What is the required thickness of the polyethylene sheeting for crawlspaces?

The required thickness of polyethylene sheeting for crawlspaces is typically established as 6 mil. This thickness offers a balance of durability and cost-effectiveness, making it suitable for ground moisture control and vapor barrier applications in residential construction. A 6-mil polyethylene sheet is sufficiently thick to resist punctures and tears from underlying surfaces such as soil or gravel while providing an effective barrier to moisture infiltration.

Using a thicker sheet, such as 8 mil or 10 mil, may provide additional durability, but they are not typically required and can add unnecessary costs. On the other hand, a sheet that is too thin, like 4 mil, may not provide adequate resistance against variables like soil movement, which could compromise its effectiveness over time. Therefore, 6 mil has been generally accepted as the standard in the industry for many crawlspace applications.