Shingles

**Tom Rees** · 09-11-2012, 06:34 PM

From my inspection today. The shingles on this mansard roof were separating. You can see in pictures that it appears the architectural shingles are two piece and are separating. Wherever you see the nails the two sections have come apart and the top layer has fallen off. I have never seen this and was thinking either they were not designed for this steep of a pitch (weight was pulling them down) or they were nailed improperly. I would appreciate any thoughts on this. It's obvious that it's wrong and I recommended a roofing contractor repair or replace but am curious why this is happening. The roof also appears fairly new.

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**Jerry Peck** · 09-11-2012, 07:12 PM

Originally Posted by Tom Rees

From my inspection today. The shingles on this mansard roof were separating. You can see in pictures that it appears the architectural shingles are two piece and are separating. Wherever you see the nails the two sections have come apart and the top layer has fallen off. I have never seen this and was thinking either they were not designed for this steep of a pitch (weight was pulling them down) or they were nailed improperly. I would appreciate any thoughts on this. It's obvious that it's wrong and I recommended a roofing contractor repair or replace but am curious why this is happening. The roof also appears fairly new.

Tom,

That is an all to common, and all too unnecessary, condition.

It is so common that the manufacturers, on every bundle of shingles, includes a special drawing and section showing what needs to be done to address that and keep that from happening.

The nails are placed too high.

The different brands of shingles have different spaced lines through which the nails are allowed to be placed. At least one brand has 3 lines - on a slope up to 7:12 (as I recall) the nails may be placed anywhere vertically between the top and bottom lines, however, on steep slopes or high wind conditions (or both as we have both conditions here), the nails MUST be placed only between the bottom line and the intermediate line immediately above it (about 1/2" or so above the bottom line).

The reason for nailing within that narrow nailing band is to make sure the nails penetrate through the glued on tab (the ones that fell out in your photos). If you nail above that intermediate line, the nail does not go through BOTH layers of the shingle and that glued on layer will fall out.

Other manufacturers only provide the narrow nailing lines, that keeps the roofer nailing through both layers all the time, not just on steep roofs or for high wind conditions. While that makes sense, the other manufacturer(s) who use the higher nailing line do not seem to 'get it'. After all, all they do is send someone out to look at the shingle installation and nailing and proclaim "installation error" and "not our problem, call your roofer".

**Tom Rees** · 09-11-2012, 07:28 PM

Thanks Jerry, I thought it had something to do with the nailing pattern.

**BridgeMan** · 09-11-2012, 08:54 PM

There appear to be a few other installation faults contributing to the loss of shingles. Most (all?) shingle manufacturers require that hand-sealing be done on steep roof applications (including gambrel roofs), because gravity alone isn't enough to draw the shingle down tightly against the sealing tabs when they melt. I remember GAF-Elk requiring it for anything steeper than 21:12, while a few others may be a bit less. A typical gambrel roof slope is often 40:12 or greater. I see no signs of hand-dabbing (usually a quarter-sized glob) of any sealant on the photo showing the underside of the broken-off shingle. Also, there don't appear to be enough nails, although can't tell for sure from the limited views of exposed nails. Most shingle manufacturers require more nails per tab (up to 6 instead of the usual 4) on steep roofs to resist the forces of gravity wanting to separate the shingle from the roof.

**Aaron Miller** · 09-12-2012, 02:55 AM

Like this:

**Jerry Peck** · 09-12-2012, 10:43 AM

Originally Posted by Aaron Miller

Like this:

No, like this: http://www.certainteed.com/resources...kTLInstall.pdf

Detail in circle in middle of page, left side, on page 114 (the second page in the attached file)

**Aaron Miller** · 09-12-2012, 10:47 AM

Originally Posted by Jerry Peck

No, like this: http://www.certainteed.com/resources...kTLInstall.pdf

Detail in circle in middle of page, left side, on page 114 (the second page in the attached file)

Got something in your eye(s) JP? My response was to BM's reference to GAF/Elk and not Certainteed. If it's sparring you want, wait on HG to chime in.

**Jerry Peck** · 09-12-2012, 10:55 AM

Originally Posted by Aaron Miller

Got something in your eye(s) JP? My response was to BM's reference to GAF/Elk and not Certainteed.

Aaron,

Nothing in my eye, just something missing in your post ... such as any reference to whom you were replying to.

**H.G. Watson, Sr.** · 09-12-2012, 11:24 AM

You can add gross overexposure, such as is evidenced in the middle picture (top, left) several courses, to the list of problems. At at least one area of suspected impact/ladder damage (lower-middle-left) in same, questionable stagger pattern (middle, right), and (would like to see a winter-time picture)...suspected drainage problems from above (third picture) i.e. frost-thaw/ice damm/icecycle formation and ice shed break-tear off "issues" from top above.

**BridgeMan** · 09-12-2012, 02:31 PM

How can a single shingle (hey, that rhymes!) question turn into such a pi$$ing contest? Come on guys, let's all lighten up a bit--or as my Chihuahuas often tell me, wag more and bark less.