We’re going to be talking to a contractor this month about a remodel of our upstairs, which is currently one large converted 1/2 story attic.
We want to add a dormer to one side to add a bath, and then likely gut the inside, leaving me to go back and re-finish it all.
I’m not sure how much longer our current roof is good for, but am figuring on ‘since they’re up there cutting holes in it, let’s see if we should re-roof while we’re at it’.
Which leads me to this question: in the summer, this space is HOT and really works the A/C. In the winter, it’s cold. The reason is that the roof is built with 2×4 rafters insulated with fiberglass.
If we get to the point of re-roofing, are there some viable options to increase the insulation at that point? Can we add 2″ foam insulation and cover with metal roofing? Anyway to add insulation with standard shingles? What’s the most practical way of getting more insulation up there? We’re rather not take up space inside if possible.
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From what I've read the best option you have is to have a contractor spray foam into the area. Two part do it yourself kits are available if the area is not to large. Ed
In MN you should probably have R-39. At R-6 per inch, that's 6 1/2" of foam (these are averages.) Are your rafters a full 4" thick? Probably, so you just need another 2 1/2".
To get that you could strip the roof, lay down a layer of 1 1/2" and a layer of 2" (seams staggered and taped), run strapping on top of that, and new roof sheathing. This also facilitates a vented roof which is always a good idea.
Sounds expensive, but likely the best option. Is the extra sheathing a concert weight-wise for the 2x4 rafters?Oh, these are 3.5" 2x4s. Which is odd, given the age of the house ('27)
Maybe. Probably. Foam is heavy too.
Hate to say it, but you might be best off starting over....2x12 rafters with denspak cellulose.