Can anybody tell me what the R value of a 10″ concrete basement wall that will be completely covered on the exterior from top of wall to footing with the R5 Tuff-n-Dri system? I am trying to get more detailed info to the HVAC contractor so that he can determine the size of the GSHP system for my 1500 sq ft finished basement.
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Got this by googling "R value concrete." Looks like you have about 3.7. I cannot think that the Tuff-N-Dri adds much.
Gene Davis, Davis Housewrights, Inc., Lake Placid, NY
The concrete is good for 0.08 /inch, the R-5 stuf is probably r5, the insude surface is 0.64 and the outside surface, below grade is 0.64. Unless you live north of Minneapolis, you only count heat loss in the first 3 feet below grade, totlat his up for about r=7.1. If you have to calculate the r-values of walls for your contractor, me thinks you're in for trouble.
I have seen R-values for concrete ranging from 0.08 to 0.12 R per inch, so a 10 inch wall will be somewhere between 0.8 and 1.2 R.
I understand that concrete itself has little R value but I thought I had read in the forums somewhere that when you completely insulate the foundation on the exterior, the thermal? mass of the wall increases the R value for calculating heat loss. The HVAC tech is very capable, I am the first one in our area (SE Conn) to throw this at him!!!