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churl
Member
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# Posted: 12 Jun 2025 03:25pm
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Hi there,
We need to winterize our cabin's roof (in Quebec) and we're just debating whether to go with a hot roof or cold roof.
I reached out to you all last year about this:
https://www.small-cabin.com/forum/2_12142_0.html
Our cabin has no attic and cathedral ceilings, with no ventilation, and a very thin roof. This caused problems last winter.
We have reached out to several roofers for quotes.
Several roofers have proposed adding a second cold roof layered on top of the first one with soffits, insulation and air space in between, and a ridge vent at the top. This is the less pricey option, running around $20k.
Another roofer has proposed a hot roof option, with R-42 insulation and no air space, running around $30k. He tells me that a cold roof is a worse option because the angle of our roof is not steep enough (around 25-30 degrees) to keep off the snow. There would be a risk of it getting covered and leading to an ice dam. He also said there was a risk that critters could get inside the air space. And the roof would not last as long.
What do you think is the best option? Do you have any experience with this?
Any input appreciated!
--Chris
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Brettny
Member
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# Posted: 13 Jun 2025 10:40am
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Seasonal cabin?
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churl
Member
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# Posted: 13 Jun 2025 10:41am
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The rest of the cabin is winterized, four season. But the roof is not. We want to winterize the roof.
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DRP
Member
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# Posted: 13 Jun 2025 06:22pm - Edited by: DRP
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What is there now, say from inside to out. What were the issues... and what would you like to do or achieve?
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churl
Member
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# Posted: 13 Jun 2025 06:34pm
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Right now we have a non-winterized roof that has no vents and no attic.
The problem with this is that we need to have a buffer zone enabling the transfer of heat between the inside and outside. Without an ventilated attic, there is no buffer zone, which can be really hard on the roof. In the winter, the direct contact between hot and cold leads to leaks and ice dams.
So, our aim is to create a buffer zone to make the transition between hot and cold more gradual. This should prevent ice dams and leaks in the winter and also keep the cabin cooler in the summer.
There is a debate on the best way to do this.
Some folks argue that a "hot roof" is preferable. That means there's no ventilation, just a lot of insulation. But others argue that this can lead to condensation and mold inside. It's also a lot pricier.
Others argue for a "cold roof," which is more traditional. That means, in the absence of an attic, that you build a second roof on top of your existing roof to create an air pocket, which serves the function of an attic, creating a buffer zone between hot and cold. But you need vents for that. And we're being told that, with a lot of snow fall, those vents could be covered over, thus preventing the circulation of air.
So, we're just wondering whether anyone else has experience with these different solutions and if they think one is superior to the other.
Thanks!
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razmichael
Member
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# Posted: 14 Jun 2025 06:12am
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You don’t detail the size, if the inside ceiling is already finished etc and these details would certainly impact the cost of a hot roof. My Quebec 16x24 uses a spray foam hot roof but we did it during the build as part of the spray foam. $30k estimate seems high but it would depend on size and how much of a retro fit it would be. I would suggest you contact a couple more crews (don’t need to be roofers) to double check the cost of spray foam then decide. Both methods, if done properly, should work. The key to a hot roof is a good seal and enough R value.
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Aklogcabin
Member
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# Posted: 14 Jun 2025 09:06am - Edited by: Aklogcabin
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Kinda gotta choose between doing the work outside or inside. Inside you'll probably loose the astecic you now have. But probably much cheaper and sometime that you can do yourself, if you want.
Id probably go cold attic inside with good sealed vapor barrier and R-38 rockwool fire n sound insulation. Allow for airflow above the installation from the soffit to a ridge vent.
Important to protect your structure. And have a cabin that is usable and built to last.
Just spitballing here so hopefully gives you some thoughts
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churl
Member
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# Posted: 14 Jun 2025 09:10am
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That's really helpful. Thanks!
We definitely want to do the work outside. We'd lose too much ceiling inside. We don't have that much space.
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Notes
Member
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# Posted: 14 Jun 2025 11:31am
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Check out Green Building Advisor and search low slope roof vented above deck. Lots of info on vented and non vented systems.
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gcrank1
Member
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# Posted: 14 Jun 2025 11:48am - Edited by: gcrank1
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That pic looks like what I had in mind if I had built my own this last time, though for an essentially 3 season 'hunting & fishing recreational' cabin here I would not have had to use as much insulation.
Even so, planning for an unanticipated future isn't a bad idea.
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Brettny
Member
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# Posted: 15 Jun 2025 07:37am
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"But others argue that this can lead to condensation and mold inside. It's also a lot pricier" for condensation to form you need air space. With no air space you move all that condensation outside of the roof.
Since you want to do all this work outside I would find a contractor that will lay down foam board over the roof and strap the top then put the roof on.
As to price..idk as I do all my own work. I have under $25k into our whole 20x32' 2 story 4 season cabin. We have R45 in the roof including 4in foam right up against the bottom of the roof. We have no vents as there not needed.
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