Wall System for Climate Zone 6B: Off-grid, wildfire and earthquake prone with dramatic temperature fluctuations
My wife and I are in the planning/design stages for a passive solar, solar-powered single family home of approximately 1,600 sq. ft., at an elevation of 6,500′ within a national forest in southwest Montana (Climate Zone 6B). The site is relatively remote and off-grid–nearest electrical hook-up is 8 miles distant. The area lies in a seismic zone and owing to dry summertime conditions, experiences periodic wildfire activity, the risk of which is made worse by the expansive area(s) covered by standing and fallen beetle-killed lodgepole pine trees. Local temperatures can range between 100+ degrees in the summer to -40 degrees in the winter, with annual heating days of approximately 8,500.
Because of the wide temperature variations, risk of fire, remoteness of the site, and stand-alone nature of the structure, we’re attempting to build in a manner that will minimize wintertime heating requirements (primarily), but also air leakage and thermal bridging, aiming for a whole wall R-value of 40-45, and sheathed in fireproof/resistant material (e.g. cementious board and batten siding).
What we are contemplating is something of a hybrid Klingenberg wall system featuring a 2″x4″ balloon-framed inner load-bearing structure clad in drywall, an Intello-Plus air/vapor barrier, and sheathed–for air barrier purposes–Zip system panels with taped seams. Secured to this would be Larsen trusses which in turn, be sheathed with Densglas (or comparable) panels (also taped), over which would be a wood lattice (drainage plane), and finally, cementious siding. The type of insulation we’re considering is either blown cellulose or rock wool battens.
My question, then, is two-fold: (1) Is this overkill in terms of complexity, price, and safety; and (2) will such a system (or another) be effective in preventing/retarding in-wall condensation while providing needed fire-proofing/resistance?
Many thanks in advance for your response(s).