Which Radon System Fits Your Foundation?
Not sure which radon system your house actually needs? No single design works in every Des Moines house.
Residential radon mitigation starts with your foundation. We look at how your home sits on the ground, then match the system to it.
The odds are good that you need one. The Iowa Radon Survey found that 71.6% of Iowa homes sit above the EPA action level of 4 pCi/L, and the EPA rates all 99 Iowa counties as Zone 1, its highest radon potential.
Here’s how the five residential system types line up.
| Foundation or situation | System we usually recommend | What it involves |
|---|---|---|
| Basement or slab-on-grade | Sub-slab depressurization (SSD) | One or more suction pits cored through the slab, sealed PVC pipe, fan above living space |
| Dirt or gravel crawlspace | Sub-membrane depressurization (SMD) | 10-20 mil poly vapor retarder sealed to walls and piers, suction pulled from under the membrane |
| Finished basement you don’t want to open up | Exterior radon system | Suction through the rim or slab edge, pipe and fan on the outside wall, exhaust above the roofline |
| Private well with high water radon | Waterborne radon system | Aeration or point-of-entry treatment that strips radon from water before it reaches taps |
| Soil vapor concerns beyond radon | Residential vapor intrusion system | Same depressurization approach, designed for chemical vapors as well as radon |
Many older Des Moines homes mix these. A 1920s house might have a partial basement next to a dirt crawlspace, and a split-level in Urbandale or Johnston can have two or three separate slabs. In those homes we often tie more than one suction point into a single fan.
Do you run a childcare center? Under Iowa Administrative Code 441-109, licensed centers must test for radon within a year of opening and mitigate if results top 4.0 pCi/L. Send us your result and we’ll sort out the right fix.
What Is Sub-Slab Depressurization?
Sub-slab depressurization is the most common radon fix in Iowa. We core a hole through the basement floor, dig out a small suction pit underneath, and connect it to a sealed pipe.
A radon fan such as a RadonAway RP145, GP501 or Fantech Rn2 creates steady suction under the slab. Soil gas follows the easiest path, which is now the pipe instead of your basement. The Minnesota Department of Health notes that a quality system can bring year-round levels below 2 pCi/L, well under the 4 pCi/L action level.
Pressure field extension tells us how far that suction reaches. Here’s what we usually see:
- Clean gravel under the slab: often one suction point is enough.
- Tight clay: suction travels less far, so you may need two points.
- Interior footings: these split the soil gas flow, so they may need their own point too.
We test this with a small drilled hole and a micromanometer before we commit to a design.
Why sealing matters
Suction works best when the slab is tight. We seal the floor-wall joint, open cracks and the sump pit with polyurethane sealant and a gasketed lid. It’s part of every install because leaks steal suction from the system. Minnesota’s health department says the same: sealing limits radon flow and makes the system more efficient.
How Much Does Radon Mitigation Cost in Des Moines?
We don’t publish one flat price, because the same price can’t fit a 900-square-foot ranch and a 4,000-square-foot walkout. These are the factors that move a quote up or down:
- Foundation type. A single basement slab is the simplest. Crawlspaces add membrane material and labor.
- Number of suction points. Split-levels, additions and homes with interior footings may need more than one.
- Routing. Interior pipe through a garage or closet versus exterior pipe up the side of the house.
- Fan model. Tight soils need a higher-suction fan. Gravel needs less.
- Sealing scope. Open sumps, block walls and large cracks take more time to seal.
- Electrical. Most fans need a dedicated outdoor-rated disconnect or outlet near the fan.
For a national ballpark, Angi’s 2026 cost data puts most radon systems between $800 and $1,300. Simple installs start near $400, and complex homes can reach $2,500. Your quote will land inside that spread based on the factors above.
Send us your test result and a few photos of your basement or crawlspace and we can usually give you a written quote without a site visit. For a deeper look at statewide cost drivers, read our guide on radon mitigation cost in Iowa.
Common Problems We Solve
Finished basements
You don’t have to tear out drywall. We find an unfinished corner, a storage room or a utility closet for the suction point, or we go exterior. The pipe can run through a closet chase or up through the garage into the attic.
Open sump pits and drain tile
Many Des Moines basements have a sump pit tied to perimeter drain tile. That tile can carry soil gas right into the house.
We seal the pit with an airtight lid and often use the drain tile itself as part of the suction field. Drain tile suction is one of the three most common system types listed by the Minnesota Department of Health, so it’s a well-proven approach.
Old block and fieldstone foundations
Hollow block walls and rubble foundations leak soil gas through the walls as well as the floor. These homes may need wall sealing or a second suction point. We’ll tell you up front if your foundation needs extra work.
Combustion appliances
A strong fan can, in rare cases, affect how a furnace or water heater drafts. We check the combustion appliance zone (CAZ) for backdraft when the system starts up, so the fix for radon doesn’t create a new problem.
The check follows the EPA Radon Mitigation Standards. We close the windows and doors, run the exhaust fans, wait five minutes, then use a smoke tube or carbon dioxide analyzer to look for flue gas spilling near the vent hood.
Interior vs. Exterior Routing
Both work. Interior routing keeps pipe out of sight on the outside of the house and protects it from Iowa freeze and condensation. Exterior routing avoids opening ceilings and is often the best choice for finished basements.
We compare looks, noise and winter performance in our guide to interior vs. exterior radon mitigation.
Whichever route you choose, the exhaust must end above the roof edge and away from windows, doors and vents so radon can’t come back in. Iowa’s mitigation rules follow the EPA standards, which call for the discharge point to be:
- Above the eave of the roof.
- At least 10 feet above ground level.
- At least 10 feet from any window, door or opening less than two feet below the exhaust point.
- At least 10 feet from any opening into an adjacent building.
Proof the System Worked
A radon system isn’t finished when the fan turns on. We run a post-mitigation test at least 24 hours after startup, under closed-house conditions, and give you the before-and-after numbers. North Carolina’s radon program puts the window at no sooner than 24 hours and no later than 30 days after activation, with the house closed up for at least 12 hours beforehand.
You’ll also have a U-tube manometer on the pipe. If the liquid levels are uneven, the fan is pulling suction. If they’re even, call us.
Retest every two years, and after big changes like finishing the basement or replacing the furnace. That two-year rhythm is standard advice from state radon programs, and it catches a failing fan before it becomes a health problem.
Ready to get residential radon mitigation moving? Book a radon test or request a quote with your current result. You can also see how our Des Moines radon mitigation team covers testing, commercial work and long-term maintenance.
