How to Install a Crawl Space Vapor Barrier

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What You'll Need
10-mm plastic
Utility knife
Extension cord
Staple gun

Crawlspace vapor barriers are sometimes needed beneath a home or trailer, where skunks and small animals sometimes seek the darkness. Neighborhood dogs take meat and small animals into such spaces. All these things can create unpleasant odors which seep through the floor.

When that happens, you must seal the space with a vapor barrier between your crawlspace and your home. All you will need are a few simple materials and some usable suggestions, such as the 6 steps below.

Step 1 - Purchase a Roll of Thick Plastic

10-mm plastic sheeting is usually sufficient to keep odors from seeping into your home. Buy a roll of this plastic sheeting at your hardware store or home improvement center.

The plastic vapor barrier comes either clear or black. Both will equally shield your house from odors and moisture, but if in the future you may need to install phone or data cables or additional water and natural gas pipes, then you should use the clear plastic.

Step 2 - Create Light to See In Your Dark Space

You'll need light to see in the dim space below your house. A flashlight will work, but you'll need to use both hands to cut and attach the plastic, so a drop light will be much better. There are no power outlets in your crawlspace, so you'll need an extension cord long enough to reach from your crawlspace to an outlet in your house.

Step 3 - Examine Your Crawlspace

If you haven't been under your house for some time, you should carefully examine the space for sharp objects on the ground or metal edges on heating and air conditioning units.

Step 4 - Measure Space Where You Will Need the Plastic Strips

Measure both the length and width of your crawlspace. Then measure the width of your plastic sheeting. Some of these plastic rolls have layers of plastic that are doubled and are only half as wide as the sheet itself. Rather than measuring the width of the roll, measure the width of the actual sheet.

Step 5 - Cut and Attach the Plastic Sheeting

When cutting the plastic sheets to fit, make allowances for objects such as plumbing pipes and heating ducts. Where you find it necessary to cut around these objects, be sure to tape irregular edges of your plastic sheeting to close any voids. Staple the plastic to wood surfaces. If you don't have enough wood surfaces, use duct tape on the metal surfaces.

Step 6 - Close Entrances to Your Crawl Space

If there are open entrances to your crawl space that might allow animals to enter, close them spaces by fitting pieces of plywood, carpeting, or plastic over the opening.