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Crawl Space Door Systems, Inc.
5741 Bayside Road #105
Virginia Beach, VA 23455
Mon - Fri 8a.m. - 4p.m.

Vapor Barrier

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Vapor Barrier


  • 6 Mil Reinforced Crawl Space Vapor Barrier and 12 Mil Reinforced Vapor Barrier
  • aka: Moisture Barrier or "poly"
  • 6 Mil Reinforced is designed to last longer than non reinforced poly - We offer Clear Reinforced
  • 12 Mil Reinforced is the most common when doing an encapsulation - We offer Green / White. The white is normally what is face up when used in the crawlspace
  • 12'x 100' = 1200 square feet
  • 20'x 100' = 2000 square feet
Reinforced Vapor Barrier
6 Mil Reinforced

Crawl Space Vapor Barrier

What is a Crawl Space Vapor Barrier and when would I use one?

A vapor barrier is also known as “poly” or "moisture barriers." Most building codes now require vapor barrier in the crawlspace. 40% of moisture comes from the ground, therefore, the plastic is putting a barrier between the moisture that comes from the earth and the sub floor of your home. Poly is intended to retard the migration of moisture in your crawlspace.

What does Mil stand for and what’s the difference between them? What does reinforced mean?

Any vapor retarder that is not reinforced refers to the thickness of the plastic. Anything that is reinforced beyond 12 mil refers to the thickness of the fiber. The vapor barrier is reinforced to make it stronger so that it won't rip while you are moving around in your crawlspace.

Reinforced Vapor Barrier Encapsulation
6 Mil Reinforced Vapor Barrier 12"x100

Why is the 6 Mil clear and the 12 mil a solid color?

12 Mil is a stronger plastic and will last longer.  The difference in color you see from various 12 mil vapor barriers on the market only differs by who manufactures it and has no practical application.  When installing 12 Mil, you should always lay the side with color on the ground and leave the white side facing up.

What accessories help to lay poly and why are they necessary?

Poly Stakes: less work to keep the poly down versus using common insulation stakes/tiger teeth.

Use butyl tape and Christmas tree fasteners if you are encapsulating and bringing the vapor retarder up the wall or pillars.

Use Capped Vapor Barrier Stakes for a finished look and easier installation of the stakes. The Buttons are great for helping pound the stakes with a rubber mallet.

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5741 Bayside Road #105
Virginia Beach, VA 23455
Mon - Fri 8a.m. - 4p.m.


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