes be higher because the soil is more directly exposed to the air in that space. The basement's concrete slab provides more of a barrier but isn't impermeable. The whole-home picture matters - test both zones and address what you find. A mitigation system that covers both footprints is doable in this kind of mixed-foundation situation.
Question linkA thin leveling compound pour over existing slab doesn't meaningfully change radon dynamics. It's thin, bonded to the existing concrete, and not a radon barrier. Your radon situation after this project will be essentially the same as before it. If you had radon concerns before, address them through sub-slab depressurization, not the floor system.
Question linkA continuous radon monitor is a great long-term investment for a new home, especially one with an active RRNC system where you want to verify it's working. Devices from brands like Airthings and Safety Siren are well-regarded for home use. They give you ongoing awareness rather than a single point-in-time test. Just make sure you're testing in the lowest occupiable level to get the most meaningful reading.
Question linkIt means the builder installed the full active system - fan, pipe, electrical - rather than just the passive rough-in. Pre-activated is a good thing. You still want to test to confirm it's performing well and actually reducing radon to acceptable levels, but you're starting from a better place than a passive-only system.
Question linkDon't turn it off. Radon entry is influenced by the temperature differential between indoors and outdoors, and winter conditions in Illinois actually tend to drive higher radon levels because the pressure gradient is strongest when it's cold outside. Turning off the fan in winter is exactly the wrong time to do it. The energy draw is small - comparable to a night light. Keep it running year-round.
Question linkIf you haven't tested yet, yes - test before the ceiling goes up if you want to preserve easier access to the joist bays for any future work. At minimum, know your radon situation before you seal up the ceiling. If your radon is elevated and needs mitigation, the pipe routing may need to go through or around the ceiling area, and that's easier to plan before the drywall is up.
Question linkA builder's subjective experience over 30 years doesn't substitute for a test on your specific home. They may be telling the truth - or they may simply not have had systematic feedback from every homeowner about radon levels. Either way, the test is cheap, quick, and tells you what's actually happening in your home. Trust the data.
Question linkUnderpinning is significant foundation work that disturbs the soil around and below your existing foundation. Any major sub-foundation work like this warrants a pre-project radon test to establish baseline and a post-project test to confirm conditions haven't changed significantly. If changes are found, work with a radon professional to address them.
Question linkAsk for the post-mitigation test results - a properly installed system should come with documentation showing the radon level after installation. You can also look for the visual indicators: the pipe, the fan, the manometer gauge showing negative pressure. But honestly, running your own independent test after you move in is the only way to confirm what's actually happening now.
Question linkStructural changes that alter air flow paths in the house could theoretically affect radon dynamics, but moving an interior load-bearing wall is unlikely to have a significant direct effect on radon. The main concern would be if any foundation or slab work is involved. Post-renovation testing is always a reasonable step after a significant remodel.
Question linkA test credit is only useful if you're committed to following through with the test and the mitigation if needed. Make sure the credit is enough to cover both a proper test and the mitigation system if it comes back elevated - not just the test itself. Better still, if radon is a concern, ask for the RRNC features to be installed rather than a cash credit that may not be enough to cover a full retrofit.
Question linkPossibly the opposite of what you'd expect, right? If the floor drain trap was allowing radon to come in, sealing it should help. But if the drain was also serving as a minor pressure-relief vent for sub-slab pressure, sealing it might have redirected that pressure through other pathways. At elevated levels, you need sub-slab depressurization, not more sealing experiments.
Question linkAsk whether they're licensed by NRPP or NRSB, how long they've been working in radon mitigation, what their post-installation retest protocol looks like, and whether they'll provide a written warranty to fix the system if levels aren't adequately reduced. Ask for references from similar projects and make sure you understand exactly what they're installing before they start.
Question linkReplace the fan promptly and retest after it's been running for at least 24 hours before doing the follow-up test. At 7.2, you want to confirm the system is back to where it should be. This is also a good reminder to check your manometer gauge periodically so you catch fan failures quickly rather than months later.
Question linkRadon rarely comes up in community-level marketing - it's a home-by-home assessment. The silence on radon from the community doesn't mean it's not present. Test your specific lot and home. If RRNC features aren't standard in the community, ask whether the builder will add them, or plan to test and potentially mitigate after you move in.
Question linkYou can run a DIY test with a mail-in charcoal canister kit, which gives you a solid baseline reading. For a new home with RRNC features you want verified, or for a legal real estate transaction, a professionally conducted test by a licensed tester carries more weight and may be required. For general personal knowledge, a quality DIY test is a reasonable starting point.
Question linkA concrete floor over soil in a converted barn is exactly the same situation as any slab-on-grade residential structure from a radon standpoint. Test after the conversion is complete and in occupied conditions. If levels are elevated, a sub-slab depressurization system is the standard solution. The residential conversion changes the radon significance because now people are living and sleeping there.
Question linkGood sealing around penetrations is a positive step and does reduce one entry pathway, but it's not a comprehensive radon solution. Sub-slab pressure and the floor-wall joint and many micro-pathways through concrete aren't addressed by pipe-penetration sealing alone. It's a complement to mitigation, not a replacement.
Question linkYes, it's worth paying attention to. Illinois has significant radon risk, particularly in the northern and central parts of the state. A builder unfamiliar with local conditions may not proactively include RRNC features. Ask explicitly whether they're including radon-resistant features, and if not, insist on it or get it in writing as a specification before construction begins.
Question linkBasement residential units in an old masonry building are a higher-risk scenario - masonry foundations are porous, and the connection to soil can be more direct than through a poured concrete slab. Each basement unit is a potential radon concern. Testing each unit independently and installing mitigation systems appropriate to the building type is the right approach. This is also worth getting on the developer's radar early since it affects unit design.
Question linkBuilder warranties on RRNC systems usually cover the materials and workmanship of the installed components - the pipe, connections, and vapor barrier - not a specific radon outcome level. Read the warranty carefully to understand what's actually covered. A warranty that the pipe was installed correctly is different from a warranty that radon will be below 4.0 pCi/L.
Question linkThat's overstated. A passive RRNC system is a rough-in that reduces the likelihood of elevated radon and makes activation easier - it doesn't eliminate radon or handle it automatically. Whether it actually keeps your home's radon at acceptable levels is something a test tells you, not a sales agent. Test after move-in and find out for yourself.
Question linkOne test gives you a starting point and is worth doing. For a more complete picture, a long-term alpha-track test run over 90+ days is more reliable than a single 48-hour reading. If the builder's one-time test comes back fine, consider doing a long-term follow-up test in your first or second year to confirm the result holds across seasons.
Question linkNot necessarily, but it's worth asking whether the subcontractor is licensed in radon mitigation or familiar with RRNC installation standards. An RRNC system installed by someone without that background can have subtle problems - wrong pipe diameter, poorly sealed joints, pipe terminates in the wrong location - that only show up when you test.
Question linkIt's not universally standard, but it's also not unusual for buyers to request it. Many buyers and real estate agents request a post-completion radon test as part of the home inspection process. You can make it a condition of your purchase or request it through your buyer's agent. It's a reasonable ask.
Question linkYes, this is a negotiable item in many new construction purchases, especially if you're buying before or during the build phase. Put it in writing as a specification. A builder who pushes back hard on this is worth questioning - RRNC activation during construction is a modest additional cost and a clear benefit to the buyer.
Question linkExiting through an exterior wall is permissible, but the termination point matters - it needs to be above windows and doors, away from any air intakes, and positioned so exhausted gas can't re-enter the house. Roof penetration is generally cleaner and more reliably positioned. If your pipe exits through the garage wall, ask your builder to confirm the termination location meets EPA guidelines.
Question linkAsk them to add it before closing if at all possible. Running an electrical line to the attic or wherever the fan would mount is much easier during construction than after walls and ceilings are finished. If they won't, know that a radon professional can still wire a fan later - it's just more work than if the outlet were already there.
Question linkNot at all. Six months in is a perfectly reasonable time to test - you're in the home under real living conditions, the HVAC has run through at least part of the seasonal cycle, and the result will give you a meaningful baseline. Test now and go from there.
Question linkBoth are real - that's seasonal variation doing its thing. Winter readings are typically higher because closed-house conditions, indoor-outdoor pressure differences, and reduced natural ventilation all favor radon accumulation. The winter reading is usually more conservative and more meaningful for understanding your worst-case exposure. Consider a long-term alpha-track test to get the annual average.
Question linkYes, radon levels naturally fluctuate throughout the day based on pressure changes, temperature, wind, HVAC cycling, and other factors. Continuous monitors show this real-time variation, which can be alarming if you expect a steady number. Look at the weekly or monthly average, not the hourly peaks and valleys, for a meaningful assessment.
Question linkPractically, the most useful placement is the lowest occupiable level - that's where radon concentrations are typically highest and where most people spend meaningful time. A continuous monitor in the basement or main floor gives you the most actionable data. Upper floors in most homes with good mitigation will be lower, and additional monitors there add cost without proportional information value.
Question linkNot precisely, unless a test was done before activation. You can make an educated inference from your post-mitigation level - if you're at 1.2 pCi/L after the system is running, your pre-mitigation level was likely higher, but how much higher depends on how effective the system is and the local geology. If you're ever curious, you can temporarily turn off the system (not recommended long-term) and run a short test, but that's only useful for comparison purposes.
Question linkAll three are real data points - radon testing has some inherent variability, and repeated tests rarely land on exactly the same number. Look at the range: if all three are comfortably below 2.0 pCi/L, you're in good shape. If they cluster around 4.0 or above, that's a consistent signal to act on. A long-term test is the most reliable single reading because it averages out the variation.
Question linkRun a radon test in the first month or two to confirm the system is performing well. Then check the manometer gauge periodically (monthly or seasonally) to make sure the system is maintaining negative pressure. After one year, run another test to confirm the system's continued performance. Keep records of all tests.
Question linkA short-term test under proper closed-house conditions is a reasonable basis for making that decision, especially if the result is clearly above or below 4.0 pCi/L. If you land right around 3.5-4.5 and want to be confident before spending money, following up with a long-term test to confirm the average gives you better data. For a clear result well above 4.0, don't wait for a long-term test - act on the short-term result.
Question linkHome inspector radon tests can vary in quality. Make sure the inspector used a properly calibrated device and followed closed-house protocol (windows and doors closed for at least 12 hours before and during the test). If the inspector used a continuous electronic monitor that they carried to multiple inspections that day, ask about calibration. A licensed tester with proper equipment is the gold standard.
Question linkAt below 1.0, your system is performing very well. Keep the fan running and check the manometer periodically. Retest every two years or after any significant renovation. There's no action needed at that level - just maintain what you have.
Question linkRemoving a drop ceiling doesn't directly affect radon - the tiles and grid are above the basement level, not a radon barrier. But if the work disturbs the HVAC system, the sump area, or the sub-slab, those changes could have indirect effects. Test after a major renovation to establish a new baseline.
Question linkOnce the addition's basement is connected to your existing basement, they're essentially one space from an air dynamics standpoint. If your existing basement has mitigation, it may or may not adequately cover the new addition footprint depending on how it's designed. After the connection is made and the addition is complete, test and bring in a radon professional if levels have changed.
Question linkSplit-levels with a half-below-grade lower level are very common radon scenarios. The below-grade walls and floor are in soil contact, and that level is typically a family room or bedroom space people spend significant time in. Test the lower level specifically, and if it's elevated, a radon professional can design a system for the partial-below-grade configuration.
Question link3.1 before renovation in a space that's about to become a full-time occupied apartment warrants serious consideration of mitigation. The EPA's 2.0-4.0 range is described as worth considering - for elderly daily occupants, that consideration should lean toward acting on it. Factor mitigation into the renovation budget.
Question linkA bathroom above the garage is on the second floor, which is significantly removed from the soil. Radon at that height is typically much lower than at slab level. Even so, if the garage below has high radon and the floor between garage and bathroom isn't well sealed, there's a pathway. Ventilate the garage space and test the bathroom after construction to be sure.
Question linkFloating floors over concrete (vinyl plank, laminate) and tile don't meaningfully change radon dynamics. If you're removing old carpet and leveling the slab, any slab work is worth noting. Generally, flooring replacements don't create radon issues, but testing after any major basement renovation is a good habit.
Question linkVery likely yes. An unfinished basement full of storage has the same radon dynamics as an empty one. Cleaning out storage doesn't change the sub-slab situation. The 6.4 reading reflects your home's actual radon situation, which the previous owners probably never tested. At 6.4, get mitigation on the schedule promptly.
Question linkIf you or guests spend time in the wine cellar, yes - but most wine cellars have limited human occupancy (brief visits to retrieve bottles), which keeps cumulative exposure low. Where it matters more is if the wine cellar is sealed tightly and connected to the rest of the basement - radon that builds up in the cellar could spill into adjacent occupied spaces. Test the cellar and adjacent basement areas together.
Question linkHigh humidity itself doesn't cause higher radon, but the hot tub room may have changed the pressure and ventilation dynamics in the basement. If exhaust fans are running to manage humidity, they can depressurize the space and draw more soil gas in. Review the ventilation setup and consider whether the exhaust fans are creating conditions that amplify radon entry.
Question linkCheck whether the system is still operational - confirm the fan is running, the manometer shows negative pressure, and do a current radon test. If it tests fine and the equipment is functioning, it may not need updating. If the fan sounds worn, the gauge shows no pressure, or radon levels are elevated, evaluate whether the existing system needs repair, upgrading, or replacement.
Question linkYes. The mitigation system's pipe routing and slab entry point need to be protected during the renovation. Make sure your contractor knows where the pipe enters the slab and doesn't damage or block it. After the renovation is complete, test to confirm the system is still performing correctly.
Question linkA reinforced safe room built within the existing basement doesn't fundamentally change the sub-slab dynamics. If the safe room adds a new slab penetration for anchor bolts or involves any sub-slab work, those areas should be properly sealed. Test after construction to confirm no change.
Question linkMore natural ventilation pathways can help slightly with dilution, but they're not a mitigation system. The radon entry is from below the slab, and opening the walk-out level more doesn't address that source. If radon was elevated before the conversion, it will likely still be elevated after - test after the project is done.
Question linkEarth-sheltered homes have extensive soil contact on their walls and often roof, which means more surface area for potential radon entry than a conventional home. They often also rely on passive solar and have less natural ventilation. Radon is a very real concern in earth-sheltered construction and should be addressed with active sub-slab or sub-membrane depressurization as a standard part of the design.
Question linkIf the greenhouse is attached to the house and shares air with it, radon from the greenhouse floor can contribute to household levels. If it's a separate, non-conditioned space you're not spending extended time in, it's less of a concern. Test the attached greenhouse and the adjacent interior rooms if you spend significant time in or near that space.
Question linkAdding a second story doesn't directly affect the sub-slab radon dynamics. However, if the project involves significant foundation work, changes to the HVAC system, or modifications to how air moves through the house, a post-project radon test in the basement and lowest level is a reasonable check. Major changes to building envelope or mechanical systems warrant a retest.
Question linkAttic bedrooms are the farthest point from the soil and typically have the lowest radon levels in a home. Radon concentrates in the lowest levels and generally decreases with height. While no space is completely immune, an attic bedroom is the least-likely radon trouble spot in a house. If you're concerned, test it, but focus your radon energy on the basement and first floor.
Question linkThe radiant tubing in the slab doesn't prevent sub-slab depressurization from working, but it does require that any drilling through the slab for the radon pipe is done carefully to avoid hitting the tubing. A radon professional familiar with these situations can work around the tubing with proper planning. It adds a layer of complexity but isn't a deal-breaker.
Question linkThe radon risk is from the soil and geology of that lot, which doesn't change when you tear down and rebuild. The same soil under the same location will have similar radon potential for the new structure. Include RRNC features in the new construction and test after occupancy - the rebuild doesn't reset the geology.
Question linkThe underlying geology is what drives radon, and a former parking lot just means there was previously asphalt over the same soil. The radon potential of the lot is about the subsoil and bedrock beneath it, not what was on the surface before. Include RRNC features and test after construction as you would for any new build.
Question linkWaterproofing and radon mitigation are related but not identical. Some waterproofing measures (vapor barriers, sealed penetrations) can reduce radon entry modestly. But a waterproofing company claiming to seal out radon should specify exactly what they're doing that constitutes actual radon mitigation. Sub-slab depressurization is the proven solution - sealing alone is not.
Question linkRadon in a townhome depends primarily on the connection to soil - if your unit is on a slab or has a basement with slab, radon dynamics are similar to a single-family home. Shared walls with neighboring units don't typically affect your radon levels significantly. Test your unit independently and address your own mitigation if needed.
Question linkA highly sealed, low-ventilation enclosure in the basement could accumulate radon more than an open basement space. If you or guests will enter the wine room regularly, test it specifically and consider whether it needs its own ventilation or is covered by the main mitigation system. A tight room in the basement with no airflow is a scenario worth checking.
Question linkWaterborne radon is a real phenomenon - radon dissolved in well water can be released into the air when water is used (showering, washing dishes). It's generally a smaller contributor to indoor air radon than soil entry, but it can be meaningful in some homes. Test both indoor air and water if you're on a private well and want the full picture.
Question linkHelical pier installation involves drilling through or alongside the foundation, which can disturb the sub-slab area. After any significant foundation repair work, a radon test is a reasonable step to confirm the repair didn't create new entry pathways or change existing conditions.
Question linkIdeally, the radon system gets installed at the point where the slab and walls are still accessible but before the final flooring, drywall, and ceiling work is done. The sub-slab suction point needs slab access, and the pipe routing is easier before walls are closed. Coordinate with your renovation contractor to schedule the radon professional at the right stage.
Question linkA net-zero home is typically very tight, which makes radon management even more critical. Include active sub-slab depressurization from the start rather than relying on a passive system, and pair it with an ERV for balanced ventilation. Net-zero and good radon mitigation are completely compatible - plan for both in the mechanical design phase, not as afterthoughts.
Question linkUnless you were on-site during the foundation pour to observe it, you can't verify it visually after the fact. Asking for photos from the construction process is reasonable. You can also ask for the builder's specification sheet or subcontractor documentation confirming the layer was installed. If you have serious doubt and the foundation is accessible, a radon professional can sometimes assess sub-slab communication through a diagnostic test - good communication suggests the aggregate is there.
Question linkThe cost to add RRNC features during construction is modest. The cost to retrofit a full mitigation system after the fact - with finished walls, finished basement, and no rough-in in place - is meaningfully higher and involves more disruption. Beyond the financial comparison, you'd be starting your time in the home without knowing your radon situation. The savings from skipping RRNC are unlikely to be worth it.
Question linkA second-floor space above a garage is somewhat removed from the soil-level radon source, but if the garage itself has elevated radon and the floor between the garage and the suite above isn't well sealed, there's a pathway. Ventilate the garage appropriately and test the suite after construction. If radon is found in the suite, the garage slab is the likely source to address.
Question linkSome radon fans in certain configurations can produce condensation in humid conditions, and the pipe may have a condensation drain built in. This is normal in some climates and installations. Make sure the drain doesn't back up and that water is properly routed - a blocked drain can affect system performance in some configurations. Ask your installer where the drain goes and whether any periodic check is needed.
Question linkIf you have site access during construction, the sub-slab phase is the critical one to observe - look for the gravel or aggregate layer, the vapor barrier being laid over it, and the pipe going in before the slab pour. Take photos. After the slab is poured, verify the pipe is where it should be and ends up properly routed to the attic and through the roof. These are the hardest things to verify after the fact.
Question link"Up to code" means the installed components met whatever local or state requirements were in effect - but codes are minimum standards, not optimal outcomes. It doesn't mean radon levels in your home are below any threshold. It means the rough-in was installed according to the rules. Your test result, not the code compliance, tells you whether you need further action.
Question linkA properly designed and functioning system should bring most homes well below 4.0 pCi/L. If a retest after activation is still high, the next steps include: verifying the fan is running and maintaining pressure, checking for bypassed entry points (open sump crock, drain tile channel, floor-wall joint gaps), and potentially adding a second suction point if the sub-slab communication is poor. A professional should diagnose and fix it - most systems come with some form of performance commitment.
Question linkRun a radon test - ideally a long-term alpha-track test in the lowest level of the home, started in the first few weeks after move-in. Getting a 90-day reading gives you a solid baseline that captures some seasonal variation and is much more reliable than a single 48-hour result. If it comes back elevated, you'll know early and can address it before you've spent years in the space. That's the most impactful thing you can do.
Question linkQuestions are fine too. Call or text Bill, or send your address and contact info, and he will take it from there.
Reviewed by Bill Dahlstrom, Illinois radon mitigation license RNM2018212.