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What Crawl Space Vapor Barrier Thickness Do I Need?

It’s a common question I get and rightfully so, right? After all, you want to make sure you get the right vapor barrier size as I’m sure you don’t want to go through the process of choosing the wrong one. Trust me, you don’t.

How can you make sure you get the right vapor barrier thickness?

Simple, know what the thickness means and why.

20 Mil Liner

The 20 mil crawl space vapor barrier is the thickest you can get. It’s meant to be thick so it can protect your encapsulation. The 20 mil liner is commonly used on the crawl space floor.

Crawl Space Floor – Rough, hard and rocky

Traffic And Storage – Ok for storage and foot traffic

12 Mil Liner

The 12 mil crawl space vapor barrier is the 2nd largest thickness and is most commonly used on the crawl space walls.

Crawl Space Floor – Hard, some small rocks

Traffic And Storage – Some foot traffic and storage is ok

8 Mil liner

The 8 mil crawl space vapor barrier is one of the smallest thickness you can get. The 8 mil liner is commonly used in small crawl spaces.

Crawl Space Floor – Smooth and no rocks

Traffic And Storage – Very little foot traffic and storage, recommend none

6 Mil liner

The 6 mil crawl space vapor barrier is the smallest thickness you can get for the crawl space. The 6 mil liner is commonly used in small crawl spaces.

Crawl Space Floor – Smooth, no rocks

Traffic And Storage – No foot traffic and storage

Vapor Barrier Thickness

The crawl space vapor barrier thickness you need depends on the type of crawl space environment you have.

If you have a hard rocky crawl space floor, it’s safer to choose a thicker vapor barrier.

If your crawl space floor has no rocks or pointy objects, a smaller thickness can work.

Don’t forget about storage and foot traffic. If you’re going to store items on the crawl space, consider a thicker vapor barrier.