Stick-built truss on platform-framed attic?
In reading a blog on venting roofs by Joe Lstiburek from a few years ago —
— the reader’s discussion briefly turned to a method of creating an air barrier in the ceiling by sheathing the ceiling joists with OSB or plywood, then building the roof on top of that platform. In comment #6, John Brooks posted a construction diagram of one such system (see attached).
My question is whether an on-site stick-built truss could be constructed using the ceiling joists as the bottom cord of the truss? How would the web members of the truss be attached through the plywood to the ceiling joist/bottom cord? And is there a practical way to include an energy heel on the truss? This would be for a 3:12 roof in a cold climate (6A), so I am shooting for R-60 using about 24″ of cellulose.
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