Sealing crawlspace worth the investment?

Discussion in 'General Discussions' started by Carl, Mar 17, 2009.

  1. Carl

    Carl New Member

    Is sealing crawlspace worth the investment in an existing home prior to designing and installing a geo system? Any other improvements besides insulation and heat/cool transfer I should consider?
  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    Your numbers will tell you this

    It depends on your energy loss through that area which of course depends on the sq.ft, your location, building material, and so forth. A room x room heat loss/gain calculation will give you the answers you want.
  3. arkieoscar

    arkieoscar Member

    It can have benefits, especially if the floor is not insulated. A vapor barrier is the best investment. It can keep the space dry and reduce mold, etc. in the crawl space. Insulating the walls can cause problems for termite inspections but leaving a 6" gap at the bottom may cure that. As part of an energy plan, it's certainly worth it in most cases. I had to have vents installed in '95 per building code but sealed them up as soon as I could and treat the space just like a basement and it's been good for me.
  4. Carl

    Carl New Member

    Thanks alot. After you sealed vents did you attach vapor barrier to sill plate? Also, I have been advised it is better if a heat duct puts air in one end of crawl and a return is cut into opposite end to treat the crawl space. What are your findings?
  5. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Heat goes to cold

    The exact number has slipped out of my brain as gray hair, but I think something near 30% of a buildings heat loss is through the floor. If anyone has a real number please correct my error.

    So do the math, $1,000 winter heating bill times 30% is $300. One can buy a bunch of insulation for $300. Then add the tax credit and it gets better.
  6. arkieoscar

    arkieoscar Member

    I glued 1" foam to the sill plate, between the joists and down the (block) walls. No vapor barrier although the closed cell foam will stop most. I did try to get the fit tight but didn't caulk. I wouldn't consider heating or cooling it unless I had something down there that required it. My heat pump is down there and likes it just fine the way it is.
  7. ncgeo

    ncgeo Member

    Sealing a crawl space has variable benefits depending on the climate, but is certainly not a ncessity for geo. Here in the Southeast sealed crawls are starting to catch on, mainly to reduce mold issues from the humid climate. In effect they become mini plastic-lined conditioned basements. Makes sense here but probably not so much in a desert climate. Also I understand some jurisdictions require venting a crawl, probably because that's the way it was always done.

    I have geo with an uninsulated, unconditioned basement so in-effect have an unsealed high crawl with a concrete floor. Underneath first floor is insulated. I have no issues, but it is noticeably humid in the basement over the summer.
  8. Rancher

    Rancher New Member

    Desert climates tend to be slab on grade construction, no basements or crawl space.


Share This Page