Quote Originally Posted by handymandan View Post
I have questions about attick insulation. I currently have fiberglass in the rafters. I'm getting conflicting information. Can I spray foam the roof rafters? Which will completely seal off the attick? Will this damage the shingles? Or am I better off to install more fiber glass?


Thanks, Erie PA
Some of the information provided here is only accounting for heat loss , which is only half the equation , heat gain is the other half .

The most economical bang for your buck would be to simply add more insulation on top of the existing , increasing the R value up to R40. Before doing so , seal all penetrations into the attic preventing air movement to and from the living space and attic. This will reduce heat gain/loss by another 15%.