dormer flashing

[John Dirks Jr]

I could not see the normal exposed flashing at the base of the dormer. From in the attic I saw a membrane at the bottom portion of the window. I'm still not sure if this takes care of the need for a step flashing at the base of the dormer. Do you think it's likely the membrane that is visible from the attic extends to between the shingles at the outside?

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[Jim Katen]

I could not see the normal exposed flashing at the base of the dormer. From in the attic I saw a membrane at the bottom portion of the window. I'm still not sure if this takes care of the need for a step flashing at the base of the dormer. Do you think it's likely the membrane that is visible from the attic extends to between the shingles at the outside?

Let's see, you have to choose one of two possible scenarios:

1. The installers were clever and careful enough to design and install a difficult, subtle, and completely original flashing technique.

2. The installers were dumbasses who simply forgot to install the apron flashing.

Gosh, that's a hard one.

[John Dirks Jr]

Actually, it could be there. Consider they might be using that thin Grace membrane.

If you count the number or courses from the gutter up to the dormer, there is is 8 full courses. The last one (9th) under the base of the dormer is only 1/2 of a shingle cut lengthwise. There could be a flashing membrane under there.

That was my thinking anyway. Although, it's also certainly possible that there is not a proper flashing there.

Feel free to criticize me this if you think I need it. It was writen up as follows;

Step flashing is not visible at the base of the dormer window structures. Normally, a step flashing is visible at this location. Its purpose is to prevent water from getting under the shingles at this junction. It's possible that a flashing detail is covered by a course of shingles but I cannot verify that in the scope of this inspection. Check with the builder to insure proper flashing detail for prevention of water intrusion at the base of the dormer windows on the roof.

[Jim Katen]

So you think that having water run underneath 8 courses of shingles is an acceptable way to flash a roof?

[John Dirks Jr]

So you think that having water run underneath 8 courses of shingles is an acceptable way to flash a roof?

I don't think that.

I'm sure you've seen the flashing covered with a 1/2 height shingle just below the dormer. Haven't you?

[Jim Katen]

Unless the metal apron flashing is hiding under that top course of shingles, (And that course is just stuck on with mastic to hide the flashing.) then I'd say that it's flat-out done wrong and needs to be reinstalled properly.

Presumably you would have been able to tell if the apron flashing was hiding under there.

[John Dirks Jr]

So you think that having water run underneath 8 courses of shingles is an acceptable way to flash a roof?

I now see that the comment I wrote is poorly written that would suggest I might think that. But as I said above, that top 1/2 height shingle under the dormer could be concealing a flashing that sufficiently covers the last full course. That would prevent leaking, right?

[Jim Katen]

So you think that having water run underneath 8 courses of shingles is an acceptable way to flash a roof?

I now see that the comment I wrote is poorly written that would suggest I might think that. But as I said above, that top 1/2 height shingle under the dormer could be concealing a flashing that sufficiently covers the last full course. That would prevent leaking, right?

Sorry I misunderstood. If it's metal flashing, then yes. It's fine to do it that way. If you're talking about Vycor or Ice & Water Shield, or something like that, no. That's not an appropriate use of those materials.

[John Dirks Jr]

Well, my comment could be confusing, especially if read by someone who knows exactly how the the flashing should be. I knew what I was thinking but the words didn't come out just right.

The bold part should have indicated the possibility of a 1/2 height shingle covering the flashing rather than implanting the idea that flashing beneath a full course is correct; which it certainly is not.

Step flashing is not visible at the base of the dormer window structures. Normally, a step flashing is visible at this location. Its purpose is to prevent water from getting under the shingles at this junction. It's possible that a flashing detail is covered by a course of shingles but I cannot verify that in the scope of this inspection. Check with the builder to insure proper flashing detail for prevention of water intrusion at the base of the dormer windows on the roof.

[Jim Katen]

Well, my comment could be confusing, especially if read by someone who knows exactly how the the flashing should be. I knew what I was thinking but the words didn't come out just right.

The bold part should have indicated the possibility of a 1/2 height shingle covering the flashing rather than implanting the idea that flashing beneath a full course is correct; which it certainly is not.

Step flashing is not visible at the base of the dormer window structures. Normally, a step flashing is visible at this location. Its purpose is to prevent water from getting under the shingles at this junction. It's possible that a flashing detail is covered by a course of shingles but I cannot verify that in the scope of this inspection. Check with the builder to insure proper flashing detail for prevention of water intrusion at the base of the dormer windows on the roof.

It's not step flashing, it's apron flashing.

At the front edges of the dormers, the joints between the dormer walls and the roof shingles should be flashed to prevent leaks. I don't see any flashing in these locations. If the flashing is there, then it's hidden by a course of shingles. Ask the builder to confirm that the front edges of the dormers are properly flashed with metal apron flashing.

Why couldn't you tell if it was there or not? Couldn't you have just opened the window, leaned out and poked at the shingles? Or reached out from the top of a ladder?

I try really hard to avoid the need for that kind of ambiguous note in a report.

[John Dirks Jr]

I don't like sloughing the conclusion like that either but sometimes it's the best one can reasonably do.

Too high for ladder work, for me anyway.

My idea was to do exactly as you suggested by opening the window. I got within 5 feet by navigating through the upper trusses in the attic. The last 5 feet would have required too much disturbance of loose fill insulation to make it worth it for me. Except for lack of weather strip at the hatch, the rest of the insulation looked too good for me to be the first one mucking it up.

Apron flashing...got it. Thanks.

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[Brandon Whitmore]

It's not step flashing, it's apron flashing.

I've always called it roof to wall flashing unless at the base of a chimney. Crap, now I have to look it up to see if I've been wrong all these years...

[Jim Katen]

Apron flashing, front wall flashing, face flashing, . . .

Not step flashing.

[Brandon Whitmore]

Not step flashing.

Agreed. Luckily I read the entire thread before posting.