I'm thinking about insulating the floor above my crawl space, has anyone done that? I know there's as much benefit as well insulated walls and attic (which I already have insulated), but it would be nice not to have my new tile floors being cold in the winter.
My only concern is freezing pipes under the house - any problems with that after insulating the floor? I'm in the mountains of Southern California, where the coldest winter temperatures are usually around 20 degrees or so, sometimes in the teens, single digits if record breaking.
I know insulating crawl space walls instead of the floor can be done, but I believe that is not an option for me as my crawl space is vented and I need combustion air for my floor furnace.
Hi Brian, just some quick thoughts for you.
Basements and crawl spaces have the two options you mentioned. Insulate the floor or the walls. Since a crawl space usually has a dirt floor, if you insulate the walls you will need to add a moisture barrier over the dirt, sealed to the walls. That can sometimes be a project, but a dirt floor can put out gallons of water per day. You can test it by placing a six foot square of plastic over an area and go back the next day and lift it up. If it is wet underneath then the soil is wet. Where I live it would be dripping wet in an hour. Even if dry, the moisture barrier is recommended.
For the other option, insulating the floor, you are isolating the house from the crawl space and would have to protect any pipes or other appliances like the furnace, water heaters, pumps or others. Your temperatures aren't too bad, we call that spring . Be careful with heat tapes if you go that route. I wouldn't. Some furnaces can be adapted for an outside combustion air supply. I'm not up on furnaces so you will have to check that out. If you do insulate the floor, don't cover the bottom of the floor with plastic. A moisture barrier is supposed to be on the warm side of the insulation. On the inside, in cold country, on the outside in warm country. When you deal with heating and air conditioning, you don't use plastic. Use a house wrap.
Now, before you close anything up, air seal everywhere you can. Holes for electrical, plumbing and such. Anywhere air can leak into or out of the house. Once insulated you don't want to have to go back after leaks. Use the approved foam or caulking for small holes and sheet metal for large areas. Unfortunately, fiberglass does not stop air flow.
If you can provide some more details I can try to be more definite on a recommendation. Also, describe that furnace as I'm not an HVAC guy.
Bud
Rather than insulating and dirt-vented crawl space, I'd recomend you to encapsulate and condition the crawl space itself.
You might not even need to apply insulation to the floor at all if you do that, because the crawl space will become part of the house envelope.
And if you want to insulate, you can do it knowing that the insulation and floor joists will be protected from moisture and mold.
Not to mention that your whole house will be more energy efficient. The crawl space will no longer be humid or blow that humid air into the house. Dry air costs less to heat and cool.
And if you have ducts running in the crawl space, you will eliminate current energy losses which can be as high as 50% in ducts running in cold humid dirt crawl spaces.
Here's a site with great information:
Crawl Space Repair Guide by Dirt Crawl Spaces
Whatever method you choose to insulate, the soil in crawl space should be covered with at least an 8 mil plastic vapor retarder, overlapped, taped, and up foundation walls and attached there with silicone caulk to retard moisture emissions.
Tags: insulating, floor, above, crawl, space, crawl space, crawl space, crawl space will, insulating floor, moisture barrier, space will, crawl spaces, dirt floor, ducts running
