Home>Discussions>INSULATION & HVAC>Insulating a west facing 2x4 stucco exterior bedroom wall in Arizona.
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Insulating a west facing 2x4 stucco exterior bedroom wall in Arizona.

We have lived in the house for ten years. It has two master suites. one upstairs, one downstairs. Our biggest problem is the heat we get from the west wall of the downstairs master. The house is built with 2x6 studs, except the west, two story wall, it's 2x4. We do not understand why, except maybe money savings.

We would like to know if it would be cost effective to take down the drywall and get it sprayed with wall tight foam, or rigid foam board? At a loss on what to do to cut the heat in that room.

If you need any other info to determine an answer to our problem, please don't hesitate to ask.

Thank you.

Re: Insulating a west facing 2x4 stucco exterior bedroom wall in Arizona.

I had a similar situation in one rental house, except it was a one story house.

I took down the drywall, there was NO insulation (house was built in the 50s and insulation was not code back then). So I insulated (fiberglass). Re-drywalled. Still hot.

I added attic insulation and I added an awning outside, across the room, to give me some shade, and...the room was cooler. Not by a lot, but just about 5 degrees cooler. Enough to help the a/c have some impact.

There was some cost involved, but I wasn't paying retail, and it was a tax write off for me. Your situation may be different, so you do your math, and do what's best for you.

Re: Insulating a west facing 2x4 stucco exterior bedroom wall in Arizona.

I can pretty much guarantee that it won't be cost effective, but it could be effective as far as making your house more comfortable.

Most of Arizona has a pretty wide temperature difference between day and night, so a wall with a high thermal mass is usually quite effective, storing heat during the day and releasing it at night, but at this point, that would be an expensive undertaking.

I would insulate it by taking down the existing drywall, put in fiberglass or rockwool batts and then covering the interior side of the wall with 4x8 foam panels that are 1" thick and foil faced on one side. The foil should face the insulation. Tape the seams to make the foam panels into a vapor barrier and then drywall over the foam. You lose an inch of space in the room, but it should be a lot more comfortable.

Paint the exterior side of the wall white or as light a color as you can get away with. If the exterior stucco looks like it might need some serious maintenance in the near future, you might consider tearing it out instead of the drywall, install the batts if there aren't any there already and then put the foam on the outside of the studs, but do not tape the seams. Then re-stucco.

One last thought that could be cheaper. Maybe you could install solar screens a few inches (or feet if you want) to shade the wall. They work on windows but there is no reason they wouldn't also work on a wall like yours.

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