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nl908
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# Posted: 1 Oct 2015 09:15am
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Hi,
I have a cottage (not so small) and it's pretty old and doesn't have an attic. My general contractor gave me a quote for a new roof and it means raising the roof a little and adding ventilation and soffits. I got a different quote just to replace the shingles and its about $15k less expensive. So I'm wondering if its worth it to add the ventilation?
My place is in quebec, so the winters are pretty cold and i'm not too concerned about making it cool in the summer. Its just more of an issue of condensation. The ceilings are pretty high (almost A-frame) and so i'm sure there is a lot of water vapour getting up there. if i ensure there is a good vapour barrier, i guess that will help. i'm just wondering if the extra $15k is worth it for some ventilation in the roof that might not do much. what do you think???
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PA_Bound
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# Posted: 1 Oct 2015 11:41am
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I have to ask, if you have already been living in the cottage for some time (how long?) what is making you think about adding the ventilation now? Are you seeing symptoms of excess moisture, or related damage?
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Wilbour
Member
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# Posted: 1 Oct 2015 11:51am
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Could it be that for the period of time when you are away the roof gets overheated. When it's closed up during the day the sun beating down on the shingles is a killer.
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creeky
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# Posted: 1 Oct 2015 01:21pm
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i would put metal roof over the old shingles with a vented ridge. don't have to take the old shingles off.
just strap. clad. go.
you may get bats using the metal as a home for the night in the summer. bonus. fewer bugs.
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razmichael
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# Posted: 1 Oct 2015 02:35pm
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Quoting: nl908 f i ensure there is a good vapour barrier, i guess that will help.
Very hard to do properly without some leaks and it only takes a small hole.
Another option (in between the two extremes) is to go with a hot roof design eliminating the need for ventilation. Spray foam the underside to provide both insulation and the vapour barrier then just re-do the roof (metal over the shingles if you want). Alternative method is to put foam boards on top and then re-roof over this.
Loads of information on advantages and disadvantages of hot vs cold roof with many opinions (and some facts). I did my cabin (also in Quebec) with spray foam, although more to make it simple to do the roof as the build was DIY. Bonus is cooler in summer - not really used in the winter.
I know that some of the later research does show that the temperature difference on shingles is not nearly as much as some think (and they actually cool down faster in the evening). Put metal on and it doesn't matter.
Here is one link to an article on the difference
Air Sealing: The Hot-Roof Option
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silverwaterlady
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# Posted: 1 Oct 2015 10:12pm
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Just got a new roof on my city home. This house is old and not up to code. The shingles on my roof were curled at the edges due to the lack of ventilation in the soffits.
I am having vents installed so that my roof will last longer.
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Borrego
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# Posted: 1 Oct 2015 10:20pm
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Vents are really important. Having said that $15k sounds high. I would look into other systems like ridge vents, etc...
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razmichael
Member
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# Posted: 2 Oct 2015 11:22am
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Not that I want to start a big argument over this (because I do not have the personal experience to back anything up), but the venting issue is not so simple and the hot roof design can be a great option in many circumstances. Venting serves slightly different purposes in hot and cold climates and everyone has lots of experience with it but there is also a lot of real evidence that things like the impact on shingle life is really not nearly as great as some might think. The term "hot roof" conjures up something that sounds really bad but the temperature difference is, in fact, not that great and, with the availability of less expensive spray foam solutions (or the alternative methods), it can be a cheaper and better fix for many situations. Couple more links worth reading if interested.
GreenBuilding Report
BuildingScience
Again, I'm not saying it is the only way to go, just a good alternative in some circumstances.
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