Radon mitigation cost
A radon system costs $800 to $2,500 installed and a test kit costs $15. Radon is the second leading cause of lung cancer in the United States, which makes the test the cheapest health decision a homeowner makes.
National average
$1,400
per project
A radon mitigation system costs $800 to $2,500 installed, typically around $1,400. A test kit costs $15 to $40 and takes three days. Given that radon is the second leading cause of lung cancer in the United States, the test is the cheapest health decision a homeowner makes.
Roughly one house in fifteen nationally is above the EPA action level, and in some regions it is one in three.
What it costs
| Item | Typical cost |
|---|---|
| Short-term test kit, DIY | $15 to $40 |
| Long-term test kit, 90 days or more | $25 to $60 |
| Professional test | $150 to $400 |
| Continuous monitor, homeowner device | $150 to $300 |
| Sub-slab depressurisation system | $800 to $2,500 |
| System in a house with multiple foundations | $1,500 to $4,000 |
| Crawl space membrane and depressurisation | $1,500 to $5,000 |
| Sump pit sealing and lid | $200 to $600 |
| Sealing floor cracks and penetrations | $200 to $1,000 |
| Passive system fitted during construction | $350 to $1,000 |
| Converting a passive system to active | $300 to $800 |
| Fan replacement, every 5 to 10 years | $150 to $500 |
| Post-mitigation retest | $50 to $200 |
| Running cost, fan electricity | $5 to $20 a month |
Testing, which comes first
Radon is a colourless, odourless radioactive gas from uranium decay in soil. It enters through cracks, the slab-wall joint, sump pits and any penetration.
Short-term test: 2 to 7 days, a charcoal canister or an electret, closed-house conditions. Cheap and quick, and it is a snapshot. Levels vary with weather, season and whether the windows have been open.
Long-term test: 90 days to a year, alpha track detector. More representative of your actual exposure and the better basis for a decision.
The EPA action level is 4.0 picocuries per litre, and the EPA notes there is no level known to be safe. Between 2 and 4, mitigation is worth considering.
Test the lowest lived-in level of the house. Test again after any foundation work, after finishing a basement, and every two years otherwise. Levels change.
How mitigation works
Sub-slab depressurisation is the standard system and it is more elegant than it sounds. A pipe is cut through the basement floor into the gravel beneath, a fan pulls a slight vacuum under the slab, and the soil gas is vented above the roof line instead of being drawn into the house.
It works because the house is normally at slightly lower pressure than the soil, which is what draws radon in. Reversing that pressure difference stops it at the source.
A correct installation includes:
- The suction point in the right place, sometimes more than one on a large or divided slab
- Sealing the sump lid, floor cracks and penetrations, so the fan is not just pulling basement air
- The fan in an unconditioned space, attic or outside, never in a basement, because a leak in the positive-pressure side would discharge radon into the house
- Discharge above the roof eave and away from windows
- A manometer on the pipe showing the system is running
- A retest afterwards, which is how anyone knows it worked
Systems typically bring levels down by 80 to 99%.
Frequently asked questions
Is radon really a serious risk?
The EPA attributes roughly 21,000 lung cancer deaths a year in the United States to radon, making it the second leading cause after smoking and the leading cause among non-smokers. It is one of the better-established environmental health risks.
Does my region have radon?
Every state has houses above the action level. Regional maps show tendencies rather than answers, and neighbouring houses frequently differ substantially. There is no substitute for testing your own.
Can I install a system myself?
The physical work is achievable and the design is not: suction point placement, fan sizing and sealing decide whether it works. Several states require licensed mitigators. Where DIY is permitted, retest afterwards without fail.
Does it come up in a sale?
Increasingly, yes. Many buyers test during the inspection period, and an unmitigated high result becomes a negotiation. Several states require disclosure of known results. A $1,400 system installed before listing removes the conversation.
What if I have a crawl space?
A sealed membrane over the soil with depressurisation underneath, $1,500 to $5,000. It also fixes the humidity problem most crawl spaces have, so it does two jobs.
Read next
Basement finishing cost$30 to $100per sq ftFinishing a basement costs $30 to $100 a square foot. It is the cheapest way to add living space to a house. A basement that gets wet cannot be finished until it does not.
Crawl space encapsulation cost$300 to $1,000per sq ftEncapsulating a crawl space costs $3 to $10 per square foot, averaging $5,500. In humid climates the vents code once required are actively delivering water into the space.
Crawl space repair cost$3 to $15per sq ftRepairing a crawl space costs $3 to $15 a square foot. The structural half decides the price, and it is the half nobody looks at until the floor sags.
Basement dehumidifier cost$200 to $3,500per eachA basement dehumidifier costs $200 to $500 portable or $1,500 to $3,500 installed. It is the right answer to a musty basement with no visible water, and the wrong answer to water on the floor.
Foundation inspection cost$300 to $1,000per eachA foundation inspection costs $300 to $1,000 from an independent inspector. Repair companies offer them free, and that is a sales visit that may also be a competent inspection.