Thread: Test for the Roofers

What is the defect in this roofing surface? What is the cause?

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Maybe this is a better picture.

Originally Posted by A.D. Miller

What is the defect in this roofing surface? What is the cause?

You mean that line running across the roof at that course line?

Have no idea what the defect is.

Almost looks like the shingles were doubled up there, or there was a difference in the roof sheathing being out-of-plane with that below?

Originally Posted by Jerry Peck

You mean that line running across the roof at that course line?

Have no idea what the defect is.

Almost looks like the shingles were doubled up there, of there was a difference in the roof sheathing being out-of-plane with that below?

JP: I really have to give them a chance, let's say until 3:00 CST. Then I will reveal all . . . just a figure of speech . . .

Still waiting for Bob "Hot Foot" Harper to run out of bullets, hobble on over here and answer this question. About 4 minutes left now.

Originally Posted by Jerry Peck

You mean that line running across the roof at that course line?

Have no idea what the defect is.

Almost looks like the shingles were doubled up there, or there was a difference in the roof sheathing being out-of-plane with that below?

JP: OK, they've had plenty of time.

New(mark) house in Dallas. The framers did not stager the roof sheathing on that slope, and to boot, also did not install h-clips, but only along that section where they did not stagger the panels. Unbelievable!

Originally Posted by A.D. Miller

JP: OK, they've had plenty of time.

New(mark) house in Dallas. The framers did not stager the roof sheathing on that slope, and to boot, also did not install h-clips, but only along that section where they did not stagger the panels. Unbelievable!

Aaron,

Okay, I'm at a loss here ... how does not staggering the roof sheathing create that line?

I do not understand the answer. What occurred because the joints were not staggered. And did it simultaneously happen across the whole width of the roof?

AD, got on too late tto post but that would have been my first guess although I would ahve a hard time believeing they could be so stupid. Did I just say that.
Could you see that joint all the way down at the soffitt area in the attic?
Oh and a stager is a Broker who furnishes someone elses house in order to hide what a piece of crap it really is.
A stagger is what happens when we leave the bar too late and what dosen't happen when we wake up too early and try to install roof sheathing on a new home.
Still a nice piece of work that any non green card holder would be proud of.

Can someone explain to me how not staggering the roof sheathing can/will cause that?

I can see that line if ... the sheathing above the line is thicker than the sheathing below the line, that would account for the out-of-plane look, ... but not staggering the roof sheathing ... ?????

I need some help to understand that.

I've always thought that to be from setting a course of shingles slightly high or low and getting a slight elevation on the course. I suppose it could be from the sheathing but I routinely see all the seams line up and I don't see that happening.

Originally Posted by Matt Fellman

I suppose it could be from the sheathing but I routinely see all the seams line up and I don't see that happening.

???

Matt,

You see all the long horizontal edges (seams) line up? That is good.

You see all the short vertical edges line up? That is *not* good.

By the way, you should not be seeing the short vertical edges anyway as they should be on top of the truss top chord or on top of the rafter. One can frequently tell where the panels end by the face grain changing, but the vertical short edges should not be visible.

Long edges.... the ones in line with the AD's picture. There are often those metal clips in place at the mid-point between the trusses/rafters.

I would say that the upper course of shingles lines up with the lower course as in no stagger. If the hole roof wall taller then I would have another guess.

I've come to the party late, but would have been wrong anyway's. I have seen that line caused by roofers stopping work for the day, and lapping 30# felt over the section where they stopped . The next morning they get lazy, and just roof right over the felt which is now sandwiched between 2 layers of comp. Problem is that the shingles can't seal down as a result.

I have seen this before and agree with Brandon's assessment. I also agree with Jerry that the horizontal joints in plywood sheathing are not staggered.
The missing H-clips would allow the sheathing to be wavy (up or down) in between the trusses. The sheathing will possibly start to buckle along the horizontal seam of the missing clips due to improper spacing. This would happen if there is not 1/8" gap as recommended by the APA and plywood manufacturers, due to expansion and contraction of the plywood. The H-clips are designed to maintain this spacing.
Jim

You guys must see a lot of cheap, thin, roof sheathing as where I came from we always used roof sheathing thick enough that no edge supports were required.

'H' clips? What are they?

They are for pansies who cannot carry the weight of real roof sheathing and try to get by with using paper for roof sheathing, which then needs additional supporting.

I doubt that the lack of using 'H' clips allowed/caused that as typically when one span of thin roof sheathing between trusses expands and bows upward the adjacent span of that paper will expand and bow downward, and that photo shows the line raised along the entire length of the roof.

I've never seen what Brandon described done (that would require laying the shingles down course by course from the bottom up instead of laying them up in step fashion), but, if done, I can see that creating a horizontal line as in the photo.

But so would installing 7/16" or 1/2" roof sheathing up to that line and then installing 5/8" or 3/4" roof sheathing from there up.

[quote=Jerry Peck;83302]You guys must see a lot of cheap, thin, roof sheathing as where I came from we always used roof sheathing thick enough that no edge supports were required.

'H' clips? What are they?

They are for pansies who cannot carry the weight of real roof sheathing and try to get by with using paper for roof sheathing, which then needs additional supporting.


Not all of us live in hurricane zones Jerry.

Originally Posted by K Robertson

Not all of us live in hurricane zones Jerry.

You did notice my smiley faces, right?

I tweaked the photo. I say that line was cause by...

A) Luigi did the job up until that line, then he had to go home sick so his brother Mario took over, but set his first course a little different than what Luigi was using.

B) They opened a new bundle of shingles right there that were stored on edge in the sun which flattened them a little on the edge.

C) The sheathing is slightly delaminated at the edge because the the plastic wrapping on the bundle came loose on the train car from the mill.

D) It's not a defect at all. It was added in Photoshop just to confuse us.

As far as varying the thickness of the sheathing...Come on who's gonna do that. I mean really.

Do some of you actually stagger the horizontal edges of the plywood when decking a roof? I've never seen that done. We stagger the 48" edges, but I have yet to see anyone do it on the 96" side. Trying to stagger both seems like it would be pretty much of a CF on the roof.

A.D., is this a trussed roof? The reason I ask is that the line appears to line up with the location where a hinge would be in a hinged truss. If the two sectios of the truss on opposite sides of the hinge don't line up quite right, that could account for the line (the roof sheathing above the line is slightly higher that the sheathing below it).

Just a thought

I see this sometimes on modular construction (although this house doesn't look like a typical modular home). The roof is constructed in the factory, pre-shingled with a hinge to allow the roof to be folded for transport. The upper shingles or shingles at the hinge are then installed after the roof is unfolded and installed on the modules.

ad,
staggering the plywood sheeting may not be required unless you require high shear values for diaphragms. h clips may not be required depending on the snow loads, spacing of supports,thickness and span ratings of the plywood etc. check with the apa website next time !

Originally Posted by Mike Truss Guy

As far as varying the thickness of the sheathing...Come on who's gonna do that. I mean really.

I always looked at the labeling on the roof sheathing, needed to be 19/32 inch (5/8 inch).

Years ago down in South Florida some places allowed 15/32 inch (1/2 inch) under asphalt shingles, then along came Hurricane Andrew in 1992 and all the roof sheathing went to 19/32 inch as I recall.