Crawl space and slab radon mitigation
Crawl spaces, slab rooms and mixed foundations each need their own plan. Here's how radon companies approach them.
Plenty of Siouxland houses aren't a single tidy basement. An older Northside home might have a basement under the original house and a crawl space under a kitchen addition. A ranch in South Sioux City might be on a slab with a crawl space section. Radon can come in through any part of the house that touches soil.
How do you fix radon in a crawl space?
The standard method is sub-membrane depressurization. A heavy plastic membrane covers the soil, sealed at the seams and up the walls and piers. A pipe pulls from under the membrane and a fan sends the gas above the roof. It's the same idea as a sub-slab system, with plastic doing the job of concrete.
What about slab homes?
Slab-on-grade houses and additions use suction through the slab, often with the pipe routed through a closet, utility room or garage. Some need suction in more than one slab section, especially where a garage or addition was poured separately.
Mixed foundations
- Basement plus crawl space: often a sub-slab suction point tied to a membrane on one fan.
- Basement plus slab addition: may need a second suction point if the footing blocks airflow.
- Walkout lower levels: the slab may be partly at grade, which can change where the pit goes.
Can I just open the crawl space vents?
Ventilation sometimes helps a little, but it's unreliable, and in an Iowa winter it can freeze pipes and chill floors. Sealed-membrane suction is the dependable approach.
Anything else?
If you store things in the crawl space or need access to plumbing, ask how the membrane will hold up to foot traffic. A sealed membrane also keeps ground moisture down, which the crawl space will thank you for in a humid Missouri Valley summer.
The radon company prices the job after it understands your foundation, usually after a visit. We don't quote prices, and a number over the phone is only a ballpark, not a written bid.
Where we connect you with help
Common questions
Do houses with no basement get radon?
Yes. Any house in contact with the soil can. Test every home, whatever the foundation.
Does a crawl space system need a credentialed installer in Iowa?
Yes. Iowa requires an Iowa HHS credential for anyone mitigating radon for a fee.
Related services
More background: Siouxland radon guide.
Radon number higher than you hoped?
Call and a local radon mitigation company will look at the house and quote a system.