Repairing ice dam damage


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Old 04-11-08, 09:25 AM
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Repairing ice dam damage

I am going to be helping my parents repair ice dam damage to their roof. It is a 1 story house with a continuous roof line, and continuous aluminum gutter. The soffit extends 2 feet from the house the entire length, except in the middle where they have a bow window which extends all the way out to the edge of the soffit, and only the gutter extends beyond the window. This past winter, they started experiencing water coming into the bay through the window casement and the kitchen light box inside of the bay. The gutters had bad ice daming at the time. They live in an area which had a record amount of snow this winter.

New asphalt shingles were installed about 6 years ago, but they didn't have the old shingles removed.

What I would like to do is to remove about a 3 foot wide swath of shingles from above the bay, and extend a few feet to either side of the bay, then install Grace ice and water underlayment onto the plywood. The problem that concerns me is getting the underlayment under the gutter, which is continuous and can't be removed. Would it be acceptable to overlap the the underlayment OVER and into the gutter? Maybe a couple layers worth? Or does it absolutely have to go behind the gutter onto the facia?

Any suggestions would be greatly appreciated!
 
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Old 04-17-08, 04:13 PM
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The recommended practice is always to adhere the Grace Ice and Water Shield to the sheathing, folding it down over the front of the fascia. (or fascia cover, if aluminum fascia cover has been used. I suppose the thinking is that you're protecting the wood best by adhering the membrane to it, not something else.

But in practice, such as when attempting a repair as you are doing, it makes more sense to me to try to ascertain what's going to do the best job of stopping the problem. At the same time, you don't want the repair to be like a band-aid and just "patch" the problem.

I'd suggest that you remove the drip edge, fold some of the membrane over the fascia and onto the sheathing so that no water can get between the joint that exists between the top of the fascia and the bottom of the roof sheathing. Then replace the drip edge, applying it over the top of the membrane. The nails holes through the membrane should be self healing. You might want to make sure that they have "gutter apron" over your gutter, not d-style drip edge, which is not usually long enough to cover the back edge of the gutter.

I assume they don't want the membrane installed over the top of the gutter apron because of the potential for the membrane to not lay flat and seal properly, and you actually should fold the membrane down a couple inches over the front, which wouldn't look too hot since you could see it over the top of your gutter! Plus, if the gutter fills up with ice, water could still potentially back up under the gutter apron and leak behind the fascia. Actually wrapping the membrane over the fascia helps seal this potentially problematic area.

Sorry about the length of time your post went unanswered. It must have slipped through the cracks.
 
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Old 04-17-08, 04:44 PM
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Here's a pic of one fellow's solution to roof edge leaks. You'll notice he folded the membrane over the edging, which was custom made from aluminum trip coil.
 
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Old 04-17-08, 05:44 PM
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When we see these sorts of problems at home inspections in my Chicago climate, we direct clients and contractors to the manufacturer's installation instructions for the specific installed brand of Waterproofing Shingle Underlayment (WSU) installed, for example here's the suggested CertainTeed Inc. detail for installing WSU to prevent ice backup from gutters .

The full installation instructions are here, CertainTeed specifically recommends against installing WSU over existing shingles.
 
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Old 04-17-08, 06:20 PM
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Actually, none of the below will solve the problem of the ice dams. It is the ice that's causing the problem, not the ice and snow shield installation. The only fix is to keep the melting snow flowing down the roof and to the ground through the gutters. If you don't it will continue to refreeze at the drip edge and build up until it works its way back up under your overhang and in to the house.

The fix, though not an inexpensive one, will save your parents over the long run. You can start by installing a self-regulating heat cable gutter melt system in the gutters and leaders. It can be manually activated or set up with a temperature/moisture sensor for automatic activation. This will keep the ice from refreezing in the gutters.

The next part will depend on whether you care about the esthetic value or a more complete design. You'll also need to keep the drip edge free from ice as well.

You can also run the self regulating cable up the roof in a zig-zag fashion to help prevent the freeze-up at the drip edge but there will be a very evident cable on the roof that looks much like black Romex cable. If you don't care about the look of a wire on the roof, that should take care of the bulk of the problem.

In lieu of the cable on the roof and, since you'll have to remove the shingles to repair the existing damage, you can splurge on the best under-shingle deicing system on the market. I'm not allowed to disclose the name because I sell it but if you have a sizeable budget and are willing to really fix the problem from ever happening again, search the net for Under Shingle Roof Deicing systems and I'm sure you'll find the bronze screen element that makes up the design.

Good luck with your parent water problems..
 
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Old 04-18-08, 10:24 PM
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Thanks for the replies. Fortunately the situation with the gutter wasn't as bad as I thought, so I went ahead the performed the fix earlier this week.

Here's a pic I took after I removed the 2 layers of shingles, in a swath about 3 feet wide and 3 feet past either extent of the bay window:

http://i134.photobucket.com/albums/q...2/IM000030.jpg

As you can see, I also removed the gutter apron and support brackets. My father insisted I cover the old nail holes with roofing cement. I guess it doesn't hurt.

As I removed the shingles, the point of water penetration was obvious - two soaking wet spots about 6" square right at the edge by the gutter. This gave me some confidence that I had removed enough shingles. I left the roof exposed overnight and by the next morning it had completely dried out. The integrity of the plywood was intact.

This is how I performed the fix.

1. I cut 12" strips of the Grace underlayment and attached them to the facia behind the gutter, just high enough so it was hidden by the gutter from below, yet covered the aluminum facia covering. About 7" overlapped onto the roof. I added a second 12" wide layer and staggered the joints.

2. I installed the new gutter apron and reinstalled the gutter support brackets.

3. I cut 3 ftx3ft sheets of the Grace underlayment and installed it OVER the gutter apron (only up to the corner, so it it can't be seen), and underneath the existing tar paper and shingles about 6". Each sheet was overlapped at the joints about 8". I wanted to use larger sized sheets, but it was extremely windy and even the 3x3 sheets were hard to manage. I had a two foot piece left over and attached that over the area where the water spots were. So these spots ended up having FOUR layers of underlayment on them!

4. I installed the new shingles, taking care to replace all the removed nails and using liberal amounts of roofing cement to hold down the tabs that had to be loosened.

All I can do now is cross my fingers and hope this works. It ended up costing only about $60 for the materials.
 
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Old 04-19-08, 05:10 AM
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It sounds like you've got a handle on it. I didn't see much overhang in the picture. If it repeats, I think all you'd need is gutter/downspout melting.
Good luck!
 
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Old 04-19-08, 07:32 AM
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Thanks. I had meant to acknowledge your original post last night, but ran out of time. At first we thought about installing some kind of deicing system, but after seeing how little the ice appeared to penetrate into the roofing (only 6"), we are just going to let the underlayment do its thing and see if that works.

If this had just been a normal winter, we might also be more proactive, but there was nearly 100" of snowfall, which was a record (normal is around 45"). And even though the gutters fill with ice just about every winter, this was the first time in the house's 20 year life that it actually had a problem with water coming into the house.
 
 

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