Radon Mitigation Methods Compared: Sub-Slab vs. the Rest
Sub-slab suction against drain-tile, sump, block-wall, crawlspace, sealing, pressurization and HRV methods: radon reduction, installed cost and running cost, side by side.
Active sub-slab suction is the method most homes end up with. EPA's Consumer's Guide calls it "the most common and usually the most reliable radon reduction method," and its cost table credits it with a 50 to 99 percent reduction. The other methods either suit a particular foundation (drain tiles, a sump, hollow block walls, a dirt crawlspace) or play a supporting role (sealing, ventilation, pressurization). This page puts them side by side so you can tell whether a bid is proposing the right system for your house.
Two kinds of price figures appear below. EPA's table is from the January 2010 edition of the Consumer's Guide (EPA 402-K-10-002), so its dollars are 2010 dollars. HomeGuide's February 2026 survey is the most recent published set of installed prices we have found; it covers the soil-suction methods but not ventilation or pressurization. Where only EPA has a number, we say so.
The comparison at a glance
| Method | Radon reduction (EPA) | Installed cost, EPA (2010 dollars) | Installed cost, HomeGuide (2026) | Yearly running cost, EPA (2010 dollars) |
|---|---|---|---|---|
| Active sub-slab suction | 50 to 99% | $800 to $2,500 | $1,200 to $2,000 | $50 to $200 |
| Passive sub-slab suction | 30 to 70% | $550 to $2,250 | not listed | some energy penalty |
| Drain-tile suction | 50 to 99% | $800 to $1,700 | $900 to $1,800 | $50 to $200 |
| Sump-hole suction | 50 to 99% | $800 to $2,500 | $900 to $2,500 (sump sealing) | $50 to $250 |
| Block-wall suction | 50 to 99% | $1,500 to $3,000 | $1,800 to $3,000 | $100 to $400 |
| Crawlspace submembrane suction | 50 to 99% | $1,000 to $2,500 | not listed | $50 to $250 |
| Crawlspace natural ventilation | 0 to 50% | none, or $200 to $500 for added vents | not listed | some energy penalty |
| Sealing entry routes | used with other methods | $100 to $2,000 | not listed | none |
| Basement pressurization | 50 to 99% | $500 to $1,500 | not listed | $150 to $500 |
| Heat recovery ventilator (HRV) | variable | $1,200 to $2,500 | not listed | $75 to $500 |
Reduction, EPA cost and running cost columns: EPA Consumer's Guide to Radon Reduction, Installation and Operating Cost Table (2010). 2026 column: HomeGuide, Radon Mitigation Cost (Feb 5, 2026).
Sub-slab suction: the default for basements and slabs
A contractor drills one or more holes through the floor slab, sets a pipe into the gravel or soil underneath, and runs it to a fan that exhausts above the roofline. The fan keeps the space under the slab at lower pressure than the house, so soil gas is pulled out before it can seep in. EPA notes that often only a single suction point is needed; how many depends on how easily air moves through the material under the slab, which a contractor can check with a soil communication test (a vacuum in one hole, smoke at another).
The price spread comes mostly from the number of suction points, the pipe route (an exterior wall is usually simpler than threading pipe through closets to the attic), and how much sealing the slab needs. HomeGuide puts a typical system at $1,200 to $2,000 with a national average of $1,600; EPA's 2010 figure for the same work was $800 to $2,500, with an average of about $1,200 across all systems.
When a different suction point makes sense
- Drain-tile suction. If the house already has perforated drain tile around or under the footing, the contractor can draw suction on that loop. EPA says it works with either a partial or complete loop. HomeGuide prices it at $900 to $1,800, slightly below a standard sub-slab system.
- Sump-hole suction. A basement sump can be capped with an airtight lid so it still drains water and doubles as the suction point. EPA notes it works best when air moves easily from under the slab to the sump. HomeGuide's range for sump sealing is $900 to $2,500.
- Block-wall suction. Hollow concrete block foundation walls can carry soil gas up inside the cores. Block-wall suction depressurizes the wall itself and is often paired with sub-slab suction. It is the priciest soil-suction method in both data sets: $1,500 to $3,000 in EPA's 2010 table and $1,800 to $3,000 in HomeGuide's 2026 survey. EPA lists the yearly running cost at $100 to $400, higher than sub-slab suction, and notes it requires sealing of major openings.
- Crawlspace submembrane suction. For a dirt-floor crawlspace, EPA describes covering the ground with a high-density plastic sheet and drawing suction under it, and calls this, when properly applied, the most effective way to reduce radon in crawlspace homes. EPA's 2010 range is $1,000 to $2,500.
Methods that support a system rather than replace it
Sealing. Sealing cracks and openings makes suction systems work better and cuts the loss of conditioned air, but EPA does not recommend sealing alone, because by itself it "has not been shown to lower radon levels significantly or consistently." Normal settling opens new cracks. A bid that is mostly caulk and no fan deserves a second opinion.
Ventilation. Opening windows and vents dilutes radon, but EPA says levels most often return to previous values within about 12 hours of closing up, so it treats natural ventilation as temporary. Crawlspace vents can help a little (0 to 50 percent in EPA's table) and may require insulating pipes in cold climates.
Pressurization and HRVs. Basement pressurization pushes air into the lowest level to keep soil gas out; EPA lists a 50 to 99 percent reduction but says it should only be considered after the more common techniques have not worked, because results depend on how tight the basement is and on doors and windows staying shut. A heat recovery ventilator trades stale indoor air for fresh outdoor air while recovering heat; EPA describes its use as limited and best suited to a basement, with running costs of $75 to $500 a year in 2010 dollars.
How to choose, step by step
- Step 1: Confirm the result. EPA recommends fixing a home when one long-term test, or the average of two short-term tests, reads 4 pCi/L or more. See what to do after a high radon test.
- Step 2: Identify every foundation type in the house. EPA notes that a basement under part of the house with a slab or crawlspace under the rest may need a combination of techniques.
- Step 3: Ask each bidder which method they propose and why. A good answer names the suction point, the fan location, the pipe route and any diagnostic tests.
- Step 4: Compare the bids line by line against the published ranges above and the radon mitigation cost calculator.
- Step 5: Retest after installation, within 30 days but no sooner than 24 hours after the fan starts (EPA).
Questions
Is a passive system enough?
Usually not on its own. EPA's table gives passive sub-slab suction a 30 to 70 percent reduction against 50 to 99 percent for active suction, and says a fan can be added to an existing passive pipe for about $300 (2010 dollars).
Which method is cheapest to run?
Among the fan systems, sub-slab and drain-tile suction have the lowest yearly cost in EPA's table, $50 to $200. Block-wall suction runs $100 to $400 and pressurization $150 to $500, all in 2010 dollars.
Can one house need two methods?
Yes. EPA notes block-wall suction is often combined with sub-slab suction, and mixed foundations may need a crawlspace membrane plus a slab suction point.
Next: price your system in the radon mitigation cost calculator, read the radon mitigation cost guide, or check your area in radon levels by ZIP code.
Sources
- EPA, Consumer's Guide to Radon Reduction (2010 edition, archived)
- EPA, How much can a radon mitigation system cost?
- EPA, A Citizen's Guide to Radon (2016)
- HomeGuide, Radon Mitigation Cost (Feb 5, 2026), cited as text
Prices are published ranges from the sources listed on this page; anything we calculated is labeled as an estimate. Get at least two itemized bids from certified or licensed mitigators. Run the calculator to build your own range.