Problems with roofing and ventilating house
Hi,
My insurance company has agreed to replace the roof, including the decking (sheathing), and ventilation, in my Cape Cod home in Dayton, Ohio. I have a refinished, vaulted second floor, with a small attic peak. All of this was there when I bought the home 3 years ago (I think it was done in 1998).
Thinking this would be a chance to improve the insulation, I began to investigate what to do. Now I am completely baffled, both online sources and contractors have given me such divergent advise.
This is what I know of my houses structure.
I have asphalt shingles
I have no soffit vents.
I have turtle vents and gable vents.
Rafters are 2 by 6.
I have R-19 batts crammed in the rafter along with styrofoam baffles (approximately 2 inches in depth). Thus the batts are compressed to roughly 3.5 in. This material runs from the knee wall top to the small attic floor and peak area (3ft or so triangle).
I appear to have more substantial insulation on the floor rafters below the knee wall and assume I do in the small attic (I have no accesses to it).
I have no idea what to do. Thanks for any advice.
Thanks, Todd
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
James,
You have two choices: you can build an unvented roof assembly or a vented roof assembly. Either approach can work, as long as you get the details right.
At a minimum, you have to make sure that your insulation is thick enough to meet code requirements. You can't do that with 2x6 rafters, so you will have to make your roof thicker -- either by adding insulation on top of your roof sheathing, or by building down your ceiling to provide more room for insulation.
All of the options are clearly explained in this article: How to Build an Insulated Cathedral Ceiling.