Insulating Walls in a Hot Climate
Hi All-
Question regarding a remodel of a 1945 home in College Station, TX, climate zone 2A. I’ve been trying to do my research and reading everything I can on here but now am going in circles on how to proceed. We would like to investigate insulating the exterior walls since many of them have been opened up for wiring upgrades and window fixes (most of the newer windows appear to be leaking as no flashing was used when they were installed several years ago). We have completely removed the interior wood sheathing in 1 of the rooms to gain access – hence the last photo with it missing.
The home currently has (from the outside in) asbestos siding, asphalt felt in good shape, wood exterior sheathing and finally wood interior sheathing. After that, it’s a mix of 1/4″ drywall in some places and, wood paneling in others.
We had no idea how extensive the repairs were going to be when we started this project, but now are in the middle of it and have to keep going 🙂
So the question is – what do we do about the walls? We would like to insulate and reduce the air leaks going forward. I know many people in the area just cut a few of the interior sheathing boards and shove fiberglass batt insulation up there. Is this acceptable in our area and the most cost effective solution? Have also been reading on here about creating an air barrier between the siding and the insulation – although in the example I was reading about, the house lacked a WRB…I’m assuming the asphalt felt in our house provides for that. Also assuming no need for interior vapor barrier (unless required by code).
Do we still need to create that air barrier (rigid foam) between the asphalt felt in our house and whatever insulation we go with?
House is going to be a rental so not trying to make this our “forever” home. So what do you all think is best given our situation?
Thx in advance!
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Replies
Aggie class of 2016 here,
Fiberglass is perfectly fine as insulation but the bigger issue is you have no air sealing. Since you are not touching the asphalt WRB you won’t have a chance to tape the seams of your sheathing to make that your air barrier. You can opt to use spray foam to try to get a little more air tightness, but I’m not a fan of spray foam in general. You could just detail the drywall and do an air tight drywall approach but then any outlets in your exterior wall will need gaskets around them. For a rental it will probably be fine. Make sure the renters pay the utilities! Also consider blown-in fiberglass instead of paper-faced, which will give you a more compact fit but also reduce the food available for mold to grow on by not having the paper in the stud cavities.