How thick does the vapor barrier need to be?

Vapor barriers should be at least 6mm in thickness to effectively cover the area and create a moisture barrier. Triangle Crawl Space Solutions uses both a 6mm material for simple vapor barrier installation and a thicker more durable 10mm vapor barrier material depending on the budget and needs of the home.

More common that an issue with the thickness of the vapor barrier is making sure that the vapor barrier is properly installed and is covering the entire area under your home. If the vapor barrier doesn't extend all the way to foundation walls or has gaps in the coverage then moisture simply moves around the barrier and impacts the uncovered area.