Sealed and Conditioned Crawlspaces
Most homes built over the last 30 years were built with what is called a vented crawl space. The wooden framing of the home sits on a concrete block foundation which lifts the home up 2+ feet above ground over the dirt soils below. It was then decided that if you placed vents in the block foundation wall to allow air flow through the crawl space, it would help to minimize the moisture build up from the damp soils below. Finally, the sub-floor would then be insulated with fiberglass batt insulation.
Unfortunately, fiberglass insulation does a poor job stopping air infiltration, not to mention that the installation of the fiberglass product to the floor joist is a far from perfect fit. This easily allows the cold outside air to infiltrate your floor in the winter, and the hot humid outside air to infiltrate your floor in the summer.
As if that is not enough, most homes have a maze of heating and cooling air duct work located throughout the crawl space. All this duct work is most commonly carrying air of the opposite temperature from the current outside air environment, which creates inefficiencies in the effectiveness of the heating and cooling system, not to mention duct work sweating (moisture buildup). (The ducts carry cold air through hot duct work in summer and warm air through cold duct work in the winter). This combination of air leakage and creates the largest energy inefficiencies of your homes heating and cooling system, and cost you money.
A Sealed and Conditioned Crawl Space is the best solution to reduce air infiltration. A sealed crawl space is achieved when you eliminate all vents in the crawl space which stops all outside air infiltration to the crawl space. After you eliminate the venting of the crawl space you now need to seal the crawl space floor from the crawl space area. This seal normal consists of a moisture/vapor barrier installed on the crawl space floor and sealed to the crawl space wall to keep the moisture from the soils down below the barrier. Finally, conditioning take place by adding current heated or cooled air from the heating/cooling system directly into the crawl space. This keeps the temperature of the crawl space very consistent and close to the interior tempter of the home, regardless of the season. This helps reduce moisture build up on the duct work, reducing humidity levels, and allow the heating and cooling system to supply air flow through the duct work in the same temperature it will be received in the interior of the home.
You now have stopped air infiltration, reduced moisture and humidity in the crawl space, and helped your heating and cooling system more effectively. All in all you have saved your self money as well as possible future headaches.
How We Create A Sealed Crawl Space
First, a 15 mil vapor barrier will be laid on the crawl space floor. The vapor barrier will extend between 6 to 12 inches up the crawl space wall. The vapor barrier will then be ramset with concrete nails into the concrete block crawl space wall. The crawl space walls will then be sprayed with Demilec Sealection 500 approximately 3 inches up from the crawl space floor area to the top of the band board at an R-Value equal to R-10. Midway up the crawl space wall a 2 inch area will be left unsprayed to be used as a reveal for termite inspection. All areas where the vapor barrier overlaps and all piers will be tape sealed. Lastly, a baffled air register will be installed to supply conditioned air to the crawl space (50 cfm per 1000 square foot of crawl space).