how much difference between R19 and R20 insulation, need help, thanks

KochFord

how much difference in price and quality between R19 and R20 per square feet ??
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who can explain why use R30 for attic.
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爱城飞雪

1# KochFord
2 {% Q  G1 x+ B) ~The higher R value, The better insulation performance.
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.
Hope my answer helps.

爱城飞雪

1# KochFord
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R19 is not commonly used.

chic-yong

R值固然重要，但隔热材料更重要。即使R值相同，不同的隔热材料性能也是不一样的。

KochFord

谢谢楼上两位