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churl
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# Posted: 26 May 2024 18:09
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Hi there,
We just got an old cottage with a roof that has no vents and no attic.
We're just looking for some advice in determining the nature and degree of the problem as well as figuring out potential solutions.
THE PROBLEMS
It seems like the core problem is that a vented attic provides 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 (although there seems to be debate on just how much of a problem this is). The bigger problem seems to be the risk of condensation (and consequently mould) inside the cottage.
POTENTIAL SHORT-TERM SOLUTIONS
1) HOT ROOF - One shorter term solution might be to add insulation to the roof and ceiling. We're considering covering the ceiling with a vapour barrier and then adding spray-on insulation and dry-wall. We could also add another layer of insulation to the roof outside.
2) FANS - This could be combined with ceiling fans blowing the air downward, keeping it circulating
3) HEAT PUMP? - We were also considering the utility of a heat pump in regulating the temperature and dehumidifying near the ceiling. Do you think this would work?
POTENTIAL LONG-TERM SOLUTIONS
1) BUILDING AN ATTIC - But we really don't want to do this, given that the cottage has a beautiful cathedral ceiling. We're wondering about the possibility of ventiliation without an attic.
2) Soffits - Can soffits be installed in a roof without an attic?
3) Second roof w/ridge vent - It seems like a pricier option is to build a second roof above the existing one and installing a ridge vent.
4) Other?
Does anyone have any experience with these options? What would work best?
Any advice is appreciated.
Thanks.
--Chris
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churl
Member
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# Posted: 26 May 2024 21:06
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I found this discussion to be really helpful: https://www.small-cabin.com/forum/2_6028_0.html
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Fanman
Member
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# Posted: 26 May 2024 21:15
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Is there already evidence of mold or other problems? If not you're probably fine.
Our cabin is the same; the visible (cathedral) ceiling is the roof planking (1" rough sawn chestnut boards on log rafters). We can see the roofing felt through the gaps. No problems, though the cabin is well ventilated, it's drafty and has lots of windows.
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ICC
Member
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# Posted: 26 May 2024 21:31
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Interesting ceiling fanman. Lots of character.
My personal opinion is that such a roof/ceiling will not generally be a problem for moisture condensation. It will not be very energy efficient, which does bother me, but probably not produce any major health or structural issues, unless there is very low air circulation and the surfaces remain damp or wet for extended periods.
How old is the cabin, churl? Are there any discolored areas that might suggest having been too wet previously? Have you seen areas with obvious condensation or are your concerns mostly theoretical?
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razmichael
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# Posted: 27 May 2024 10:33 - Edited by: razmichael
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As ICC notes (and he has way more experience than I do), this may not be an issue so all I will add is that your short term #1 Hot Roof would not be short term but long term. No vapour barrier needed as the spray foam does that (assuming you use the correct type) and there should not be any need to add more on the outside if you can put in enough on the inside.
When we had our cabin done a number of years ago it was cheaper than I had expected (not cheap but cheaper) but this depends on your budget. Lots of advantages to keeping the heat out in summer and the heat in in winter (and as much as I love the sound of rain on the metal roof, it is nice to have it muffled a bit).
I'm not saying a Hot Roof does not have some disadvantages but it might be way easier and cheaper as a renovation.
EDIT - but I would hate to cover up that ceiling!
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paulz
Member
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# Posted: 27 May 2024 13:12
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Nice ceiling Fanman!
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Fanman
Member
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# Posted: 27 May 2024 18:08
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Quoting: paulz Nice ceiling Fanman!
Thanks... it's original (1928). Zero R-value, of course, it was built a a summer place but with a good fire going it's quite comfortable in the winter.
Some of the neighboring cabins had the ceiling painted to "brighten them up", I guess, but it destroys the aesthetic... I'm glad nobody did that to ours. The dark wood does make it dark inside but the skylight on the other side helps a lot.
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Notes
Member
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# Posted: 27 May 2024 19:09
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Maybe this may help. Many topics on Green Building Advisor.
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Brettny
Member
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# Posted: 28 May 2024 00:06
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Unless your having a problem I wouldnt touch it since its alreaty built. If you are having a problem this is all speculation u til you open things up.
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jsahara24
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# Posted: 28 May 2024 19:10
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The rec room in my primary residence has a similar situation..... cathedral ceiling, pine t&g boards on top of the exposed rafters, then 1" of foam board, layer of osb, snow and ice shield and shingles....
I have not had any issues with condensation. I do have a lot of issues with heat loss/gain....No issues in the winter with the wood stove in there, but in the summer its almost impossible to use air conditioning....
pic of ceiling....
https://www.small-cabin.com/forum/shared_files/uploaded/10402/143981_2_o.jpg
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Brettny
Member
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# Posted: 28 May 2024 23:22
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If you have issues with heat/cool loss in that room then you prob have mold/condensation at your roof decking.
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KinAlberta
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# Posted: 12 Jun 2024 01:03 - Edited by: KinAlberta
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I’d rather leave the interior as is and upgrade the exterior with strapping for an airspace and a raised layer of new sheathing.
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