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Vapor Barriers
A crawl space vapor barrier is the foundation of every crawl space encapsulation system. It prevents ground moisture from rising into your home, protecting structural wood, insulation, and indoor air quality. Crawlspace Depot carries vapor barriers in a wide range of thicknesses and construction types, from lightweight non-reinforced poly to heavy-duty 20 mil reinforced and woven-coated rolls, so you can match the right product to your crawl space conditions. Need help choosing? Call us at 888-331-9991.
Not sure which vapor barrier is right for your crawl space? Read our Crawl Space Vapor Barrier Buying Guide to find the right type and thickness for your conditions.
What mil thickness should I use for a crawl space vapor barrier?
What mil thickness should I use for a crawl space vapor barrier?
Choosing a vapor barrier is a balance of durability, ease of installation, and cost. Smooth, debris-free ground may only require a lighter duty liner, while rough or rocky ground and crawl spaces with frequent foot traffic benefit from a more durable or thicker option. Greater mil thickness can improve durability, but construction matters too: non-reinforced, string-reinforced, and woven-coated barriers offer different levels of tear and puncture resistance. Our most popular choice is the 12 Mil Reinforced Vapor Barrier, which strikes a good balance for many encapsulation projects. For a detailed comparison, see our Vapor Barrier Buying Guide.
Is 6 mil vapor barrier enough for a crawl space?
Is 6 mil vapor barrier enough for a crawl space?
A 6 mil liner can be enough for basic ground coverage over smooth soil in a crawl space that receives little traffic. A 6 Mil Reinforced Vapor Barrier adds tear resistance, but thicker reinforced material is usually easier to install and maintain around rocks, piers, stored items, and service routes. Check local requirements and decide whether the project is simple ground coverage or a sealed encapsulation system which usually requires a more durable option.
What is the difference between reinforced and non-reinforced vapor barrier?
What is the difference between reinforced and non-reinforced vapor barrier?
Reinforced vapor barriers contain an internal skrim or grid that helps limit tearing and puncture growth. Non-reinforced liners are typically lighter and more flexible, which can be effective on smooth ground with little traffic, but damage can spread more easily if it catches on a rock or tool. Compare a 10 Mil Non-Reinforced Vapor Barrier with a 10 Mil Woven-Coated Vapor Barrier based on ground conditions, expected foot traffic, and crawl space construction, not thickness alone.
Is 20 mil vapor barrier worth it for a crawl space?
Is 20 mil vapor barrier worth it for a crawl space?
A 20 mil liner is most likely to earn its higher cost where the floor is rocky, equipment will be serviced regularly, non-flammable materials will be stored, or the liner must tolerate repeated crawling. The tradeoff is heavier material that costs more and can be harder to carry, unfold, and cut in low clearance. For a smooth, low-traffic floor, a lighter reinforced liner may be sufficient. A 20 Mil Reinforced Vapor Barrier can provide outstanding durability and protection, but just like all other vapor barriers, it is not a substitute for mitigation of standing water or drainage issues.
Should crawl space vapor barrier go up the foundation walls?
Should crawl space vapor barrier go up the foundation walls?
Yes. In a full encapsulation, the vapor barrier should extend up the foundation walls and wrap piers. A ground liner alone does not completely isolate the crawl space. Moisture vapor can migrate through porous masonry, water under hydrostatic pressure can seep through foundation walls, and ground moisture can enter around the unsealed edges of the floor liner. Extending the liner up the walls and sealing it to the ground liner creates a more complete moisture barrier. A Reinforced Translucent Wall Vapor Barrier can help preserve visibility for inspections. Leave a termite inspection gap between the top of the liner and the top of the foundation wall, as required by local code.