Planning a new double-stud house — what should I change?
My wife and I are planning a 2,100-square-foot house in Massachusetts. Here's the plan: a south-facing wall with glazing equal to 13% of the 1st floor area. A 5" radiant slab on grade with 4' frost wall on footings insulated with 4" of xps underneath with a stepped foundation top to minimize thermal bridging.
We were planning a 10 1/2" cavity double-stud wall with dense-pack damp-spray cellulose and lots of air sealing. Huber Zip System exterior sheathing with strapping and vertical pine siding sealed on all sides for a rainscreen wall.
The ceiling on the second floor would be mostly vaulted with 2x12 rafters with dense-packed cellulose. Our plan was to put 2" of isocyanurate on the outside of the sheathing and do a cold roof of exposed fastener metal roofing.
For systems we would have all radiant upstairs and down, heated by a Polaris propane water heater. Hot water would be tankless on-demand propane. We would install an HRV system with intakes in the upstairs and downstairs baths as well as the kitchen and supply lines in the bedrooms and living room.
We are also toying with doing photovoltaics due to the availability of Solar Renewable Energy Credits here, and also a solar hot water pre-heat system, in which case we would eliminate the tankless and use a heat exchanger with the Polaris.
I don't really know what I'm doing so any and all advice would be appreciated before we start and I royally screw this up!
Thanks in advance. - Noah Kaput
Posted Thu, 09/15/2011 - 11:30
Edited Thu, 09/15/2011 - 12:09
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Since drywall has a permeance of 0.02 liter/sec - m at 75 PA is ever possible to have sheathing dry to the interior of the home?