Todd writes from Middlefield, Connecticut: "Trying to finish out an attic in a 1950's house. Unfortunately, making up the gable roof are 2x8 rafters at 12" O.C. I would like to get R-30 batt insulation rating. I already installed Duravent foam ventilation channels in each rafter space. Can I tack a 1"x1" onto the bottom of each rafter and use R-30C to attain that rating? If not, any other advice? Will tack on 2x3's if need be, but would prefer not to. Comments?"

Answer: I recommend Owens Corning Raft-R-Mate® attic vents for the ventilation side rather than 1 x 1s. As for insulation, you have a couple different options. I was not able to find a faced product for 12 inches on center, but here are a few unfaced products:

Thickness - R25 8"
Measurements - 12" x 48"
Ref Code - A50
Sq Ft - 96.00

Thickness - R30 91/2"
Measurements - 12" x 48"
Ref Code - C07
Sq Ft - 80.00
Pieces per package - 20

Thickness - R38 12"
Measurements - 12" x 48"
Ref Code - W10
Sq Ft - 64.00
Pieces per package - 16