When my garage was re-roofed, for some reason, one of the nails was not hammered in all the way. It was just slightly raised, but the shingle on top of that nail was slightly raised, allowing wind to get under the shingle. The roofer noticed it, hammered it back in, and we went around and looked at the rest, found another.

So, it's quite possible the problem was a nail that stuck up just far enough for wind to get under one shingle and the rest of your roof is okay.

Do you own a drone? If so (or neighbor's kid has one), I would fly it over the roof and see what else you can see. I don't know anything about proper roof nailing, but I was hosed big time with a condo that had major roofing problems. It is also a very familiar scam. Hopefully, someone on here can give you some good advice. But, in general, do not question yourself for questioning their work.

Pay an independent roofing consultant to do some testing here and there please. Remove some shingles and document the findings and compare them to the manufacturer's installation instructions.

Sigrid,

Funny you should mention the raised shingle. I noticed that my roof has the same problem. I suspect that after tearing off the old roof, they didn't hammer down all of the old nails so they are flush with the decking. I don't know how this can be fixed without removing or damaging the new shingles.

What's under it is roof framing; your underlayment has sagged between the trusses/rafters.

No, that can't be it. The decking looks fine from underneath the rafters.

Nails should be min 1" from the edge of the shingle, looking at your shingle only 2 nails holding a shingle in place, the 2 nails on each edge were placed to close and didn't hold anything, the edges broke right off.

Mike:

Put a straightedge under the rafters/truss and measure to the underlayment please. Looks up close can be decieving.

Architectural shingles weigh about 50% more than 3 tab shingles, too, so that added weight can exacerbate sways in the roof decking.

Just saw the updated picture, it looks like out-lookers were installed wrong, over-spanned and as @ Joseph Corlett, LLC said underlayment sagged. I would have someone investigate the cause of that situation from the attic before roof failure and most likely that area will have to be re-framed.

Just to be sure, is there a gap in your existing shingles so you know for sure that shingle is one of the replacements and not one they tore off but didn't get in the dumpster?

John 9a - the gap left by the shingle that blew off was replaced and they said that they installed it properly, better than the original one was installed.

Joseph Corlett, LLC and GN Builders, the decking is plywood and is flat and in good shape. So the underlayment could not have sagged.

If there is no sag perhaps the rafter is bowed and wasn't crowned. Take a look from the attic and see what's going on there.

For anyone following this thread, the roofer came out and took a look. The waviness near the edge of the roof was due to their use of ship lap to replace the outer 2 feet of decking with was partially rotted. The ship lap is thinner than the 3/4” decking causing it not to be perfectly flat. This is fine, since it isn’t visible unless viewing it from the side of the house.

That would be quite a bit of shiplap. Shiplap is typically called out as 1x and would measure 11/16" or about a 1/32" off 3/4" plywood so not so sure about that. What did he do or say about the shingles that blew off?

I read that shiplap is commonly 1/2” thick. That would mean it could be 1/4” thinner than 3/4” plywood. They obviously cheaper out on this, but I don’t think it’s a fatal flaw that weakens the roof overall. Re the blown-off shingle, it was at the very top of a gable and he thinks it was one-off nailing mistake. It has been windy and no other shingles seem to be affected. If this changes, I’ll ask them to check a random selection of other shingles for nailing deficiencies.

The waviness near the edge of the roof was due to their use of ship lap to replace the outer 2 feet of decking with was partially rotted. The ship lap is thinner than the 3/4” decking causing it not to be perfectly flat. This is fine, since it isn’t visible unless viewing it from the side of the house.

You are much more forgiving than I would be. It is not 'fine'. This is sloppy, cheap workmanship and your roofer knows it. If you decide to sell, the home inspector will mark it up. Your neighbors who have to look at it will know it. Just because you won't see it doesn't mean that no one else will see it. Or have it to look at every. day.

To cheap out & undersize the roof decking and then pile on pricey architectural shingles is absolutely ludicrous.

I can't help but think that 'ship lap' they used was sourced from the busted up pine pallets that the shingles were delivered on.

" I read that shiplap is commonly 1/2” thick. That would mean it could be 1/4” thinner than 3/4” plywood. "

Shiplap is not 1/2". I was in the lumber business for 20 plus years. Interior MDF fake shiplap maybe but not anything I would want on my roof. In fact I would not want anything other than plywood.

And I would be willing to bet you there is a bigger issue there than he let on. That is not a 1/4" difference in sheathing thickness. No. Way. In. Hell.

So you would insist that it’s redone? There are two other houses on my street that used the same roofer and he said that those houses have the same “structural” issue (his words). I’m not sure if they even noticed it. Maybe I’ll get their opinions on this.

If a home inspector were to “mark it up” are you’re saying this issue could reduce the sale price or give a buyer more leverage? Would it be a material amount?