damage from ice dams
After a very severe and snowy winter I have had alot of damage due to ice dams.
I have a cathedral ceiling in part of my home and all of the damage is in the ceiling areas without attic space.
I do not have an ice barrier currently under my asphalt shingles. The current roof is from 1994.
My concern is that it has more to do with insulation or lack of in the cathedral ceiling.
What kind or insulation and how much should be in that space to prevent the room air from heating the roof?
Re: damage from ice dams
Before getting into the how much insulation related part of your question..........
What is the pitch of the roof? 3/12 , 4/12, ???
If the pitch is too low on the entire roof, you're gonna need something more than insulation to prevent water leaks from ice dams.
Where exactly is the water entering? Last 4' of roof near edge....or higher up the roof? Along a valley perhaps?
I have to tear one down and redo this summer because of extensive leaks this winter due to ice dams. Much of that from freezing rain that made the entire roof an ice dam. Low pitch, covered with tree trash encouraged leakage when the ice eventually melted. That because the roof pitch is 2 1/2" in 12 and never should have been roofed with asphalt shingles without having the entire roof covered in I&W membrane first.
The ice at the edges of the roof was 8" thick middle of this winter. Gutters over-filled with ice, too. (Shoulda took pics) Busted it up with a sledge hammer and threw it on the ground. No fun.
It's a huge ranch house and is also located where there is virtually no wind. Snow sits on it and that's that. Eventually turns to ice and the no-fun begins.
Point being......more insulation isn't *always* the answer as sooner or later the sun will shine just enough on a near freezing day to turn any lingering snow accumulation into an ice dam/layer. More insulation can't prevent accumulations of freezing rain, either. Not implying that more insulation isn't appropriate in your situation, just pointing out that it can't be expected to resolve all problems in all situations. Many homes had severe ice-damming here this winter. Nature of the beast.....and a beast it was.