shingle edge uplift - concern? cause?

[Kristi Silber]

I searched for other threads about this. Undoubtedly they're out there, but I couldn't find them...sorry if I'm repeating what others have asked.

I'm wondering how much of a concern it is when the edges of a few 3-tab shingles here and there are a bit lifted. It seems extremely common; it's rare indeed that I see a roof that's perfectly flat. Typically it's the middle of the tab, or the whole edge is slightly higher (not just the corner), and there aren't any other signs of deterioration. Would this be a sign of aging, poor installation, uneven surface below the shingles, manufacturing defect, or..? My guess based on the position is a slightly high nail, but could it be the beginnings of buckling?

The only immediate danger I can see is a greater probability of wind damage.

The photos are from 3 different roofs. Keep in mind that I don't get on the roofs to do closer inspection (not part of my job). The third one looks most problematic to me - it's beginning to lift at the corners and generally looks less even and more worn.

What think you?

Thanks kindly for your comments!

[Rick Cantrell]

Check for a roof nail under the lifted tab.
Nail was underdriven or backed out (short).
Can also be caused by the tab being slightly bent when laid, forming a tent.

[wayne soper]

Extruding nails caused by temperature differential, poor installation, or subgrade underlayment, will eventually push through the shingle and cause leaks. Resetting is easy, but should be done asap to prevent damage. Most roofs will have a few here and there.

[William Cline]

Protruding nails would be my first assumption, also. Till I got on the roof and checked. Could be tenting. Also could be insufficient edge spacing causing a lift in warm weather which disappears when cold. Have a roofer check it out.

[John Kogel]

Protruding nails would be my first assumption, also. Till I got on the roof and checked. Could be tenting. Also could be insufficient edge spacing causing a lift in warm weather which disappears when cold. Have a roofer check it out.If you slip a thin screwdriver into that tent, it will hit a nail.

The airgun bounced a bit and he let it go, because he's not packing a hammer. Maybe the nail hit a truss chord and the setting on the gun was out of whack.

I think they never saw underdriven nails when men were men with hammers. ;)

[keithsines]

This is an easy one. Young guys on the roofing crews like to see if they can make the nail guns run like a machine gun shooting as many nails as possible as fast as possible. Of course the nails end up every which way but fully set which means someone has to go back through, lift the shingles and set all the nails. I did see one idiot start to set the nails by hammering on top of the shingle. I told him he now needed to replace the shingle.
Keith

[Jim Hintz]

Usually roofing staples, nails occasionally. They ought to outlaw roofing staples or someone create some with barbs on them so they don't back out.

[Jim Hintz]

If you slip a thin screwdriver into that tent, it will hit a nail.

The airgun bounced a bit and he let it go, because he's not packing a hammer. Maybe the nail hit a truss chord and the setting on the gun was out of whack.

I think they never saw underdriven nails when men were men with hammers. ;) "I think they never saw underdriven nails when men were men with hammers" - Or crooked walls when there was a table saw onsite - thing of the past, everything is done with a circular / skillsaw nowdays, and the wood butchers can't follow a chalk line.. You're lucky if a nail-pounder even knows how to crown a joist or a rafter too. Not much pride in workmanship anymore.

[Kristi Silber]

Excellent! Thanks everyone! Nice to know I was on the right tack...I mean, track, and you've given me some other ideas, too.

Sometimes where the sheathing isn't supported well underneath, on edges, for instance, the bounciness makes it harder to drive the nail in. Maybe that's why some roofs have more on the rakes (though wind could of course do it, too, if the seal isn't good). Even a too-big glob of roof cement or a plastic-headed nail not driven far enough into the underlayment could prevent a shingle from laying perfectly flat. At any rate, it often seems to be an installation error rather than sign of weathering, and that's as I'd surmised.

[Mike Kleisch]

I'm going with nail pops too.

I used to hand nail all my roofs, never had a call back, and the other guys would come in with the 6 shooters and bang the roofs out for less money, and I could not believe what I saw looking at those jobs. Some of those "new" roofs were worse than the roofs they tore off, then thought, what the heck, I'll become an inspector, less headaches... :p

[Michael Chambers]

.....I used to hand nail all my roofs, never had a call back, and the other guys would come in with the 6 shooters and bang the roofs out for less money, and I could not believe what I saw looking at those jobs. Some of those "new" roofs were worse than the roofs they tore off..... :p



Kind of like an inspector who is willing to get on a roof when it's reasonably safe so that he or she can do a better job, instead of staying on the ground because "it's not part of my job", and then having to ask others for answers they could have gotten themselves.

Not trying to pick on Kristi, but I really hate that phrase.

[Kristi Silber]

Kind of like an inspector who is willing to get on a roof when it's reasonably safe so that he or she can do a better job, instead of staying on the ground because "it's not part of my job", and then having to ask others for answers they could have gotten themselves.

Not trying to pick on Kristi, but I really hate that phrase.

It's not part of my job. I do inspections for insurance companies, I don't carry a ladder, it would be a huge waste of my time to get up on every roof. I'm not paid enough for it. In the case the phrase is perfectly suitable, which is why I used it. I said myself that I guessed it was the result of high nails, but thought others may have different ideas and experience, and they did.

[Jerry Peck]

I think they never saw underdriven nails when men were men with hammers. ;)

Or overdriven nails - a bit difficult to 'overdrive' a nail when the hammer head is flush with the surface and the nail is therefore tight to the surface.

I'm guessing that if one lifted the tabs of the shingles which did not have an underdriven nail protruding up and holding the shingle tab up - that the inspector would see: nails driven too high, overdriven, at an angle, placed such that there is a visible arc in the nail pattern allowing one to fairly accurately figure out where the guy with the nail gun was standing when he nailed those shingles down.

[Kristi Silber]

I don't know...I think you guys are being a bit hard on roofers with guns. Almost none of the roofs I look at are perfect - each has a few shingles that don't lie absolutely flat. But think of all the nails in a roof! Even a hand-hammered roof can have errors. There are numerous reasons a nail might be a bit high, or at an angle. The layers below the shingles are far from uniform, especially on older homes that have had multiple roofs installed, even if they've been torn off before the current shingles were applied. A nail that happens to go between two sheets of sheathing and into a rafter may not be obviously wrong when it goes in, but work itself out over time. A nail that hits another nail could be bent below the shingles, and go unnoticed.

Power nailers are so much faster, and the quality of the nailing is not necessarily any worse than hand-nailing, it makes no sense to hammer on a roof these days. Used correctly, they shoot a nail straight at a set depth, while the human arm is prone to tiring, and is itself not infallible. That doesn't mean, of course, that roofers shouldn't carry hammers to correct problems. The real issue is doing the best job one can, then noticing and correcting errors, whether from a gun or hammer.