How to Reduce Radon Levels in Your Home (DIY & Pro Options)

Step 1: Confirm Your Radon Levels First

Before you start reducing radon, you need to know exactly what you're dealing with. The EPA recommends action if your home tests at 4 picocuries per liter (pCi/L) or higher—that's the point where health risks become significant.

Use an EPA-approved radon test kit (passive or active) to get a baseline measurement. Passive kits like charcoal canisters cost $15–$30 and require a 2–7 day exposure; active kits use electronic detectors and cost $100–$300 but give faster results. Place the test kit in your lowest occupied room (usually the basement) away from drafts and exterior walls for the most accurate reading.

If your initial test shows levels at 4 pCi/L or above, take a second test before spending money on mitigation. This confirms the problem isn't a one-time spike from weather changes.

Step 2: Seal Foundation Cracks and Gaps (DIY-Friendly)

Radon seeps into your home through tiny cracks, gaps around pipes, and pores in your foundation. Sealing these entry points won't eliminate radon entirely, but it can reduce levels by 20–50%—sometimes enough on its own.

What to Seal:

• Visible cracks in concrete — Foundation walls, floor joints, sump pump openings
• Gaps around utilities — Where water pipes, electrical conduits, and HVAC lines enter the house
• Rim joists — The seam where your basement walls meet the house frame
• Sump pump covers — These are major radon entry points; use a solid (not sump pump pit lid) cover
• Unsealed earth in crawl spaces — Use polyethylene sheeting or pour concrete over exposed soil

Materials and Costs:

DIY sealing typically costs $200–$500 in materials and takes a weekend. Start in your basement or crawl space and work systematically. Use a caulking gun for precision, and apply expandable foam generously—it shrinks slightly as it dries.

After sealing, wait at least 48 hours (ideally a week) before re-testing. Weather, seasonal pressure differences, and foundation settling can all affect results, so multiple tests over time give you the clearest picture.

Step 3: Improve Home Ventilation

Radon concentrations are highest in poorly ventilated spaces because the gas has nowhere to go. Increasing air exchange dilutes radon and pushes it outdoors before it accumulates to dangerous levels. This won't eliminate radon alone, but it's a powerful complement to sealing.

DIY Ventilation Improvements ($200–$800):

• Open basement windows and doors regularly — Even 15 minutes of fresh air exchange lowers radon levels temporarily. Not a permanent fix, but free and immediate.
• Run exhaust fans continuously — Bathroom and kitchen exhaust fans remove stale air. Keep them running 8+ hours daily; some homes benefit from a dedicated basement exhaust fan ($80–$200 installed).
• Use window box fans — Position a box fan in a basement window to pull outdoor air indoors. Costs $30–$60 and works well in warmer months.
• Install a heat recovery ventilator (HRV) — These systems exchange indoor air with outdoor air while recovering heat/cooling energy. More expensive ($1,000–$2,000 installed) but highly effective and energy-efficient for year-round use.

For detailed guidance on home ventilation techniques , check our full ventilation guide. Increasing air exchange also improves overall indoor air quality by reducing not just radon but moisture, odors, and allergens.

Step 4: Professional Radon Mitigation Systems (Most Effective)

If your DIY efforts don't lower radon to safe levels, professional mitigation is your next move. Active soil depressurization (ASD) systems are the gold standard—they pull radon-laden soil gas from beneath your foundation and vent it safely above your roofline.

How Professional Mitigation Works:

A certified radon contractor installs a PVC pipe system in or around your foundation to capture soil gas before it enters your home. A small fan (usually 40–80 watts) continuously pulls air from beneath the house and exhausts it through a vent pipe extending 12+ feet above the roofline. This creates negative pressure under the foundation, preventing radon from rising into the living space.

Effectiveness: Professional ASD systems reduce radon by 85–99%—often bringing high levels down to 1–2 pCi/L.

Cost: $800–$2,500 depending on your home's size, foundation type, and radon level. Expect $1,200–$1,800 as a typical range.

When to Call a Professional:

Contact a radon mitigation professional if:

• Your home tests above 4 pCi/L even after sealing and ventilation improvements
• You have a crawl space or sump pump (these require specialized systems)
• You want a permanent, low-maintenance solution
• You're selling your home and radon disclosure laws apply in your state

Licensed contractors typically offer a post-installation test (included in price) to verify the system works. Most systems include 5–10 year warranties on parts.

Comparison: DIY vs. Professional Mitigation

Other Radon Reduction Strategies

Depressurize Your Sump Pump: If you have a sump pump