Article #1458 - REScheck Webcast Questions - Crawlspace
This article is based on questions asked during both the May 6, 2005
REScheck Training Webcast
and the July 28, 2005
as well as questions received through email following these events. The original language of the questions and answers has been modified to make them as generic as possible while retaining the applicable specific information.
For a house over a crawl space, what is entered for the area and how is insulation entered?
If the crawl space is vented to the outside, the crawl would be considered an unconditioned space and the floor above the crawl would be entered in RES check . The floor area is calculated in total square footage and the insulation R-value should be entered under the Cavity Insulation column.
For a conditioned crawl space, which is insulated and mechanically ventilated, the floor above the conditioned crawl space would not be entered in RES check . Instead, the crawl walls would be entered by calculating the height times the length of the crawl walls and entering the appropriate depth below grade, depth below outside grade, depth of insulation from the top of the crawl wall down to the footing, and insulation R-value.
The following link offers additional information on this subject:
Does the Energy Code Allow an Unvented Crawlspace?
Is there any difference between the outside insulation with foam and inside with foam in crawl space insulation?
The code does not dictate whether to insulate the outside or inside of a conditioned crawl space. However, for the outside there is language requiring the rigid board insulation be protected (ie, flashing or cementious scratch coat). RES check treats the insulating value of both installation the same for crawl spaces.
How do you enter cantilevered floor areas?
A cantilevered floor would be entered as a floor over outside air. This floor assembly can be chosen from the drop down list of assembly types under the floor component menu.
What is more efficient for crawlspace insulation, under the floor or on the walls?
If the crawlspace is vented to the outside, then the floor should be insulated to save energy. Fiberglass is one option, but it should be installed so that it maintains contact with the floor above.
Traditionally, crawlspaces have been vented to the outside. Now many building scientists think that the vents bring in more moisture than they remove in some locations, and it is better not to vent the crawlspace but to condition it. Code officials may be hesitant to accept this because they are often not familiar with this.
The following articles offer additional information:
-
To Vent or Not to Vent
- Does the Energy Code Allow an Unvented Crawlspace?
- Details for Mechanically Vented Crawlspaces - Code Notes