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  1. #1

    Default insulating crawl space

    Have a room addition 16x18' has 2 heating ducts and cold air return . Has 2 outside vents and a heating duct inside crawl space, floor is covered in concrete not smooth but no soil exposed. The crawl space has access to main basement through a basement window and crawl space is about 30" high. The rooms exterior walls were insulated when room was built. We added insulation in ceiling (attic) and insulation company insulated under the floor and wrapped the heating ducts and pipes and closed off the heating duct into crawl.... It is still cold in room and must use portable heaters in the winter. Should we open the basement window and insulated the exterior walls of crawl space and open the heating vent into crawl space and seal outside vents?..... If we do this should we remove the insulation under the floor or leave it. Also should more heating vents be added to the room? Confused and cold in northeast ohio.

  2. #2
    Join Date
    Aug 2007
    Location
    The Great White North
    Posts
    4,045

    Default Re: insulating crawl space

    Frankly .... the mention there are open vents to the outside and there was a functioning heat duct in that space has me shaking my head in disbelief.

    If the walls , floor and attic of this addition were well and properly insulated along with proper air sealing will be the first major step.

    The way I see things ....... The vents to the outside should be completely sealed closed.
    The 3 perimeter walls of the crawl space should be well and properly insulated and sealed. The insulation under the floor can remain .

    Since the floor of this crawl space is covered with concrete you should be able to include this area as conditioned space by opening the heating duct and leaving the access window open to the existing basement. If leaving this open is an eyesore then have a louvered door or grate covering the opening allowing air circulation to this area.

    I'm guessing the furnace is located in the basement with the heat and return ducts located at floor level in the addition ..... where they should be.

    The questions that come to mind are ..... was the furnace size and the cubic feet per minute ( CFM ) delivery considered with the 16x28 addition ? Also ... the size , run and placement of the supply and return ducts?

    This is one area I suspect that might be a contributor to the issues.

    If there isn't enough air being delivered to this room because of undersized or very long run supply ducts or the furnace isn't producing enough this would certainly cause a cold room. In other words .... if the air coming out of the heat vents is cool and/or low volume would be an indication of this and wouldn't heat the room very well.

    You might have a heating contractor evaluate your heating system .... they can measure the CFM and temperatures being delivered to this room.

    Hopefully this makes sense and helps.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  3. #3
    Join Date
    May 2008
    Location
    Pacific Northwet
    Posts
    1,602

    Default Re: insulating crawl space

    I agree with canuk about treating the crawlspace as "conditioned space." Here in the Pacific NW, some builders are experimenting with "green technology" -- one of these is to treat the crawlspace as conditioned space.

    Basically, the floor is left uninsulated. Foam insulation panels are placed in the crawlspace area around the perimeter of the foundation; the entire crawlspace is then floored in concrete. There are no crawlspace vents, and the floor is left uninsulated. In other words, think of it as a 2 foot-high basement rather than a crawlspace. Initial studies have shown that this method may reduce energy costs. (To prevent buildup of radon and other soil gases, drain rock is placed under the concrete and ventilation pipes to the exterior are provided.)

    In your case, it sounds like this might've been the intention, but perhaps the inspector required the builder put foundation vents in because "the code requires it." Well, for that type of construction the code doesn't require it (hey, it's a 2' high basement not a crawlspace), the inspector just misinterpreted it and besides "that's the way it's always been done." Seal up the foundation vents as tight as you can. Open up the furnace vents and treat the space as another room. I wouldn't worry about removing the insulation that's been placed under the floor; it isn't hurting anything.

    I'll add that this type of construction must be a joy to work with when you have to work in the crawlspace! I've never been so lucky.

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