Sistering roof rafters to increase space for insulation

[phinsperger (Paul Hinsperger, CMI)]

@Brian A. MacNeish

Paul:

One of the worst items handled in an attic renovation/conversion is the air leakage at the attic kneewall down through to the ceiling below. This is usually never properly airsealed and the outer attic is usually warm. This system can be made worse by adding gable end vents for the outer attic as they allow more air movement from the attic floor system and house below.

Yes I know that Brian. I didn’t say the low insulation level in the cathedral was the only reason, but one of the reasons. Both convection and conduction heat loss contribute to the problem. You must address both to have a well performing assembly.