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Msradell
Premium Member
join:2008-12-25
Louisville, KY

Msradell to Glenn

Premium Member

to Glenn

Re: Insulating an A-Frame house

"Hot Deck" insulation systems are becoming quite normal these days especially when using spray foam insulation. These type installations provide for no airflow below the roof deck making the entire interior conditioned space. Studies have shown no decreases in shingle life expectancy! Especially in a climate like where this cabin is located it certainly wouldn't be a problem and would make insulating much simpler.

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey

Member

said by Msradell:

"Hot Deck" insulation systems are becoming quite normal these days especially when using spray foam insulation. These type installations provide for no airflow below the roof deck making the entire interior conditioned space. Studies have shown no decreases in shingle life expectancy!

This is the system I currently have. But I have wondered if I could reduce cooling load further by having that air space under the roof deck, where outside air would circulate underneath to dissipate whatever soaks through the deck. I also had heard of decking with an IR barrier (foil) but found it is not available here in the north.

In other words, with a hot deck, what additional measures to improve roof ventilation have a reasonable rate of return vs. doing nothing?

tschmidt
MVM
join:2000-11-12
Milford, NH
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tschmidt to Msradell

MVM

to Msradell
said by Msradell:

"Hot Deck" insulation systems are becoming quite normal these days especially when using spray foam insulation.

Interesting, our house is timber framed. Shell is stressed skin panels with 3.5" of Isocyanurate foam insulation (R-30).

The house faces due South we have always had ice dam problems in the North facing roof. When we re-shingled a couple of years ago added a ventilated roof deck on the North face. That has dramatically reduced ice buildup.

Even with high level of insulation melting snow will tend to freeze when it hits the cold drip edge at night.

If the OP decides to add rigid insulation to the roof deck he is going to need to add a deck over the insulation. Adding some strapping to raise the new deck off the insulation is cheap.

/tom

Glenn
I'D Rather Be Skiing
Premium Member
join:2000-10-05
Wallingford, CT

Glenn to Msradell

Premium Member

to Msradell
said by Msradell:

"Hot Deck" insulation systems are becoming quite normal these days especially when using spray foam insulation. These type installations provide for no airflow below the roof deck making the entire interior conditioned space. Studies have shown no decreases in shingle life expectancy! Especially in a climate like where this cabin is located it certainly wouldn't be a problem and would make insulating much simpler.

That's interesting...and good to know. So if I'm reading this (and some google results) correctly, I could, in theory, just add more insulation. Basically replace the old stuff with thicker, new stuff and be OK?

Msradell
Premium Member
join:2008-12-25
Louisville, KY

Msradell

Premium Member

said by Glenn:

said by Msradell:

"Hot Deck" insulation systems are becoming quite normal these days especially when using spray foam insulation. These type installations provide for no airflow below the roof deck making the entire interior conditioned space. Studies have shown no decreases in shingle life expectancy! Especially in a climate like where this cabin is located it certainly wouldn't be a problem and would make insulating much simpler.

That's interesting...and good to know. So if I'm reading this (and some google results) correctly, I could, in theory, just add more insulation. Basically replace the old stuff with thicker, new stuff and be OK?

All of the studies I've read have been done with spray foam insulation but I don't see where the same thing wouldn't apply for any type of insulation.

Glenn
I'D Rather Be Skiing
Premium Member
join:2000-10-05
Wallingford, CT

Glenn

Premium Member

Thanks. Sounds like this "may" be less involved than I thought.