how much difference in price and quality between R19 and R20 per square feet ?? 9 m' \7 Z6 _; m ! B( v& X# Q2 Y! F$ k$ k3 g6 C ( R( }; c% r+ N& S/ {' g4 h; s) A Hwho can explain why use R30 for attic. & P$ F8 S' E. v! Q! Q6 b
1#KochFord - R2 B( ^% X# }- k7 [( |The higher R value, The better insulation performance. # A* S. V+ h6 BIn winter, the hot air always floats up due to thermal buoyancy, so R value for the roof is normally higher than that for exterior wall. A5 R5 H5 v- j# b. M6 O9 A& f0 d6 UHope my answer helps.