Wall Assembly R-Value

The whole-assembly R-value of a framed wall by the parallel-path method, where the studs short-circuit the cavity insulation -- the wall performs below its center-of-cavity R. Reports both.

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Formula and source

U_assembly = framing factor x 1/R_framing-path + (1 - factor) x 1/R_cavity-path; R = 1/U; framing path adds stud depth x 1.25 R/in.

ASHRAE Handbook of Fundamentals parallel-path (isothermal-planes) method (by name).

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