Roof Deck Seams Visible - What's Wrong?

[psullivan]

Saw this yesterday (11/17) on the home I was inspecting, and several other homes around it. Brand new construction. I've seen this sort of thing before, but not this visible nor widespread. The decking is 7/16" OSB with rafters 24" OC. Location is central Texas. My guess is that it rained while the decking was exposed, and the edges all swelled up. OSB swells when it gets wet, but does not subsequently shrink back after it dries. Some of these ridges are 3/4" proud of the surface. Will this prematurely wear the shingles? What is your take on this, and what should be done?

[psullivan]

Oh yeah ... I forgot to mention that H-Clips were properly installed.

[Jeffrey Moore]

How was the attic ventilation and was the decking "bouncy" ?

[psullivan]

Attic ventilation was fine (plenty of soffit & static vents). Deck was solid. This is a brand new home.

[mnahrgang]

I wouldn't buy it like that. I think you are likely correct that the shingles will wear. Also it looks like crap cosmetically. I'd write it up basically saying what you said and let the buyers make their own decisions. Bad move on the roofers part to leave exposed sheathing in a rain storm...

[Doug Edwards, CMI]

Do you have any photos of the swollen edges from inside the attic. A 3/4 inch deflection is pretty significant. I would be surprised if the shingle manufacture's warranty would honor this if in the event the roof fails as it was installed improperly over degraded surface decking material. Also note that the swollen edges over the trusses are the nailing points which when the edges are already damaged (swollen from the water exposure) further weakens the integrity of the roofing structure. Water damaged OSB just comes apart / crumbles when anyone tries to used fasteners on it. Roofer (and the builder) ought to have their heads examined for going ahead and roofing over degraded decking. Just asking for a lawsuit.

[George P. Wells, CMI]

Originally Posted by mnahrgang

I wouldn't buy it like that. I think you are likely correct that the shingles will wear. Also it looks like crap cosmetically. I'd write it up basically saying what you said and let the buyers make their own decisions. Bad move on the roofers part to leave exposed sheathing in a rain storm...

I see this all the time. It is one of my pet peeves. Builders around here (SE MI & NW OH) refuse to cover roofs during construction. They tell homebuyers that this is "normal". I tell my customers that it may be normal for the builder but it still isn't right!

The problems are not only with roof decks. I see a lot of damaged sub-floors too. This is one of the reasons why home inspection is still a growing industry.

[David P. Valley]

Those are definitely swollen edges on that OSB.

The builder should be forced to re-do their work.

[George Russell]

Was those pics taken in the morning? If so go back in the afternoon....betcha can't see them then
G

[Marcel R. Cyr]

If this is new construction, it should point blank not be acceptable for sale until corrected.
No one should have to live with an obvious defect as such.
If the builder gets pinched on this one, next time he will protect the godarn thing properly. Makes all builders look bad.

[Kenton H. Shepard, CMI]

Originally Posted by psullivan

Saw this yesterday (11/17) on the home I was inspecting, and several other homes around it. Brand new construction. I've seen this sort of thing before, but not this visible nor widespread. The decking is 7/16" OSB with rafters 24" OC. Location is central Texas. My guess is that it rained while the decking was exposed, and the edges all swelled up. OSB swells when it gets wet, but does not subsequently shrink back after it dries. Some of these ridges are 3/4" proud of the surface. Will this prematurely wear the shingles? What is your take on this, and what should be done?

That's caused by a significant amount of moisture being absorbed by the sheathing after the shingles were installed. Shingles have buckled at the panel edges as sheathing panels expanded.
It's not really the roofer's fault but the fault of the general contractor or whoever did the scheduling. OSB reacts pretty quickly once it gets rained on. I guess it's possible that the roofer got up there on recently-rained-on sheathing that hadn't yet expanded, but I think it's more likely that the moisture was absorbed from the underside.
This has popped up in researching the roofing course and this photo a great example. In what I've read, they talked about moisture being absorbed for the underside. They never said... but they implied that sheathing panels reacted fairly quickly to being rained on. If it was rain on exposed panels which were then roofed over, it would have to be residual moisture on the surface of the sheathing that got locked in by the roofing materials that would cause enough swelling to buckle shingles 3/4", which is a lot of buckling and reflects a lot of sheathing expansion. That's my 2 cents.

The source... man, it's so dry here in CO that we seldom see this. Maybe closing the home up as drywall mud is drying, especially if the home has recessed lighting left on. That can create quite a bit of stack effect that pull moist air up into the attic. It could be made worse if there'd been recent rain and the air was humid and also if the sheathing was wet when the roofer climbed up there. It can be a combination of things.

[mnahrgang]

Originally Posted by kshepard

That's caused by a significant amount of moisture being absorbed by the sheathing after the shingles were installed. Shingles have buckled at the panel edges.

Kenton...Honest question here....

What makes you say with such conviction, that the moisture was absorbed after the shingles were installed? And if so, what could introduce that much moisture to them?

I'm only asking, because the other explanations presented so far, seem more plausible to me on the surface. I'd like to know what you know on this.

[Kenton H. Shepard, CMI]

Originally Posted by mnahrgang

Kenton...Honest question here....

What makes you say with such conviction, that the moisture was absorbed after the shingles were installed? And if so, what could introduce that much moisture to them?

I'm only asking, because the other explanations presented so far, seem more plausible to me on the surface. I'd like to know what you know on this.

I added to my post below, Mark.

[mnahrgang]

Originally Posted by kshepard

I added to my post below, Mark.

Thanks...

So it got rained on, shingled, then expanded/buckled...

[Joe Funderburk, CMI]

May want to point out that it will come back to haunt the buyer when they decide to sell it.