Replies

1. 
   DavidThomas | Sep 16, 2002 05:51am | #1

   The idea is that the crawlspace is insulated (done in Alaska too, sometimes). I'd check the temperature down there to see how much differential there is (i.e. would insulation save you much heat loss). Than act on that info next year.

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska
2. 
   MartinHolladay | Sep 16, 2002 03:36pm | #2

   Kerfd,

   It sounds like the insulation is in the right place.  I'm not sure how they do it in Alaska, but here in Vermont we install crawlspace insulation on the crawlspace walls.  If the walls were uninsulated, and the wood floor joists were insulated instead, the pipes in the crawlspace would freeze.  A properly built sealed crawlspace with poly on the floor and insulated walls should have fewer moisture problems than a ventilated crawlspace.  And since you don't want frozen pipes, I don't think you have a choice.

1. 
   kerfd | Sep 17, 2002 03:23pm | #3

   Hey, thanks for the info. But maybe I should rephrase my question to ask if you think it would do any good to insulate the floor in addition to the crawl space walls?  My idea is to try to minimize heat loss through the floor into the crawl.  I would think that the crawl would stay near the year round temperature of the ground (or within a few degrees) which is near 40-50f.  I wouldn't want to go to the expense or the trouble (itch, itch) to insulate the TGI's if it doesnt pay me bach in a reasonable energy gain. 

1. 
   DavidThomas | Sep 17, 2002 04:16pm | #4

   The floor is the last place to insulate (after ceilings and walls) return-on-investment-wise. Also consider that you need some heat getting down there to keep the pipes from freezing. At least in my climate you would. I'd see the biggest reason to do it, if at all, one of comfort. If you're in bare feet a lot and the floor seems cold, then insulating it would help. Otherwise, I'd look for bigger fish to fry.

   David Thomas   Overlooking Cook Inlet in Kenai, Alaska

1. 
   kerfd | Sep 17, 2002 08:46pm | #8

   Great responses and thanks for all your help.  I think David's hit the proverbial nail on the head and I'll monitor my bare feet (and maybe my propane bill) for any discomfort this winter.  The 2" of pink foam and the heavy vinyl vapor barrier that is already installed should provide protection for my water pipes and guard against the moister that comes with a crawl space. 

2. 
   booch | Sep 17, 2002 04:37pm | #5

   Consider the local farming (short term) approach to insulating the crawlspace. Surround the foundation with hay bales (the old fashioned little square ones). That'll pass in the UP. At least if you are out in the country a bit.

   Consider radon as well. You need to ventilate the crawlspace to keep that at bay as well as keep the moisture level down to prevent excessive mold growth.

   Cheap, easy and permanent solution is getting some foam board (2") and dig down next to the exterior of the foundation before the frost hits. Apply it to the house foundation up and covering the rim joist. In your climate there is no worry about termites. A little sill cap all around the house and it'll look acceptable, like an oversized foundation. There are spread on stucco coverings or you can use the roll form aluminum to provide a weather resistant covering to cover up the oh so attractive pink or grey foam board.

   Final thought. If you decide you are going to insulate the floor. The vapor barrier goes next to the living space not under the floor joist. (and you thought it would be easy) I guess you could heat tape & insulate the pipes. If you do that you make sure you can crawl under there to thaw it out in January.

1. 
   PenobscotMan | Sep 17, 2002 07:00pm | #7

   What about insulating the floor of a house that is perched on posts (concrete and block piers, etc.)rather than a continuous foundation? I note your recommendation that the vapor barrier should be facing the living area (i.e. up). Most folks with houses on posts where we live part of the year (coastal Maine) staple fibreglass insulation between the floor joists, foil down, and then support the whole business with chicken wire or strapping (furring strips). Any thoughts on this? Also, does anyone have any good ideas for some non-ugly way of reducing windflow under a house on posts?

1. 
   booch | Sep 17, 2002 11:17pm | #9

   Vapor barrier has to do with condensation.

   If the house is colder than the outside (say Florida or S. California.) because you have the airconditioning on all of the time,then you put the vapor barrier tword the humid or hot side.

   If the house is warmer than the outside weather (say Wisconsin or Maine) cause you have the heater on most of the time, then you put the vapor barrier tword the inside of the house.

   The hotter area holds more moisture in the air and the cooler area is the location where it condenses.

   Now the Maine story may be different due to the Nor'Easters and that stuff. The locals generally have a good take on a situation. But in this case it looks like the application is using the insulation like a raincoat to keep the insulation dry. I'd bet if you pierced that foil it would be loaded with mold on the backside of the foil.

   If I was there I'd probably spray the underside of the structure with urethane foam insulation after new construction. I'm just guessing at that. You could find many people to do that now. I suppose you'd have to cover it? Depends on the job I'd expect.

   As for reducing windflow. Plants around the foundation are a good start. Second try a fence or lattice of some sort. If you are on a budget, you can always get those blue tarps from the Home Improvement Center. As cheap as those blue tarps are you could wrap the town of Bangor for a little over $22.00.

   Edited 9/17/2002 4:56:39 PM ET by Booch

3. 
   Nails | Sep 17, 2002 06:25pm | #6

   From central Illinois temp to -20 have found insulating from inside rim joist to bottom of sub-floor in about 30in around perimeter of house most inexpensive way with greatest return. Watch for air infiltration, top of foundation , sill sealer even behind insulation on block wall that was previously installed.