Exterior construction/insulation for a new home
I am about to start building a 3000 sqft, 1 1/2 story home in zone 3A W/H (central Alabama).
The house will have a standing seam metal roof and a drilled pier foundation with open crawl space. Air handlers and ductwork will be above the first floor ceiling, on the back side of the second floor knee wall.
My current construction/insulation plans are:
– Roof: Metal roof / Ice & water shield membrane/ 7/16 OSB/ Closed cell SPF sprayed 5″ thick between 2 x 6 rafters
– Exterior Walls: Cement board siding / membrane / 1/2″ OSB / Closed cell SPF sprayed 3 1/2″ thick between 2 x 4 studs on 16″ centers / 1/2″ gypsum board
– Bottom floor: Hardwood floor / 3/4″ T&G Advantech OSB / Closed cell spray foam sprayed 4″ thick between 2 x 12 joists
The builders I have talked with have concerns that the enclosure will be too air tight from the CC SPF. I intend to address this with a ventilation duct to outside air tied into the HVAC system. They are also concerned about trapped moisture causing the OSB and other wood to rot.
Would you recommend any changes to my exterior construction/insulation plans?
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