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Installing a Your Crawlspace Vapor Barrier System – Part 1

Whether doing a fully sealed crawlspace encapsulation or only adding a high quality and permanent vapor barrier, the best place to start is with a little basic research. Here are a few links that will get you started. The first two are from Advanced Energy, a nonprofit research organization who did much of the ground breaking work on crawlspace encapsulation (sealing). The next two are from the Environmental Protection Agency (EPA) and the Department of Energy’s (DOE’s) Oak Ridge National Laboratory, also sources of good information. You might also want to check-out your state’s energy office for some tips specific to your region.

When considering crawlspace vapor barriers, all the experts have a number of recommendations in common. Many of the recommendations are just common sense. Before you start, be sure that ground water is diverted away from the foundation and that the crawlspace has been cleared of any debris that could puncture the vapor barrier. Many of the common recommendations also deal with installer and homeowner health and safety - not exactly riveting reading, but important information never the less.

Now on to the actual installation. All the experts also require the vapor barrier extend up the wall and be attached and sealed to the foundation wall. If doing an encapsulation (including the crawlspace in the building envelope and making it conditioned space) the experts agree that the vapor barrier should extend up the wall, stopping four to six inches below the sill plate to allow for an unobstructed pest control inspection area. If only adding a quality vapor barrier and not sealing the crawlspace, the experts recommend extending the vapor barrier up the wall, six to twelve inches above outside grade. In either case, the vapor barrier needs to be permanently attached and sealed to the foundation wall.

This is where the recommendations become vague. The experts do not agree on a method of attaching and sealing the vapor barrier to the foundation wall. I suppose they’re leaving those decisions up to the installers. And if you ask five different installers, you’ll probably get at least six different answers.

Some crawlspace contractors use a combination of black powder guns, hammer drills and Tapcon screws, masonry nails, pressure treated furring strips, special tapes, mastics, and caulks. The various techniques have advantages and disadvantages and some are more effective than others. They all have a few things in common. They require special tools, they are sometimes difficult and awkward in a confined crawlspace, they are time-consuming adding hours to an install, they can damage the foundation wall, and they are ineffective on uneven foundation walls or fieldstone foundations.

The Your Crawlspace system requires no mechanical fasteners, caulks, or mastics. The Your Crawlspace Crawl Curtain was developed and patented to provide a permanent attachment and seal in one simple step – using no mechanical fasteners. It installs on any crawlspace foundation including poured concrete, concrete block, brick, and even fieldstone. The Crawl Curtain easily attaches and seals uneven foundation walls contouring around inside and outside corners. Using the recommended Your Crawlspace polyurethane construction adhesive, it even attaches and seals a water saturated foundation wall. The Crawl Curtain vapor barrier installs in a fraction of the time as conventional vapor barriers, saving a crawlspace contractor many man hours. And time saved is money earned.

In addition to sealing the walls, it’s also necessary to seal any foundation piers. While it’s not necessary to seal the piers themselves, it is necessary to seal the seal the floor vapor barrier around the piers. Your Crawlspace tried several techniques and found that wrapping and sealing the piers with wall material provides a good surface to seal the floor material around the piers.

The walls and piers are sealed with a quality vapor barrier. My next post will deal with installing the floor, sealing the seams, and buttoning up the job.

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