Crawl Space Restoration:

What is the purpose of installing a Vapor Barrier?

Vapor barriers, also referred to as moisture barriers, are simply a sheet of polyethylene plastic laid on the dirt surface of a crawl space. The vapor barrier prevents moisture in the ground from penetrating into the crawl space area and potentially damaging the exposed wood and insulation. It encourages moisture to drain into the soil, so there is not a layer of water trapped just below your crawl space for long periods. It also helps control humidity levels in your crawl space. In addition a properly installed vapor barrier also guards against any crawl space moisture from becoming a breeding ground for mold and a host of other problems

How is the vapor barrier installed?

Proper installation is critical. The vapor barrier needs to cover all of the dirt completely and also be properly sealed. In addition the concrete footing and at least part of the foundation wall need to be covered as well. Some homeowners prefer to cover the entire foundation wall. This helps prevent any moisture from escaping and also give the space a uniform look. We tape all of the seams using a polyethylene UV resistant tape. This will give the vapor barrier a water proof seal at the seams.

The polyethylene plastic needs to be attached firmly to the concrete foundation wall and any concrete piers. We use a double sided aggressively reinforced black butyl rubber tape. The key is that it is non hardening and remains flexible and sticky during all seasons in the northwest. In addition we drill ¼ inch holes in the foundation every 2 -3 feet and install Foundation Pins to permanently secure the Vapor Barrier to the foundation wall. This will ensure that year after year the vapor barrier will still be attached to the foundation walls.

Some contractors use adhesive caulks to “glue” the polyethylene to the foundation. This method may work fine during the warmer summer months but the caulk tends to harden over time, especially during the winter months and can potentially detach from concrete surfaces. Ask your contractor what they are using to secure the vapor barrier to your foundation wall. Every professional uses a mechanical fastener.

What is the difference between a 6 mil, 10 mil., 12 mil. or a 20 mil. vapor barrier?

This number refers to the thickness of the plastic. To be more precise, 6 mil means 6 millimeters or 0.006 inches thick. The thickness of the product adds to the life expectancy of the vapor barrier. The standard vapor barrier has always been black 6 mil In Washington State. This is the minimum to meet current building codes. Truth is this is a relatively thin product that tears easily and probably won’t last over time. It can be purchased at most hardware stores for about $70.00 per 1000 square feet.

There are, however, 10 mil and 12 mil products on the market today that have excellent vapor retardant capabilities and are tear resistant. Our technicians have samples of these so you can see for yourself the differences.

We believe that if you are paying for a premium crawl space restoration it make sense to use a better quality product that truly will stand the test of time not to mention it looks absolutely fantastic. Before you hire a crawl space contractor ask them what product they use and ask to see samples of their different products so you can decide for yourself.

What is the best vapor barrier for your home?

It depends on your needs. How often are you in your crawl space? Do you use it for storage or other purposes? Is your furnace or other appliances such as the hot water heater in the crawl space? The more use the Vapor Barrier gets the stronger you want the product to be.

We will go over all the options with you and help you decide which product is right for your home and your budget.

What is full encapsulation and is this right for my home?

This is a process in which the entire crawl space area is sealed. The foundation vents are blocked and the entire foundation wall is covered with rigid insulated Styrofoam board and is then taped at the seams. The foam board is an insulator with an R value of 13. The entire crawl space floor and foundation walls are covered with a polyethylene vapor barrier designed for the crawl space environment. The vapor barrier is taped at the seams using a UV resistant polyethylene tape so that no moisture can pass from the ground to your home.

The concept is based on something called “the stack effect.” This is a natural phenomenon of constant movement of air through the house. Essentially warm air rises and finds its way to escape into the upper areas of a house and then outside. As the warm air leaves the building, cool air rushes in through leaky windows, doors, and crawl space vents to replace it and repeat the cycle. The air in the crawl space gets sucked up into the living area bringing with it moisture, dust, mold spores and allergens. This effectively eliminates any possibility of meaningful cross ventilation and negates the possibility of allowing moist air to leave through the vents. We’ve included a link to more technical data on this subject. www.buildingscience.com  You can also vent a small amount of warm air into the crawl space to further protect from moisture. One advantage of insulating the foundation walls is you have eliminated the need for floor insulation.

There are still two schools of thought regarding this process. This system doesn’t fit every home. We’ll evaluate your home and help you decide the right solution for your crawl space. One word of caution here- if the crawl area is home to your hot water heater and/or furnace, these appliances need make up air for combustion and you must consult an HVAC professional before making a decision.

Doesn’t full encapsulation cost more?

Not necessarily. Remember you’ve eliminated the need for floor insulation and typically that is one of the major expenses in crawl space restoration process. We offer crawl space services that include everything from fully heated encapsulation to the more traditional installation of a basic vapor barrier on the floor. Whichever you choose, the result is always a clean crisp crawl space that eliminates odors and provides a cleaner environment for your home.

Call (253) 691-9239 or Contact Us for a free consultation about your crawlspace needs.