10/21/2026
Vented crawl spaces are doing damage to houses, and there's no way to sugarcoat it. The science is in, and the facts are confirmed: vented crawl spaces were never a good idea.
*There is data to support vented crawl spaces in the Pacific Northwest
If you've ever had to have foundation work done under your crawl space, more than likely it could have been prevented if the crawl space was encapsulated. If you've ever had mold or subfloor rot under your house, it would have been prevented if it had been encapsulated.
Encapsulation basically means bringing that space inside of the conditioned envelope, which means:
- Sealing it up tight
- Putting a v***r barrier down to stop moisture from coming up from the ground
- Putting in a dehumidifier to keep any moisture coming in through air leaks down
- In most cases, you'll need a perimeter French drain and a sump pump to capture groundwater and get it away from the house
If anyone tries to tell you otherwise, they are wrong. There is no data, science, or testing that shows that there's a good way to vent a crawl space, especially in a hot and humid climate in the summer here in Mobile and all along the Gulf Coast. You're attempting to dry a wet space with extremely wet air, and the only thing moving more air down there will do is possibly slow down condensation. Ultimately, it isn't going to work.
If you can't afford to encapsulate, you got to start saving now. Encapsulation takes some maintenance:
- You got to get down there and check the dehumidifier.
- You got to make sure the sump pump is working.
- You got to make sure anybody that works down there doesn't puncture the v***r barrier.
Even with that added maintenance, you're still better off than having gross, nasty, humid air from the crawl space getting into the house. If your house is old and you want it to last for another 50 years, this is going to have to happen. It doesn't matter if your house has good bones or not. If the foundation is bad, the whole house is bad.