Preventing Mold and Mildew Using House Wraps and Vapor Barriers

Mother Nature can play havoc with a house, especially when it is being remodeled with a new addition or under construction. Taking the necessary steps for weather proofing and moisture-proofing your home is essential for protection against mold and mildew, as a house under construction rarely escapes rain, fog, or high humidity. Even when the work is done the weather can be relentless with high winds, changing temperatures, and of course, snow and ice.

One of the best-known brands of house wrapping is Tyvek, which is made by DuPont. According to the company specifications, Tyvek is made from very fine, high density polyethylene fibers. It is a durable plastic-like material that is an impervious moisture barrier. Since moisture is the key component of mold and mildew, installing a house wrap is invaluable in its prevention.

Homes with crawl spaces have particular moisture problems. Mold in air conditioning ducts are common and can result in musty odors brought into the home as well as aggravating allergies and other health issues. Proper heating, ventilation and air conditioning (HVAC) duct construction and a crawl space vapor barrier help to eliminate and retard mold growth.

When sealing a crawl space against moisture, it is best to use a 10 to 20 mil plastic vapor barrier. Typically, a 16 mil thickness in size is heavy enough to resist punctures that can occur during installation. Vapor barrier materials are available at most home centers and hardware stores.

When installing vapor barriers in a crawl space, overlap each section 12" inches or more and attach a small strip of duct tape every 36" inches along the seam to keep them in place and prevent gaps. Turn the vapor barrier up the wall about 8" inches making certain that there is contact between the barrier and the wall. If there are vents to the outside, these must be closed to prevent humidity from the outside from getting into the crawlspace. Condensation occurs when the warmer outside air comes in contact with the cooler surface of the air conditioning ductwork.

If the foundation of the home is a concrete slab, insulate the perimeter of the slab using 1" thick extruded polystyrene foam board. Install the foam board between the outer edges of the slab and foundation. It should extend vertically 4" inches and 24" inches horizontally under the edge of the slab.

Preventing mold and mildew in the home begins with keeping the moisture out and keeping the inside dry. All the right materials can be found at the local hardware store and home center along with further advice concerning any particular need your home may have.

Remember, always work safely.