Ice Dams Around Dormers

Karen Bloom is a subscriber to my newsletter and lives in Austin, TX. However, she and her husband also own a home in Memphis, TN that's having major issues with ice dams around her dormers. Here's her full report:

"Hi Tim,  opens in a new windowI get your newsletter and really enjoy it.

We have a house in Memphis, TN in which we've had ice dams for the last two years. We've had some atypical weather in Memphis, with freezing, thawing and refreezing.

The ice dam doesn't form in the gutters, as it's not that much all over, but about 7-10 inches gets up against a dormer on the house over the front entry.

Here's a photo of the ice dam at Karen's house. This is a photo of a photo. You're probably looking at the roofer's cell phone screen. Photo credit: Anonymous roofer and Karen Bloom

Last year we had to replace the drywall, paint and floors in the entry, dining and living rooms and had a roofer come and "fix" the roof so it would not happen again.  It happened again.

I looked at your videos on ice dams and though one roofer is touting ice and water shields in Memphis, we don't need a total tear off yet.  What would you recommend for that one area?

The water gets up against the small area of siding on the dormer (only the one, there are 3) and is causing the wood to rot at the bottom. It's a "dead space" there, I've been told by another highly regarded roofer that the water, when it melts from the ice, has nowhere to go.

I like your idea of radiant barrier. We have a walk-in attic in that house and the roof pitch is very steep.

This is a house we lived in, but due to my husband's father's ill health, we moved back to Texas and had to put a tenant in the house, due to the crummy market. (Excellent tenant, though!)

We're at a loss, with all of the options and gimmicks and heating elements out there. We really need to do something to mitigate this now. Can you help us figure this out?"

Here's my answer:

Karen, if you hired my to fix this problem, I'd be tearing off the siding on that side of the dormer.

Even though you just re-roofed, it's not an issue to take shingles off the roof. They appear from your photo to be ones that are easy to match. It's easy to take them off and easy to replace them.

I'd tear off the shingles going up that valley to just past the valley farther up that's created by the dormer roof. I'd also be tearing off the first three feet of the shingles on the steep roof face that's CRASHING into the dormer.

I'd also be tearing off the shingles down to the gutter line below the valley as I assume the gutter line is really close to the spot where the roofer was on a ladder taking this photo.

opens in a new windowI'd then install opens in a new windowGrace Ice & Water Shield® on the exposed roof deck and up the side of the dormer tying it into the brick as best as possible.

To do this right, I'd probably be installing custom 40-pound tin flashing up and slightly around the left corner of the brickwork FIRST. This would be soldered and extend about a foot or two up the valley and at least 9 inches up the sloped side wall of the dormer.

The Grace Ice & Water Shield® would lap over the tin ensuring NO WATER could ever leak between the brick and wood structure of the dormer. That's a VERY TRICKY construction detail.

When the siding is reinstalled, it's IMPERATIVE that it's all cut to fit first and then the back, front and ALL EDGES are primed and get two coats of paint. This way water can't seep up into the wood where it's close to the roofing materials.