how much difference in price and quality between R19 and R20 per square feet ?? 1 m& [3 b3 R$ A: d# N. h z7 k* q/ a* v: @* l* g' ~$ o
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who can explain why use R30 for attic. * Y% v( Y5 d# C+ Z5 ]- E% L: ]6 G1 n: S; T8 Y4 Q+ `5 F
Thanks
1#KochFord7 x) U i4 E) _% Q
The higher R value, The better insulation performance./ x1 n! h. H" A
In 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.5 m3 z5 `3 l" U7 [1 b
Hope my answer helps.