Skylights at slope transition

[Michael D. Thomas]

Two skylights installed bridging a transition between roof pitches. No way to ascertain how this was framed. Not leaking at the moment, but it's hard for me to believe this is "right"... so I'm a bit conflicted as to if/how to report this. Suggestions?

Also, what's the name for a roof with this sort of slope transition near the eaves - I knew it once, but can't seem to dredge it up at the moment...

[John Nosworthy]

Mike,
Its probably best not to comment on that which you can't be certain of (the framing for instance). We can't tell from you photo how close the two units sit to each other, and therefore be able to guess as to framing details in this region. I don't see anything obviously wrong with the flashing in the one photo. What makes you think it's "not right", especially if there is no evidence of leaking, stains, etc.? How long has it been installed would be nice to know. Time is the best test for skylights. If you feel inclined, you may report the installation as "unconventional", appears properly flashed, and no apparent evidence of leaking.

[Michael D. Thomas]

My concern is that I've never seen these skylights installed using (I assume, from the uniform color and appearance of the various flashing components) the factory flashing on anything but a single plane roof surface. Hopefully, the installers built a small curb angled on the bottom as required to meet the sheathing and providing a "flat" surface to which to mount the skylight, and didn't just bridge the upper and lower roof surfaces with the skylight, with its body supported only at the top and bottom.

That said this appeared to be a careful and "workmanlike" job - not a hack - and it's not currently leaking (I Tramexed the interior perimeter of the skylights), and assuming that they used step flashing designed for a higher curb in the middle, I don't have an objective reason to even suspect it's wrong.

So I doubt that I'll mention in the report, and just content myself with having verbally informed the clients that ALL skylights are potential sources of leaks, and that if they observe any evidence of leakage, to get it investigated, stat.

Still, it bothers me. And I wish I could find a better way to express my (admittedly entirely theoretical) concerns - I just have the feeling that in a year or two I'm going to be getting a call about "those leaky skylights".

[John Nosworthy]

Mike,
I think you are going to be fine here. You've confirmed that the step flashing in the middle is higher as it would need to be, and suggest that it is the exact same color of the head and tail flashings. If it is the brand of skylight I think it may be, then it probably is anchored top and bottom only with a pair of angle brackets screwed to the box frame and the roof deck, and slightly up off the roof deck at that. So it doesn't need to touch the roof deck in the middle area, or anywhere else for that matter. The interior is probably sheetrock slipped up into the groove provided on the edge of the box frame, and that wouldn't be affected by any void either. It could be that the installer, cut and fit a triangle wedge to fill the void under the sides, simply to act as a backer to the step flashing, or possibly not. Again, how long have they been in place already would be suggestive of how well they have performed up to this point. Did they get installed with the last re-roofing job would be my question? or as a separate install.

[Michael D. Thomas]

Thanks for the comments. I'll confine myself to my generic skylight comments.

BTW, what IS the name for this style of roof slope transition?

[Steven Taylor]

I know that a Mansard roof has the curve that your talking about. It's sort of concave.

[John Nosworthy]

Mike,
No fancy roof terminology here. It's a sloped roof terminating in a shallower slope. I can't see the entire roof shape but it would probably best described simply as a gable roof with a "kicker" at the bearing wall. Period.

Steve,
There are a lot of mansard roofs in Brooklyn and they don't look anything like this. Mansards are very very steep, almost vertical, usually concealing a very low slope, or flat roof system within. Think 26" of rise in only 12" of run, or even steeper!

[Barry Adair]

Two terms that come to mind are pagoda and shed extension (colloquial).

The latter is used when the plane of the rafters will leave an over extended, at or below window or door headers, or little or no soffit, the addition of framing members at a lesser slope, as in this example, will allow for a wider soffit and not encroach upon the fenestrations.

[Steven Taylor]

There are not a lot of those roofs in Brooklyn. From the picture above, it looks like a possibility. You are right about the flat roof on top. Are you looking at a different picture then me that shows more of the roof?