Stop telling people to use moisture barriers on every crawlspace floor

I keep seeing people online say you absolutely need a 6 mil poly vapor barrier down in every crawlspace. But last month I pulled up a barrier that was laid down in a house built in 2019 here in Austin, and the soil underneath was damp and moldy because the plastic trapped moisture from the ground. The old school method of just letting the dirt breathe actually worked fine for decades before plastic became standard. I think we slap these barriers on without thinking about the local climate or drainage first. Has anyone else seen more problems than benefits from crawlspace vapor barriers in humid areas?

2 comments

2 Comments

lindaw1224d ago

Same thing happened to my buddy's house in Houston. 6 mil poly down, moisture got trapped underneath and he ended up with a musty smell in his living room after a year. It's like those air-tight food container lids that claim to keep stuff fresh but actually trap condensation if you don't dry everything perfectly first. People hear one solution works for dry climates or well-drained soil and just copy it without thinking. I see the same pattern with those "miracle" waterproof paints they sell at hardware stores - slather it on a damp basement wall and it just peels off because the real problem is water coming from the outside, not the paint. In Austin's humidity, letting the dirt breathe with good drainage and maybe a little gravel on top seems to work way better than sealing everything up tight. Honestly I think a lot of these building "rules" got made for colder northern states and folks just repeated them everywhere without adjusting.

nathanb7126d ago

6 mil poly vapor barrier" - you're telling me the dirt was moldy under that plastic?