Venting on a Cathedral Ceiling


#1

Location is upstate NY.
I am re-roofing a section of my home that has cathedral ceilings with a 2:12 slopes. The roof is about 15years old. Many of the shingles are curled and broken on the “sunnyâ€Â


#2

Unfortunately, you don’t have an easy fix here. The only way to get air movement through each rafter bay is to install continuous vent chutes throughout to hold down the insulation out of the way.
The pitch is another issue. I’m not sure about your shingles, but there aren’t any ridge vent manufacturers I’m aware of that recommend installing or honor warranty claims on a 2/12 pitch. But the first thing to do is clear a path for the air to move, otherwise your vents are mostly useless.


#3

Although it is not “right”, ventilation is tricky and at best an inexact science…
I’m not saying that if it isn’t broke don’t fix it. I can say that there’s been many a times I’ve torn roofs off w/ this exact same set-up and there has never been a problem.
OTOH, I’ve seen ventilation/ insulation done right, and there still might be a condensation problem that’ll pop up.
Since you are re-doing the roof, I’d tear it all off to the rafters and get it to breathe correctly.
It is simply a matter of playing the odds. Odds are if you do it right, you won’t have a problem.

2:12 slope you say?


#4

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#5

[quote=“twill59”]I’m not saying that if it isn’t broke don’t fix it. I can say that there’s been many a times I’ve torn roofs off w/ this exact same set-up and there has never been a problem…

Since you are re-doing the roof, I’d tear it all off to the rafters and get it to breathe correctly…

Odds are if you do it right, you won’t have a problem.[/quote]

Based on the fact that he is having a problem with curling, etc., he should do something to correct it.
And I agree 100% with the next two lines.


#6

It is risky to install a dim shingle on a 2/12. You can do it but it is really not designed for it. In those situations i feel more confident on a low slope application like flintlastic or liberty. It is colored for home use and is designed with a residental warranty unlike most low slope materials.\

Baffles are the only way to help your situation. With a ridge vent you can do this. You must remove all the wood and place the baffles in there.


#7

Curling is due to crappy/ worn out shingles. In this case prolly organics since he is NY.
I don’t know that I’ve ever seen a fiberglass shingle curl. I’ve seeen the felt buckle 'em


#8

ventilaton is tricky and you have to chose the wost of two evils. the first being the life of your shingles vs oil bill I also know northeast winters.

 shingle manufactures want all the ventilaton they can get.  this is because with a few statements from the legal departmet printed on their labels they can now offer better warranties.  anyone whos been around recalls when shingle warranties jumped up 5 years and nothing was different they didn't change the weight per square. this was through greater vetilation specs. keep your roof deck cool and dry, the singles last longer.

 on the other side of that you are now cooling your house.  it will be colder in the winter.  I have heard of pipes freezing and many poeple complaining "it was not like this before I had my roof done." well da! you cut holes in your house. yea its cooler when its real hot but that depends on your location.  

so you have to decide what you want. I have little ventilation and 25 inches of insulation. I hate paying that oil bill. my plywoods fine and will mostlikely out live me. the shingles will to. Past that I dont care. if my kids get my house in the end let them put thier own damn roof on I did.