Why would anyone NEED a crawl space liner? That was my re-action when I began see information regarding this product/service a few years ago. But I have been convinced that providing this service has merit. If you have a home that is built on a SLAB or a raised open crawl space (such as a beach house), then crawl space liners are NOT applicable to your home. But IF your home has an ENCLOSED CRAWL SPACE, then I think you should continue reading.
The picture on left amplifies the height of most crawl spaces. The white material is the crawl space liner.
Crawl spaces are generally between 2 to 3 feet high. They commonly include foundation vents that allow outside air to penetrate underneath homes. Heating and air conditioning systems and/or ductwork are commonly installed in crawl spaces. So are plumbing drains and a lot of other “stuff” (including critters) concealed in crawl spaces. Crawl spaces are usually the one place that no-one enters except the service tradesmen. Typically, vapor barriers (plastic) are placed on the ground between the foundation wall and the pillars underneath the floors.
Unfortunately, many times crawl spaces are ill-prepared during construction and trap water. Or the crawl space may actually be lower than the outside level due to mulching activities from previous years and trap water…And then the condensation of summertime air conditioning (since most are partially covered with plastic) has nowhere to go. During the summer, due to the moisture from the ground and the moisture in the air, air handlers and the duct work “sweat” profusely. (It practically rains in crawl spaces when the summertime conditions are “right”. The “trapped” moisture and the water from condensation have nowhere to go since it is on top of a plastic moisture barrier.
Now, why is this bad? Mold and mildew thrive in the dark, damp climates (So do a lot of other critters that I choose not to name but Terminex and the “Snake Chaser” come to mind as potential sources to combat these other critters). The moisture content of the framing members (the floor trusts) become saturated with moisture and deteriorate rapidly (A politically correct way of saying “rots”). And the odors of the saturated ground seep inside the home from the crawlspace and contaminate indoor air quality.
Now…How does a crawl space eliminate all of the “things” referenced above? Crawl space liners prevent moisture from seeping through the foundation walls and the ground. With the addition of a de-humidifier (that is set to run only if the relative humidity exceeds a specified set point), the area underneath your home “dries”. After the initial moisture is removed, the de-humidifier removes the moisture that results from subsequent air conditioning. (If the humidity is removed, the air handler and the ducts don’t sweat so very little moisture is added to the sealed environment anyway.) Since the humidity is removed, mold and mildew will not grow and soon disappears. Since the humidity is removed, the moisture in the wood framing returns to a state that preserves the wood. Since the mold and mildew disappears and the contaminants (if any) from the ground have been sealed, there is less chance that air infiltration from the crawl space is contaminating indoor air. And lastly, this is a s-t-e-t-c-h but it’s true, the insulation requirements have been significantly reduced (the need for floor insulation is minimized because the temperature of the crawl space will be somewhere between ground temperature and the temperature setting of your thermostat). Crawlspace lines do reduce heating and cooling requirements.
I have been convinced that crawl space liners are NOT “snake-oil”. Properly installed they will work, protect your home, increase the longevity of air conditioning systems and ductwork, help sanitize indoor air quality and provide some reduction to heating and cooling costs. We would love the opportunity to install one for you.