Insulation Savings

[JRC]

Thanks Phil!

The shingles were replaced by the previous owner 5-6 years ago. There is no ridge vent or soffit vents. The wood soffits were covered in aluminum and I believe a piece a trim was removed leaving a very small gap (just large enough for birds and bats to enter the attic!) but not large enough to be a proper vent IMO. There is a small gable vent on two (the larger) of the four gable ends.

The hot roof debate is an interesting one to read/study! I looked at the CertainTeed warranty information and a non-vented roof is covered if the insulation is installed directly to an approved roof deck. They mention plywood or OSB as acceptable. Our roof deck is the original boards installed over 100 years ago.

Phil's right ... and even if you think your house has no soffit vents, isn't it balloon framed? If so, that provides I think more than enough venting for your attic as all the wall cavities are open channels from the open crawlspace under the house to the attic. Assuming your house is raised and does not have an enclosed basement, that is.

The OP is from Southern Minnesota, and an open crawl-space is very uncommon in the north.

[bankeny]

Yup! Full basement here in Minnesota! So no venting through the wall cavities. No insulation in the wall cavities either! But we'll focus on the roof first.

There sure are a lot of insulation options! The rigid foam idea is an interesting one. I could have soffit and ridge vents installed and create an air channel with rigid foam. Then spray foam onto that to air seal and and provide a vapor barrier.

Again, the hot roof debate is an interesting one!