how much difference in price and quality between R19 and R20 per square feet ??# e. O+ Q3 D0 V* D4 {0 r
$ W, C+ p; K1 k. x
4 s, J, @ N- `+ z' i% n& }. P# \( {( T
who can explain why use R30 for attic. ' F! R/ ]' t: W1 i/ B- m/ q h" @7 k2 e! j
3 c6 X( p c( z
Thanks
1#KochFord * t* |5 H5 t8 Q* f% \8 c9 C) ]The higher R value, The better insulation performance./ j- K ]+ @6 u: K0 {0 I
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.; `2 k, x" y* D
Hope my answer helps.