Ice Dam Resolution?

capeowner · 02-15-2009, 06:47 AM

I have a Cape with a pretty bad ice dam. We just reshingled the house two years ago, but didn't know there was no ice and water shield underneath the first layer and didn't know to add it. Now we have a big hole in our living room ceiling just under where the ridge of the eves roofing meets the rest of the roof. I understand ventilation is a problem, and we are looking into that, but with the ice and water shield, i'm being told different stories. 3' up from the edge of the roof or 6'? I found this article that said the new "norm" is 6' up? can someone just tell me how much ice and water shield I need to apply?

Thanks

Bob Mariani · 02-15-2009, 08:29 AM

3' is minimum. I use it on rake and eave and all valleys and around all roof penetrations. But if you re-did the roof was the ridge and soffit vents added? Maybe not since they left the old shingles on.

capeowner · 02-19-2009, 09:11 AM

Hi Bob, thank you for your response. we did put in a ridge vent before, but not a soffet (sp) vent, guess we cant, but we just put a vented drip edge on. we ended up going the 6' up and totally up the valley just to be on the safe side. and on the inside we are fixing the ventilation and insulation. thanks again.

Bob Mariani · 02-19-2009, 09:49 AM

if by vented drip edge you mean smartvents then you are good.

OldNBroken · 02-19-2009, 10:09 AM

The distance up from the eaves is not based on your roof, it is based on your exterior walls. Proper installation is minimum of 2 feet beyond all exterior walls. How far up the roof depends on your soffit overhang and pitch of your roof. Each structure must be calculated accordingly. IE, if you have 12" soffits on a 6/12 that's going to put your exterior wall roughly 14" up the roofdeck, add two feet to that. Most ice/water is roughly 39" so one run would be adequate. If you have 2' soffits it changes the equation and you would need at least 1 1/2 runs. Hope that helps

Scuba_Dave · 02-19-2009, 10:12 AM

I use ice & water shield all the way up the roof
Compared to the possible damage its cheap insurance

New rood, ice & water shield, ridge & soffit vents, R38 insulation & rafter vents

I still had ice dams due to the repeat snow we had
I had one leak on the old front roof - I didn't roof that
Going up & removing the ice resolved the issue before any real damage was done. Majority of the water that leaks is on the 3 season porch, not in the house