5 Steps to Install a Vapor Barrier in Your Foundation

What You'll Need
1/3 cup of laundry detergent
1 part chlorine bleach
3 parts warm water
Rubber gloves
Eye protection
Face mask
A dehumidifier
Enough polyethylene sheeting to cover the entire foundation
6-inch turf staples

A vapor barrier is a layer of protective material laid across the foundation of a house, insulating it from the effects of moist air that can carry mold and other harmful particles, causing moisture damage and wood rot on the fixtures.

Step 1 - Clear the Air

A lack of ventilation in an area can cause "moisture pockets" in the space; these are places where mold can form. To prevent these, check the area for any ventilation ducts, making sure they are clear of debris or plant life that could block air circulation.

Step 2 - Get Rid of Mold

When applying a vapor barrier to your home, the first step is to clean the foundation area fully. Put on your safety gloves so you can take a bucket and mix laundry detergent, bleach, and warm water together. You'll be working with mold particles and bleach in a confined space, so wear a dust mask and safety glasses, too. When the mixture is finished, apply it to the mold with the sponge and scrub until the area is clean.

Step 3 - Dry It Out

If you have access to a dehumidifier, place it within the foundation area to extract any remaining moisture before continuing. Place the humidifier on a cinder block or wooden plank for better circulation and then run a hose-pipe from the vent in the machine to an outside area. Take care to ensure the hose is always aiming downwards and doesn't snake over any obstacles. Most dehumidifiers drain water via gravity, and obstacles would prevent this. You may need to leave the humidifier there for a day or two.

Step 4 - Put Down the Sheeting

Once the area is dry, apply polyethylene sheeting to the ground, making sure every part of it is covered. If you are using more than one sheet, make sure they overlap by at least six inches to prevent leakage. The sheeting should rise up the walls slightly, but not too much. Once the polyethylene is laid, take the turf staples and hammer them into the sheeting, with one staple every 8 feet or so, forming a grid that holds the sheeting in place.

Step 5 (Optional) - Add Sand

As an additional barrier, throw down a thin layer of sand on top of the polyethylene. Should any moisture escape through the polyethylene sheeting, the dry sand will catch and hold it. It will also help smooth out the layer of sheeting.