Insulation in the right location? Air-seal sufficient?
I’ve been lurking on the forum for quite sometime and have spent hours and hours reading posts and comments.
I’m located in Marine 4C in Washington State and we get about 20 inches of rain a year.
We are building a 2000 sqft 2 story and want to have it well insulated.
Slab on grade with 4 inches of compacted crushed rock, 6 mil poly vapor barrier, 2 inches of R10 pink rigid foam cut at 45* at the footing and going down. Then another 2 inches outside the footing going into the ground 24 inches
Walls will be advance framed 2×6 with (from the inside) 1/2 sheetrock, R23 roxul or blown cellulose, taped OSB, 4 inches of taped polyiso (1 piece, not stacked), WRB (probably Tyvek), vertical 1x4s for a rainscreen, and hardiplank or panel for cladding. Windows and doors will be “Outies”.
1st floor ceiling will be 5/8 sheetrock with roxul SnS to keep the noise transition down a bit.
2nd floor ceiling will be 5/8 sheetrock, 4 inches of taped polyiso (again, not stacked), healed trusses 24″ on center, and R49 blown in cellulose on top.
Attic access will be through a barn door in the gable end and no holes in the ceiling for lights or fans upstairs.
Is my WRB between the foam and 1×4 rain screen enough? Should I put another layer between the foam and the OSB?
Should I put 1x4s going perpendicular to the trusses upstairs between the sheetrock and the 4 inch polyiso so I dont need such long sheetrock screws?
Do I need to worry about condensation between the polyiso and the bottom side of the trusses?
Do I need to worry about condensation in my wall cavity?
Since I am taping the foam and the osb (Smooth side out) do i still need to seal my framing cavities with ECOSEAL or this thing? http://www.spraysealantsgun.com/
Does this look like a decent design that should be practical and last a good many years?
Thank you for any and all input. This site has been incredible and its great to be with some like-minded people!
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