Here at EPB we love working in crawlspaces. We especially love sealing them up from the ground up.
Vapor Barrier
When you open a crawlspace hatch, do you smell a stench? Is it moist down there? A correctly installed vapor barrier can be a great solution to your problems.
On wet and dry crawlspace dirt we seal the earth from the crawlspace air with a 15 mil vapor barrier (a normal hefty bag is 1 to 3 mil). We do this in order to keep the moisture that comes from the ground from out of the crawlspace air and eventually the house. (even with dry dirt there is a lot of water coming through). We mechanically attach the vapor barrier to the foundation walls and seal them with water based sealant in order to keep the moist air out.
If there is a lot of bulk moisture in the crawlspace, such as standing water, we can dig and install a french drain system in order to keep the water out. After this is complete we would still install a vapor barrier in the crawlspace.
Crawlspace Sealing
After your crawlspace vapor barrier is complete we can now close off your crawlspace vents. Crawlspace vents are there in order to vent the moist air that comes from the dirt out of crawlspace. Without any moisture coming from the dirt, because of the vapor barrier, we are able to close these vents. After the crawlspace is sealed we install a humidity sensing data logger that will read and record the humidity of the air every ten minutes. This way we can verify the vapor barrier’s performance. If there is a concern about this method, we can install a fan controlled by a humidistat. This will turn the fan on if the humidity does get elevated.
What crawlspace sealing does is stop the house from breathing so much from through the floor of the house. By stopping this breathing of the house through the crawlspace we can reduce the heating and cooling loads by reducing the building leakage of the home. If we can place the ducts in a sealed crawl it is a huge bonus. This area is almost the same as the conditioned space above so it reduces the conductive losses from the ducts. It also increases the air quality of the house because it reduces the infiltration from the dirty crawlspace.
What better place to be than a mild temperature, clean vapor barriered crawlspace! Like I said, we love working in crawlspaces.
