Purpose of a Vapor Barrier Floor
One of the most important but most overlooked portions of a floor is the vapor barrier. It only takes a few minutes to lay down and is inexpensive, but it can also save you a lot of money in the long run. Much of the damage that appears below the surface of the floor can be avoided by installing a vapor barrier.
Cool Air Exchange
When a floor is laid over a garage, many municipalities have zoning regulations against not having a vapor barrier. The object of the vapor barrier in the garage is to reduce the amount of cold air exchange. When a garage door is opened, cold air seeps through the floor into the room above, making that room cooler. Normally, these vapor barriers are placed above the drywall in a finished garage or hung to the rafters in an unfinished garage. However, if you're having the house built or are replacing the floor, you can have the vapor barrier put under the floor.
Moisture
The vapor barrier also reduces the buildup of moisture under the floor. This is important because that moisture will actually damage the underside of the floor. This is particularly true if it's a wooden floor. These vapor barriers are waterproof because they're made of plastic.
Insect Infestation
Another aspect of vapor barriers is stopping insect infestation. Again, this is important to a room that has direct access to to the outside. Insects will not eat through plastic or come through the plastic unless there is a gap or hole. One of the common insects that swarms is the ant. Ants will come up anywhere in a home to swarm if there is access to the home. A vapor barrier reduces this problem.
Cushioning
A vapor barrier also provides a cushion. The barrier used on a wooden floor is only a 1/16th-inch thick, but it still provides enough cushioning to keep the floor from shattering or splintering. The most common form of cushion and vapor barrier is the carpet padding. Carpet padding has a thin plastic vapor barrier on the bottom along with a 1/2 inch to 1 inch of padding.
Floating Floors
These are floors such as Pergo or other brands that use a slick-covered padding that allows the floor to expand and contract naturally. These are low-friction vapor barriers designed specifically for floating floors. Floating floor do not need to be nailed or glued down, thus the term.