Roofing issues concern local homeowner

  • Step flashing is required on the joint where a lower roof meets a second-story wall.

    Step flashing is required on the joint where a lower roof meets a second-story wall.

Posted11/25/2018 6:00 AM

Q. I'll be re-roofing my tri-level home in the spring. One roofer said on the part where the lower roof meets the siding, the flashing is called baby tins and they run up behind the siding. Is that the best flashing solution for this area, and should that be replaced when I re-roof? He seemed to think it would not need replacing.

The existing plank decking is coming off so they can sister the joists as there is a sag in the roof. A Shinglevent II ridge vent will be installed to work with the current soffit ventilation. These is no gable vent as the interior is a vaulted ceiling. Are there any concerns that come to mind to investigate when the plank decking is removed. I have not experienced any problems in the 24 years I have been here.


Also, there appears to be flashing from the edge of the roof that overhangs the back edge of the gutter. Is that the correct way to address that area in terms of flashing.

Finally, are two layers of ice water shield enough to combat the Chicago winters? The front of the home faces north, and the area of most concern is where the baby tin flashing is. I am considering a third layer out just to be on the safe side on that part of the roof.

A. It's interesting how building terms can vary regionally. I have never heard the mandatory step flashing where a lower roof meets a second-story wall called baby tins.

Yes, it is the best and only way flashing should be installed: one piece under each shingle. The vertical leg of these "baby tins" is fastened to the house wall sheathing and must be covered with the felt or housewrap covering the sheathing before the siding is applied. Some builders even apply a water and ice protective membrane at this joint as added insurance against leakage.

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The horizontal legs are placed under each shingle to let any water that gets under the shingles drain over the shingle course immediately below. If, by ignorance, someone runs a single piece of flashing (known as running flashing) under the siding and the shingles on the full length of this roof connection, any water penetration under the shingles will spread laterally, damaging the roof sheathing. I have seen such damage resulting in plywood delamination and rot as far as 6 feet from the joint of the lower roof and the gable wall. OSB is often so compromised as to have to be replaced, as it cannot withstand moisture as well as plywood.

The step flashing may not need to be replaced, depending on its condition, and it saves the difficulty and cost of removing some siding for new flashing to be installed properly. In your case, if the new decking is of the same thickness as the existing one being removed, the existing flashing may be OK. Each piece of step flashing must lay flat under each shingle so the shingles are not lifted by a poorly fitting flashing.

You mention that the lower roof deck is sagging and that this is a cathedral (vaulted) ceiling. I wonder why? I hope that when the plank sheathing is removed, you will not find extensive damage. These ceilings are candidates for accumulation of condensation and worse because it is very difficult to vent them adequately.

Installing Shinglevent II ridge vent is a good idea if there are provisions for effective ventilation, but that depends on the type of insulation there is and whether or not it leaves an adequate air space for effective ventilation. If you find serious problems, you may have to consider replacing the existing insulation with closed-cell polyurethane sprayed from above in order not to repeat the damage. A minimum of 1½ inches clear space for ventilation must be left.


Your second photo is not clear enough for me to understand how the drip edge is installed, but your description that it overhangs the back edge of the gutter is the best way to ensure that water dripping off the roof will not get behind the gutter and rot the fascia. This is the way it should always be done.

I assume that when you mention two layers of ice and water protective membrane, you are intending on having them installed at the roof eaves going 6 feet up the roof. Your roof overhangs look like they are more than 1 foot wide, so it makes sense to add a second layer since the recommendation is that the membrane should go up 2 feet higher than the intersection of the wall below the roof with the roof itself. A third layer does not seem to be necessary, but total coverage of a roof with this type of membrane is getting more prevalent.

Q. Our house is 30 years old. Our old shower door was a sliding two-door, framed in aluminum. We had it replaced with a new all glass door, no aluminum framing. The problem is, one of the walls is not plumb. The bottom of the door hits the frame, but at the top of the door there is a gap (not a huge gap, maybe one-eighth inch). When I take a shower, there is moisture on the floor. I imagine it's spray getting through this gap. The old door had larger channels for the door to fit in, so it was not a problem with the old door. The new one has a much smaller channel, hence the problem. Have you ever seen/heard of this before? And if so, is there a solution?

A. Yes, it's a relatively common problem, but in most cases the installers are able to adjust the door to minimize, if not eliminate, the gap. Have you asked the installers if they can make some adjustment to the appropriate glass panel? If not, can they install an extension of the frame to prevent water from bypassing the door? The extension should be of the same metal as the door frame and does not have to be big considering the small gap you describe.

But first, I would suggest you hang a towel over the top of the door frame and see if the moisture on the floor is really due to this gap; it may not be, considering it is at the top of the door. Alternatively, the new glass door frame on the out-of-plumb wall can be shimmed to make it plumb and the space between it and the house wall trimmed.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He continues to take questions from readers for this column and his website, Email questions to

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