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Fantech Kits |
 These handy kits include fans, mounting brackets, Y adapters, collars, clamps, and lights. See individual kits for contents. Great quality and value! |
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AirScape Fans |
 Reduce indoor air temperature by pushing the hot air out of the house through the attic and replace it with cooler outside air. Quiet and reliable. |
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How To's: Our Do-It-Yourself Help Section
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Stego Wrap - Lining Crawl Spaces.
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The following is an experpt from an article published by Stego Industries. For more information, plese see
their website at www.stegoindustries.com.
Crawl Spaces - A New Perspective. Written by Paul Miller.
The use of vented crawlspaces in residential construction continues to be a popular mode of construction. However, little attention has
been paid to the potential problems associated with this building practice. Throughout the Southeast many crawlspaces develop severe mold
and mildew problems. This can create health risks when the spores are able to enter the building envelope. In dryer regions, crawlspaces
allow cold air to come in contact with the building envelope during the winter months creating increased energy costs. In addition, during
the summer months moist, cold air condenses quickly when it comes in contact with cold surfaces such as rim joints.
The use of vented crawl spaces derives from pre-World War II theories of construction. Based on these theories the Residential Building Code
calls for ventilated crawl spaces, allowing very few exceptions. (IRC Section R408.1) Proponents of ventilation argue that vents allow
exterior air to pass through crawl spaces and evaporate moisture. However, modern research shows that vented crawl spaces actually produce
the opposite affects. In humid regions of the country external air is often more humid than the crawl space, in affect allowing far more
moisture to enter the space than would exist in a space not vented. In addition, vented cralw spaces are a liability in dryer climates.
During the winter months heated air within the building envelope rises and escapes into the upper areas of the house creating a pressure cycle
that literally sucks cold air up from the crawl space. This cycle not only increases energy costs but the cold air brings along with it the
added danger of dust, mold spores, and moisture from beneath the house.
For these reasons and others including cost of construction, many experts have been discussing alternative options for vented crawlspaces.
The most common choice is to close the crawl space. In practice this means treating the crawl space as a sort of miniature basement.
The US Department of Energy states,
If you have or will have an unventilated crawl space, then your best approach is to seal and insulate the foundation walls rather than the subfloor.
The advantages of insulating the crawl space are as follows:
1. You can avoid the problems associated with ventilating a crawl space.
2. Less insulation is required (around 400 square feet for a 1,000-square-foot crawl space with 3-foot walls.)
3. Piping and ductwork are within the conditioned volume of the house so they don't require insulation for energy efficiency or protection against freezing.
4. Air sealing between the house and the crawl space is less critical.
The US Department of Energy and the authors of "To Vent Or Not To Vent" agree that a key to sucessfully designing an unvented crawl space
involves sealing the floor from moisture. Depending on your water table this may involve several solutions. In the case of a high water
table it might be best to consider the use of waterproofing and a thin slab of concrete. Generally this is not necessary and the use of a
plastic barrier will suffice. Many older articles simply recommend the use of 6 mil poly, however as Crosbie and Zoeller write, "The typical
6 mil polyethylene easily can be ripped by crawling on it, and the edges and seams are difficult to seal to the walls." For this reason a better
choice would be the use of a polyolefin plastic barrier with an extremely low permeance. Most experts agree that the permeance level should be as
close to 0.01 perms as possible. A low as possible thus keeping the humidity low and reducing the chances for mold and mildew.
As always, if you would like to ask more questions about this or other technical topics give us a call at 877-711-4822 - 8-5 PST.
Live people for technical and sales support - an Internet first!
Disclaimer:
Advice and information given through our representatives is checked for usability and
conformance with most codes. You as the user, however, have the responsibility for
verifying conformance with local codes and standards and ensuring a safe installation.
Although HVACQuick.com may employ and use professionals, their advice is not meant as
substitute for professional engineering services. It is the customer's responsibility
to hire and retain suitable engineering and architectural professionals as required.
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