Ice daming

[mreynolds]

I have a friend with a roof we did last summer, we reroofed it, added ice and rain guard, then shingled over top of it. There are no gutters on the roof edge and it has drip edge. Currently it is ice daming, water is leaking through/down the exterior wall. It mostly occurs in a corner where there are two different level roof, but it will occasionally show up through the windows down the exterior walls. What are some possible cures for this???

[Rich]

Where you say 2 different level roofs - does one level butt into a wall? If so I would check there first for step flashing all the way down.
By mostly do you mean there are other places it's leaking also?
Grumpy may have some better ideas for you.

[mreynolds]

Yes, the one level does butt into the wall. Mostly leaking in that area, but will occasionally leak farther down (horizontally) near some windows. This house is a nightmare as far as roofing goes. It was an old farm house that has several additions. I always joke with him that his roof line would cost more to build than a new house.

[grumpydasmurf]

Typically your ice shield should cover at least 24" inside the exterior wall. If you have a 3' over hang and installed 3' of ice shield then your interior wall has zero protection. If it's a 2' overhang with a steep slope, and you installed 3' of ice shield, then you still have zero protection.

Water chooses the path of least resistance. The only way to truly tell where the water is entering is in the attic. Roof-to-wall intersections are a pain in the BUTT. Did you wrap the ice shield 1' up the wall?

If the roof was a nightmare, why didn't your friend have a pro do it?

Ice damning occurs because of improper ventilation and/or insulation of the attic space. In some areas it's impossible to avoid evwn with the best ventilation and insulation. Ice shield doesn't prevent Ice damns. It prevents the ice from coming into the house.

One other thing, condensation is sometimes mistaken for ice damning. If the house has poor ventilation, or bathroom/kitchen vents exhaust directly into the attic, then the moisture gets trapped in the attic, freezes in the cold and thaws in the warm. Like I said it's sometimes mistaken for an ince damn because the symptoms are the same AND they occur from the same reasons, freeze/thaw.

[mreynolds]

Thanks Grumpy, that made a lot of sense.

1. Here is what I found out after further investigation. This roof was built over an older part of the house, it has a wall that is blocking air flow from the eve vents to the ridge vents.
2. Here is the kicker, which you hit on. There happens to be an indoor hot tub below this roof also that is on year round.
3. We didn't lap the ice guard up the butt wall either.

This should make for a pretty interesting project this summer. Thanks again.

[grumpydasmurf]

LOL If I had a dollar for every time I have rattled similiar words this year I'd be rich :)

Oh no wait, we already have a Rich

Oh man I'm too funny!

[Rich]

haha.. do I need to change my name again?