I was also wondering about the effects of insulating the inside of the foundation in my crawlspace, using 2inch thick polystyrene. The underside of my floor is not insulated. And the crawlspace is a dirt floor. I was specifically told not to insulate the floor so that heat could seep into the crawlspace and keep the water pipes from freezing. (the waterpipes are insulated). But last week on a very cold day I went around back of the house and opened the door into the crawlspace. It was very warm in there. So I suspect I am loosing a lot of heat thru the foundation walls. Not to mention into the ground. Would insulating the concrete block foundation walls be worth the cost (ie: ROI > cost of lost heat). Thanks. Pooh Bear

By blocking/sealing the crawlspace you will definitely have some heat savings and increased comfort. With the cost being 1500 though it will probably take a while to recoup. If you sealed it yourself the materials wouldnt cost you anywhere near 1500 dollars more like 500 or much less. All you would do is cover/close the vents with 2 inch pink foamboard and place foamboard against the block walls. Seal them all with foam and then lay 6 mill poly sheeting on the floor (overlap 12 to 24 inches and tape them) and tape it to the foamboards on the wall. Its pretty easy if you have access to the crawl. Home depot sells the foamboard in 4X8 sheets for $25 and great stuff foam for 5 bucks a can. I dont know about the poly sheeting though but check it out.

yeah...Entergy is going to help you out! LOL! they do actually have a program in N.O. through Entergy using local energy raters. a little biased, but it is what it is. below is a copy & paste link to LSU AgCenter's study about insulating floors in homes with open crawlspaces. http://www.lsuagcenter.com/NR/rdonlyres/D33F711D-DC4B-4E4C-9ED6-A97DCE9DB026/79806/pub3187insulatingraisedfloorsHIGHRES.pdf I plan to insulate my floors with closed cell 3" everywhere...not average fill. once floor in bathroom is replaced and plumbing is finished. your biggest battle is going to be getting 3" everywhere, and not just averaged fill. plan to crawl under house before they leave. take a piece of wire with inches marked on it and a can of spray paint. have them come back and touch up low spots. knowing the foam companies you'll have to deal with, plan on double checking the work and not relying on their word that it is right. understand that closed cell is about R-7 per inch so 3" is R-21. actual R-values not quanitive values are what is important. best of luck.

I happen to have the NKBA book "Residential Construction" right here - am reading through it. Pg 67 addresses this. It says, "Kitchen and bath floors above crawl spaces should contain insulation to stem heat loss and a vapor barrier to keep moisture out. Insulation can go either between the floor joists or at the foundation wall. Insulating the floor itself allows the crawl space to be continuously ventilated (required by some local codes) but is harder to do. Also, any water pipes and heating ducts that run under or within the floor must be wrapped." We have an over-5-foot crawl space under our entire house and it's insulated just under the floor with the 6" batting type. Our vapor barrier (or at least what I *think* is our vapor barrier - we may have another one in the floor itself as talked about below) is huge sheaths of thick black plastic taped together with heavy duty tape - and the vapor barrier is sitting on the ground. We have not experienced the floor being cold at all - we have linoleum, wood, and carpet, and none are cold, even in the coldest weather. The paragraph goes on to say, "On the other hand, the foundation can be easily insulated on the inside or outside face. However, any vents in the wall must be closeable during the cold season. The location of the insulation also affects where the vapor-control barrier goes. If the floor joist cavities are insulated, the barrier should go between the insulation and room above, usually between the floor joists and subfloor. The best vapor barrier is a sheet of polyethylene at least 4 mils thick. The foil or Kraft paper facing on batt and blanket insulation is not a reliable vapor barrier. If you choose to insulate the foundations walls rather than the floor, the vapor barrier should go next to the inside face of the wall and extend completely over the soil below the crawl space. Another way to insulate the foundation is to apply rigid foam to the outside of the crawl space, but this is more easily done on new construction. An existing foundation will have to first be excavated down to the footing." HTH