DIY radon mitigation: how to lower radon in your home, step by step
TL;DR: DIY radon mitigation starts with confirming your long-term average (ideally 90 days or more). If it is 4.0 pCi/L (148 Bq/m³) or higher, the EPA recommends fixing your home. Start with low-cost DIY steps: seal foundation cracks and pipe gaps, cover your sump pit, lay a vapor barrier over exposed earth, and improve ventilation. Sealing alone is rarely enough, so if levels stay high you need an active sub-slab depressurization (ASD) radon mitigation system: PVC pipe through the slab, a radon fan, and a vent above the roof. Experienced DIYers can install one for a few hundred dollars in parts, but most homeowners hire a certified pro, typically for $800–$2,500. Retest no sooner than 24 hours after the fan starts, then keep monitoring to confirm the fix keeps working.
Have you recently tested your home and found high radon levels? It’s normal to feel daunted. Radon is a radioactive gas, and long-term exposure to high levels is the leading cause of lung cancer among non-smokers in the United States. The good news: high radon is fixable. Health Canada says a sub-slab depressurization system reduces radon by more than 80% in most homes.
New to radon? Start with our guide: What is radon? Understanding the invisible gas and safe indoor levels. Want to know how common radon is where you live? Check the Airthings radon map.
As the EPA (Environmental Protection Agency) states:
Radon reduction systems work. Some radon reduction systems can reduce radon levels in your home by up to 99 percent. Most homes can be fixed for about the same cost as other common home repairs.
Can you do radon mitigation yourself?
Yes, partly. Several DIY steps help lower radon, and a homeowner with significant home-repair experience can install a basic sub-slab radon mitigation system. But if your long-term average remains at 4.0 pCi/L (148 Bq/m³) or higher after simple fixes, you will most likely need an active sub-slab depressurization (ASD) system. The EPA and state radon programs recommend having it installed by a certified or licensed radon mitigation professional, because a poorly installed system can fail to lower radon, or cause furnace or water-heater exhaust to backdraft into the home.
What radon level needs mitigation?
| Long-term average | What to do (US EPA) |
|---|---|
| Below 2.0 pCi/L (74 Bq/m³) | No action needed; keep monitoring |
| 2.0–3.9 pCi/L (74–147 Bq/m³) | Consider fixing (EPA) |
| 4.0 pCi/L (148 Bq/m³) or higher | Fix your home (EPA action level); an active mitigation system is usually needed |
Outside the US, action levels differ: Health Canada recommends action above 200 Bq/m³ (5.4 pCi/L), and the WHO recommends a reference level of 100 Bq/m³ (2.7 pCi/L), and no higher than 300 Bq/m³ where that isn’t achievable.
DIY radon mitigation step by step
- Confirm your long-term radon level with a continuous monitor.
- Seal radon entry points: foundation cracks, pipe gaps, sump pit, crawlspace earth.
- Improve ventilation as a temporary stopgap.
- Install an active radon mitigation system (sub-slab depressurization with a radon fan) if levels stay high.
- Retest no sooner than 24 hours, and within 30 days, after installation.
- Keep monitoring to make sure the system keeps working.
Step 1: Confirm your home’s average radon level with continuous monitoring
Before you spend weekends caulking your basement or hundreds of dollars on supplies, make sure you actually have a long-term radon problem.
Short-term, mail-in charcoal tests likely won’t give you an accurate picture. Radon levels fluctuate constantly, especially when the weather changes (such as snowfall or heavy rainfall). A high reading from a 48-hour test does not necessarily mean your home’s year-round average is dangerous.
Read our guide on radon testing to learn more: How to test for radon.
The DIY fix: Don’t guess. Install a continuous digital radon monitor in the lowest lived-in level of your home, preferably during the colder months. A few weeks of data gives a strong indication, and 90 days or more gives a reliable long-term average. If that average is at or above 4.0 pCi/L, move on to the mitigation steps below. A continuous monitor also shows you, in real time, whether each fix is working. Not sure which monitor to choose? See How to choose a radon detector.
Measure before, during, and after you mitigate
One monitor confirms you have a problem, shows whether each DIY fix is working, and tells you if a mitigation system ever stops doing its job. No lab, no repeat test kits.
Corentium Home 2
Battery-powered radon monitor for basements, with daily, weekly, and long-term averages in the app, plus temperature and humidity.
View Radon
Smart radon monitor for the basement or ground floor, with remote access to your readings.
Living Room + Basement
View Radon for the basement plus View Plus for complete air quality in your main living space.
Step 2: Seal radon entry points in your foundation
Radon is pulled up from the soil into your home because the air pressure inside your house is lower than the pressure in the ground. Sealing the gaps in your foundation reduces how much gas gets in, and makes any mitigation system you add later work better.
The EPA does not recommend sealing alone to reduce radon: it rarely lowers levels enough on its own. But it is a low-cost DIY starting point, and it makes an active system more effective.
- Caulk foundation cracks: Inspect your basement floor and walls. Clean out visible cracks and fill them with a high-quality elastomeric polyurethane caulk (not standard silicone, which peels away from concrete over time).
- Seal pipe penetrations: Check where plumbing pipes, wiring, or gas lines pass through the concrete floor or walls. Seal these gaps tightly with expanding foam or polyurethane caulk.
- Cover your sump pump: An open sump pit is effectively an open chimney for radon. Install an airtight, gas-tight sump cover and seal pipe penetrations through the lid with rubber grommets.
- Treat exposed earth: If your crawlspace has a dirt floor, lay a high-density polyethylene vapor barrier (at least 6-mil thick). Overlap the seams and tape them securely to the foundation walls.
Step 3: Improve home ventilation
Radon builds up when a house is sealed tight. Bringing in more outdoor air dilutes radon indoors.
- The DIY fix: Open basement windows on opposite sides to create a cross-breeze, or run a window fan blowing fresh air into the basement. Avoid fans that exhaust air out of the basement: lower indoor air pressure (from exhaust fans, dryers, or furnace venting) draws more radon in from the soil.
- The catch: The EPA calls natural ventilation a temporary approach: radon usually returns to previous levels within about 12 hours of closing windows. It isn’t practical in cold winters or hot summers. Use it as a stopgap while you plan a permanent fix.
After each DIY step, check your radon monitor over the following days and weeks to see how much difference it has made.
Step 4: Install an active radon mitigation system (sub-slab depressurization)
If you’ve sealed entry points and improved ventilation but your long-term average is still at or above 4.0 pCi/L, DIY sealing has reached its limit. The next step is an active sub-slab depressurization (ASD) system, regarded as the “gold standard” for reducing radon in homes with a basement or slab foundation.
How does a radon mitigation system work?
An ASD system uses a continuously running radon fan to create low pressure beneath your foundation. This draws radon from the soil into a pipe and vents it safely above the roof before it can enter the house, reversing the natural pressure difference that pulls radon indoors. It is the primary technique described in the EPA’s Consumer’s guide to radon reduction: how to fix your home. Homes with a crawlspace usually use a variation called sub-membrane depressurization, where the suction pipe draws air from under a sealed vapor barrier.
Parts of a radon mitigation system
- Suction point: a hole cored through the slab, with a small pit dug out beneath it to improve airflow.
- PVC vent pipe: usually 3- or 4-inch Schedule 40 PVC, running from the suction point to the outside.
- Radon fan: a sealed in-line fan rated for radon, typically $100–$300. The EPA says it must not be in or below a living area and should be in unconditioned space, such as the attic or the outside of the house.
- Manometer (U-tube gauge): a simple pressure gauge (about $10–$20) on the pipe that shows the fan is pulling suction. Check it regularly.
- Exhaust: per the EPA, the pipe must vent above the roof surface, at least 10 feet above the ground, and at least 10 feet from windows, doors, or other openings unless it is at least 2 feet above them.
- Sealing and labels: sealed cracks and pipe joints, and a label identifying the system.
How to install a DIY radon mitigation system
If you decide to install an ASD system yourself, get guidance from your state radon office first, and follow the national installation standard for existing homes (ANSI/AARST SGM-SF-2023). Many states require radon mitigators to be licensed, certified, or registered, so check local rules before you start. In outline, the process is:
- Pick the suction point: usually near the center of the slab, close to where the pipe can run up and out of the house (often near an exterior wall or utility area).
- Test sub-slab airflow: drill a small test hole and check that suction reaches across the foundation. Poor airflow (dense soil or several footings) may need more than one suction point.
- Core the slab and dig the pit: core a 4–6 inch hole for the pipe and remove some fill material beneath it to create a suction pit.
- Run the PVC pipe: run the pipe from the pit to the outside, either up through the house (via the attic) or out through the rim joist and up the exterior wall, with as few bends as possible. Seal around the pipe where it passes through the slab.
- Mount the radon fan in unconditioned space: in the attic or on the outside of the house, never in or below a living area, because a leak on the fan’s pressurized side could push radon indoors. Use rubber couplings to connect it.
- Vent above the roof: at least 10 feet above the ground and 10 feet from windows, doors, and other openings (or 2 feet above them).
- Install the manometer, seal, and label: fit the U-tube gauge, seal remaining cracks and joints, and label the system.
- Wire the fan and turn it on: use a grounded, weather-appropriate electrical connection; hire an electrician if needed.
- Check for backdrafting: make sure the furnace, water heater, and other combustion appliances still vent properly with the fan running.
Choosing and placing a radon fan
Radon fans are sealed, in-line fans built to run 24/7. The right size depends on how easily air moves under your slab, which is why professionals run pressure tests first. Residential models range from under 20 watts to well over 100 watts. As a rule of thumb from the Minnesota Department of Health, a fan’s wattage roughly equals its yearly running cost in dollars at 10¢ per kWh; at 15¢ per kWh, a 60-watt fan costs about $80 a year. Expect the fan to last around 5 to 10 years. A falling manometer reading or rising radon levels are the signs it needs attention.
Why most homeowners hire a professional
- Sizing an ASD system needs diagnostic pressure testing to make sure the fan can pull air from under your entire foundation.
- A badly installed system can fail to lower radon, or cause combustion appliances to backdraft, bringing carbon monoxide into the home.
- Many certified contractors guarantee their work and design the system to bring levels below the EPA action level.
What about HRVs (heat recovery ventilators)?
An HRV, also called an air-to-air heat exchanger, adds permanent ventilation by bringing in outdoor air and using the outgoing air to warm or cool it. This helps lower radon, especially when the HRV ventilates only the basement. For whole-home radon reduction, an ASD system is generally recommended.
Where to find a certified radon professional
The EPA recommends using a certified or qualified professional. In the US, use the NRPP (National Radon Proficiency Program) search. In Canada, use C-NRPP (Canadian National Radon Proficiency Program).
Step 5: Retest after installation
A professional usually installs a system in less than a day. The fan starts working immediately, and a continuous monitor will often show levels falling within the first day or two. The EPA recommends a post-mitigation test no sooner than 24 hours after the system starts and within 30 days of installation, then retesting at least every two years. A well-working system typically brings levels below 2 pCi/L.
Radon mitigation cost: DIY vs professional
| Fix | Typical cost (US) | Impact on radon |
|---|---|---|
| Sealing cracks and pipe gaps (caulk, foam) | Low; a few tubes of polyurethane caulk and foam. Sealing a whole unfinished basement with radon sealant: $400–$1,000 | Limited on its own; helps an active system work better |
| Radon fan | $100–$300 (fan kits with couplers and a gauge from about $170) | The core of an active system |
| DIY sub-slab system (fan, PVC pipe, fittings, manometer, sealant, core-drill rental) | Roughly $300–$600 (our estimate from current part prices) | High, if designed, sized, and installed correctly |
| Professional sub-slab depressurization system | $800–$2,500; most homes about $1,000–$2,000 | High; up to 99% reduction, often guaranteed |
| Running cost (fan electricity) | About $20–$150 a year, depending on fan size and power prices | Ongoing |
Costs vary with your home’s size, foundation type, and layout; larger or more complex homes can cost up to about $3,000. The EPA says most homes can be fixed for about the same cost as other common home repairs, and recommends getting estimates from one or more qualified contractors. For a full breakdown, see Radon mitigation cost: DIY vs. professional.
Step 6: Keep monitoring after mitigation
Radon mitigation isn’t “set it and forget it.” Houses settle, new cracks form, and radon fans eventually wear out (typically after 5 to 10 years). Keep monitoring continuously after mitigation. A digital monitor connected to an app, like the Airthings Corentium Home 2, shows you if radon levels change or start to creep back up.
Know your system is still working. A continuous radon monitor shows if levels start creeping back up after mitigation, long before a yearly test would.
Case study: a DIY radon mitigation that worked
For Judith Spence, radon wasn’t top of mind when she moved from the city to the Canadian countryside for a healthier life. After learning about uranium mining in the region and testing her home with an Airthings monitor, she found radon levels around 100 times higher than the average outdoor level. Judith’s husband installed a radon mitigation system and sealed cracks around the foundation. Their Airthings monitor showed radon levels dropping almost immediately after the system was switched on, giving them peace of mind that their home was safe.
Frequently asked questions
Can I mitigate radon myself?
Partly. Most homeowners can seal cracks and pipe gaps, cover a sump pit, lay a crawlspace vapor barrier, and improve ventilation themselves. Installing an active sub-slab depressurization system is possible if you have significant home-repair experience, but it requires pressure testing and knowledge of airflow and building design, so a certified professional is recommended. Many states require radon mitigators to be licensed, certified, or registered.
What is a radon mitigation system?
A radon mitigation system is a permanent setup that keeps radon out of your home. The most common type, active sub-slab depressurization, uses a radon fan and PVC pipe to pull radon from beneath the foundation and vent it above the roofline.
What is the cheapest way to lower radon?
Start with low-cost DIY steps: seal foundation cracks and pipe penetrations, cover an open sump pit, and lay a vapor barrier over exposed earth in a crawlspace. Ventilation is free but temporary. These steps help, but the EPA does not recommend sealing alone as a fix. Use a radon monitor to see how much each step helps before deciding whether you need an active system.
Where should a radon fan be installed?
In unconditioned space outside the living area, usually the attic or the outside of the house. The EPA says the fan must not be located in or below a livable area, because a leak on its pressurized side could push radon into the house.
How long does a radon fan last?
Typically 5 to 10 years of continuous use. Check the manometer on the pipe regularly and watch your radon monitor; a drop in suction or rising radon levels are signs the fan needs replacing.
Does opening windows reduce radon?
Yes, temporarily. Fresh air dilutes radon, but the EPA notes that levels usually return to previous values within about 12 hours of closing windows and doors.
How long does DIY radon mitigation take?
Sealing cracks and improving ventilation can often be done in a weekend. A professional usually installs a sub-slab system in less than a day; a first-time DIYer should plan for a full day or more, depending on the home.
Will sealing foundation cracks stop radon?
Not on its own. The EPA does not recommend sealing alone to reduce radon. It closes some entry points and works best combined with an active mitigation system.
How much is professional radon mitigation?
In the US, a professionally installed sub-slab depressurization system typically costs $800–$2,500, with most homes around $1,000–$2,000. Larger or more complex homes can cost up to about $3,000. The fan then adds roughly $20–$150 a year in electricity.
How do I know if my radon mitigation worked?
Measure again. The EPA recommends testing no sooner than 24 hours after the system starts and within 30 days of installation. A continuous radon monitor shows how levels change after each fix and builds a new long-term average; a test kit can also confirm the result once its test period is over.
Can an air purifier remove radon?
No. Radon is a gas, not a particle, so HEPA filters and air purifiers cannot trap it. The only way to remove radon is to keep it out or vent it outside.
Do I need to mitigate if my level is 3.0 pCi/L?
The EPA recommends that you consider fixing your home if your long-term level is between 2.0 and 4.0 pCi/L. It is below the action level, but reducing exposure to a known carcinogen is always the safer choice.
Can radon come back after mitigation?
Yes. Weather, seasons, foundation shifts, a failing fan, or changes to ventilation can all raise levels again. The EPA recommends retesting at least every two years; a continuous monitor makes this automatic.
Should I test again after renovations?
Yes. Renovations that affect your foundation, insulation, ventilation, or airflow can change how radon enters your home. Retest after major work, especially in basements or lower levels.
Sources
- US EPA (Consumer’s guide to radon reduction: how to fix your home)
- US EPA (How much can a radon mitigation system cost?)
- US EPA (Radon zones and state radon information)
- Health Canada (Reducing radon levels in your home)
- World Health Organization (Reference level for indoor radon)
- New Jersey DEP (Radon information: indoor pressure and backdrafting)
- Wisconsin DHS (Lowering your home’s radon levels)
- Minnesota Department of Health (Radon fan energy costs)
- HomeAdvisor (Radon mitigation cost)
- Bob Vila (Radon mitigation system cost)
- ANSI (ANSI/AARST SGM-SF-2023 soil gas mitigation standard)
- NRPP (Find a certified radon professional, US)
- C-NRPP (Find a professional, Canada)
