ResourcesGlossary: fixing
Sub-membrane depressurization
Short answer
Sub-membrane depressurization, which EPA calls submembrane suction, is the radon fix for a crawlspace: the earth floor is covered with a high-density plastic sheet, and a vent pipe and fan draw the radon from under the sheet and vent it outdoors.
What sub-membrane depressurization means
EPA rates it plainly: when properly applied, submembrane suction is the most effective way to reduce radon levels in crawlspace homes.
The other fan option, which EPA calls less favorable, is active crawlspace depressurization, drawing air directly from the crawlspace. EPA says that technique generally does not work as well as submembrane suction.
What the reduction leaves from 6 pCi/L
EPA puts the typical reduction of submembrane depressurization in a crawlspace at 50 to 99 percent, and of natural ventilation in a crawlspace at 0 to 50 percent. Each row applies both ends of a range to a home that tests at 6
| Method | EPA's typical reduction | 6 pCi/L becomes, pCi/L |
|---|---|---|
| Submembrane depressurization | 50 to 99 percent | 3 to 0.06 |
| Natural ventilation of the crawlspace | 0 to 50 percent | 6 to 3 |
What it means for your home
A house with no basement can still have a radon problem, and this is the fix built for it: EPA's method for a crawlspace starts with the earth floor.
As with any active system, EPA says a warning device must be installed to alert you if it stops working properly.
Where to go next
- Radon mitigation cost estimator. Price a system for a crawlspace foundation in your state.
- Radon in a house without a basement. Why slab and crawlspace homes need testing too.