Crawl Space Vapor Barrier Types

Before selecting the best crawl space vapor barrier for your home you must first understand what it is you expect it to do during its service life. There are 4 main parts to a successful crawl space vapor barrier:

• Moisture protection
• Durability
• Longevity
• Value

Specialty products like crawl space vapor barriers, must perform under difficult conditions. That does not mean that every crawl space vapor barrier will be installed in a difficult condition, but it does mean the vapor barrier must be capable of handling the worst in order to be the best.

String Reinforced Polyethylene Vapor Barriers

The first type and the most popular crawl space vapor barrier is the reinforced polyethylene plastic film. This engineered plastic film is the most widely used and the  very durable, offering the long service life and dollar for dollar a good value. This of course assumes the vapor barrier is made to high quality standards.

Uneinforced Polyethylene Vapor Barriers

As the name implies, this vapor barrier, is without any reinforcements and is made from polyethylene as well. Because it is manufactured without any reinforcement, it is a bit less durable in a crawl space environment. However, experience is now showing a high quality, virgin, non reinforced vapor barrier that is 10 mil or thicker can provide a service life equal to a reinforced barrier.

Coated Woven Crawl Space Liners

This product can be considered a vapor barrier, but most often it is a vapor retarder (see the difference here). The reason is because the center is woven polyethylene ribbons (like a tarp) and then coated with a thin, 1 mil, layer of clear or colored polyethylene on both sides. The woven ribbons make this product extremely strong, but one scrape by a sharp rock and the outer layer of film is compromised.

Hybrid Woven Crawl Space Liners

This crawl space liner uses the ribbon reinforcement of the coated woven and the film layers of a string reinforcement that makes a product that outperforms both. The strengthened polyethylene ribbons improve the puncture and tear strength of the barrier to 3x stronger than string reinforced and the film layers improve the moisture protection over the coated woven. 

Plasticized Aluminum Liners

This type of product is new to the crawl space scene. It is a mixture of a thin coated woven liner (3 Mil including the outer layers on one side), open cell foam(center) and a plastic film with some aluminum mixed in (1.5 Mil on the second side). This product boasts 0 perm rating because of the “aluminum” layer, but the reality seems to be far from that. Even if this product was a 0 perm, the installation would not be. I mean the 0 perm would be compromised with the tape seams, supports, and workmanship. Even if we allowed this products only claim to fame (0 perm) its very thin outer layers would prevent this product from performing due to its very low durability.