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Old 01-20-2019, 09:46 AM   #1
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Hot Roof


I have a late 1940s brick cape that is poorly insulated in NJ. There are 2 dormers in the front, and the back is a large shed dormer that runs the entire width of the house. Roof is asphalt and just turned 20 years old. I can see evidence of ice jam damage in the front with mild rot on the fascia. There are no soffit vents (there is no overhang) and no ridge vent, just a powered attic fan. The slopes and the front knee wall are covered in R13 bats.

There seems to be 4 options presented to me by various contractors. First is install soffit and ridge vents, put in ventilation baffles, and spray foam or insulate over that. Second is remove all drywall from the upstairs and sprayfoam the entire underside of the roof. 3rd is remove the roof decking, and sprayfoam the drywall from the outside. Final option is install foam insulation over the decking.

I like the last option since it involves no interior work. If I went that route, is there any heat issues with doing asphalt shingles? Should I remove all of the fiberglass? Does insulating a roof from the exterior cost substantially more with the various valleys and dormers?
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Old 01-20-2019, 09:58 AM   #2
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Re: Hot Roof


Just adding foam ventilation to the outside won't do much. Capes tend to be a bit of a headache to insulate and vent.
You need an air channel to ventilate, so just arbitrarily adding soffit and exhaust vents won't help either.

Couple of options, one is to build a cold roof over your existing. Lay down some 2x and sheet over that, creates a ventilation path under the roof, but doesn't address the insulation.
A couple manufacturers make panels that accomplish the same thing, but also add some insulation. Hunter I believe is the major manufacturer,however they are rather costly.
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Old 01-20-2019, 11:03 AM   #3
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Re: Hot Roof


A 5th option, admittedly expensive, would be to move the house to North Carolina or further south.
Cape Codes are a modern day nightmare in colder climates. The best possible solutions still fall short of current thoughts on energy efficiency in the north.
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Old 01-20-2019, 03:29 PM   #4
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Quote:
Originally Posted by PatChap View Post
Just adding foam ventilation to the outside won't do much. Capes tend to be a bit of a headache to insulate and vent.
You need an air channel to ventilate, so just arbitrarily adding soffit and exhaust vents won't help either.

Couple of options, one is to build a cold roof over your existing. Lay down some 2x and sheet over that, creates a ventilation path under the roof, but doesn't address the insulation.
A couple manufacturers make panels that accomplish the same thing, but also add some insulation. Hunter I believe is the major manufacturer,however they are rather costly.
Isn't applying multiple layers of foam sheets directly on the roof deck and putting shingles over that the same as covering the underside of the roof deck with spray foam? I would like to create a hot roof and not ventilate.

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Originally Posted by craig11152 View Post
A 5th option, admittedly expensive, would be to move the house to North Carolina or further south.
Cape Codes are a modern day nightmare in colder climates. The best possible solutions still fall short of current thoughts on energy efficiency in the north.
I wish that was an option- escape the snow, the traffic, and the high taxes. Unfortunately I have a job and can't pick and chose where I want to live or work.



The only saving grace of this house is the climate in NJ is somewhat mild and since it's a fairly small house with gas heating, I never seen to pay a lot for heating. Even if I could make the house perfectly sealed and reduce heating costs by half, it would only save me about $50/month.
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Old 01-20-2019, 06:54 PM   #5
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Re: Hot Roof


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Originally Posted by matt151617 View Post
Isn't applying multiple layers of foam sheets directly on the roof deck and putting shingles over that the same as covering the underside of the roof deck with spray foam? I would like to create a hot roof and not ventilate.

h.
Hot roofs are pretty new, and I have only dealt with spray foamed roofs.
I don't think foam board would accomplish the same thing and you would still need plywood on top to nail the shingles to.
You would be adding thickness to the roof ,so you would need to cut back the siding. The fascia size would also increase the same amount.
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