Best retrofit wall for eastern Washington
I live in southeastern WA state (5B). Summers are hot/dry, winters can get fairly cold and come with snow/rain. I’m looking at a house that has some mold issues, mostly from a poorly installed roof. It needs new roof, sheetrock, and siding (and I’m assuming sheathing all around). I would also assume it has 2×4 walls, and I would probably put in all new vinyl windows. So basically a total retrofit of the exterior.
My goals for this house are:
1. Insulation up to code (R-19) at minimum. This means that I need something in addition to the R-13 that will fit in the wall cavities, which has lead me to start looking at foamboards on the exterior, which lead me to the confusing world of vapor barriers.
2. Hold this property for at least 5 years and build it so the tenants or next owners won’t ever have an issue.
3. Do the renovations on a budget. Total wall area is about 1600 sq ft. My plan was to put R-13 in the wall cavities, and one layer of 1″ R-max R-6 foamboard on the exterior of the sheathing, getting me to the required R-19. This would cost me roughly $2000.
So after getting all kinds of conflicting information on the internet from seemingly legitimate sources, my head is swirling with confusion.
Do I need a house-wrap, and does it need to be a vapor barrier?
Do I need a vapor barrier between the sheetrock and the insulation/framing?
If it gets down to 10 deg F for a few weeks, is the R-6 enough to prevent condensation on the sheathing?
The foundation is not too far above ground, how to I keep pests and wet air from coming up behind the foamboard or getting behind the foamboard at the top?
I have done a lot of research on this topic, but still have no clue, any help is greatly appreciated!
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