Quote:
Originally Posted by dablack
...I was thinking going three layers over the whole house, but I could go four layers on the roof and then two layers on the house.
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This sounds like a really good idea. I don't know that the insulation codes are in TX, but in OR the current insulation requirements are:
- Roof - R49
- Walls - R20
- Floor - R30
I know that the Oregon Department of Energy does really good work. I have been personal friends with a couple of people employed there, and they are very smart and very interested in moving the state forward in anticipation of eventual global energy decline.
If you are confidant that the TX energy department is trustworthy, you might check them.
But I mention this stuff to give you an idea of the ratio of insulation distribution. So, I would say that your idea of more in the roof and less on the walls looks good.
I'm sure that you are well aware of the need for vent channels under the roof layer.
Another idea that you may not have considered is aluminum shingles. I have them on my house and they are a total miracle. They don't wear out... that's right, they don't wear out.
I made the mistake of going with green painted aluminum, I really should have gone with unpainted aluminum, my house would have been much cooler in the summer.
The photo above is one that I took about three minutes ago. The roof in the photo is on a house that is right across the street from mine. The roof you see in the photo is unpainted aluminum, and has been there since the early 1950's. That's about 60 years ago. The roof looks absolutely new. No failures, no leaks, no blown-off shingles (they all interlock together).
Aluminum roofs are more expensive, but I did the calculations that I could have a crew do my roof in comp, or I could do my roof in aluminum myself (it took a really long time) for the same price. So, now I'm good for as long as I am in this house. Roof issues are completely over.
Quote:
Originally Posted by dablack
I do plan to come back and do spray foam under the roof deck in a couple of years and that is why I thought it would be good to get three layers on the walls.
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Not enough info to make a decision on this...
Best,
-AC