how much difference in price and quality between R19 and R20 per square feet ??$ f+ q9 c" ^0 ?* R6 A; Q# L0 Q
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who can explain why use R30 for attic. + j @& @* v9 w5 w% Y" X6 r ! ^ A9 u a$ u9 x" O# ]* uThanks
1#KochFord ( n8 n1 c3 r' x- {$ X- mThe higher R value, The better insulation performance. ' l8 y* \1 ~1 Z' d1 jIn 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. : \4 G% s, Y8 N% |Hope my answer helps.