Is R-1 fan-fold insulation cost-effective as vinyl siding underlayment?
I am installing vinyl siding on a home in Pittsburgh PA as part of a HUD financed project. As such, HUD has supplied the specs. The requirement is for R1 fanfold followed by Tyvec. I think that the principal function of fan fold has traditionally, pre-house wrap, been to limit air infiltration (not provide R value), a function that is in this case served, redundantly, by the by the Tyvec.
There is almost no wall insulation and no plans to install any soon but there is adequate attic floor insulation.
I think that the money for the fan fold (.50/sq.ft +/- for 3500 sq.ft.) could be better spent.
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