Anyone else in a Mixed humid climate(like Dallas) used sprayfoam in the stud cavity with rigid foam outside of the studs? If so, did you estimate what your energy savings would be with the rigid foam vs without? I will eventually turn my plans over to an energy rater…just wondering if anyone else has already “been there”
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I built just south of Dallas. I cannot answer your question exactly, but I can give testimony to spray in foam insulation for this area. The highest electric bill for AC I have paid was $260.00. My base usage is about $110. One thing I did in addition to the spray foam is foil/kraft on the outside instead of tyvek type house wrap. The foil reflects the heat away from the house. One note, I did this behind brick and stone. I have read if it is directly covered as in siding it will not help much. Hope this helps.
Burbo,
I am going with the open cell sprayfoam for sure. Just trying to decide about the xps or not. I am also considering using wood furring strips behind my hardi siding. I wonder if the 3/4" air space would make the radiant barrrier type housewrap worth using?
I would like to hear more about other strategems you used to deal with the North Texas conditions.
Thanks, John Brooks
I think that it is very difficult to justify the cost of spraying foam in the walls in the North Texas area.
Some quick math shows that for a 1,000 sq. ft. of wall at R14 with 105 degrees outside, 75 degrees inside, a 13 SEER air conditioner, and $.13 per kilowatt - the electiricty to run the A/C unit is just under 2 cents per hour.
More important is sealing any air leaks, eliminating or shading west and east facing windows, and most important, keeping the duct work out of the attic.
Paul,
I agree with your priorities and yes the spray foam is pricey. I would like to talk with you if you have time. I will send you my contact info by private post.
John
Tim, I would like your comments. Is this r value argument valid or too simple? I know the foam is expensive...but it sure simplifies air sealing. Back to my original question....How can I evaluate if the xps is worth the trouble?
Paul, How is the framing going on your house. Has the REFORM wall caused any challenges for your framers?
The framers and I are adapting as we go. A pier and beam house adds new twists to the implementation.For example - I am following behind the crew doing the sheathing, and putting up the peel and stick house wrap. To avoid the time lost for a sheathing inspection in that process, the framers are adding cut in bracing to the structure. The sheathing crew works faster than I do, so I work longer hours to keep up. It is a very busy time.
Paul, I know your busy..hope your taking photos and have time to post some when you get caught up. I am going to start studying PERSIST and see if it is the same or similar to REFORM.
Usa the ADVANCED SEARCH for PERSIST system. That has been discussed here several times by Ray (Moore?).
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thanks, Bill ...it looks like I have some reading to do. I have been looking at posts about the REFORM wall and Ray Moore...but I had not come across the PERSIST term. I am pleased to see the other Ray Moore screen name... that may open some other windows. I like what Ray is talking about with REFORM. I just don't know if I am brave enough to "go there" yet.