What are these ripples on roof

I found these ripples on the roof line and can not figure out what would have caused them.
Anyone have any ideas or seem this before?

They were about every 8 ft along the roof line on the one side of the house. 3 yr old hip roof. They were right at the edge above the soffit area and just a couple of feet long.
I could see nothing from the attic as the insulation baffles covered the area in all cases.
The attic had H clips although the lack of them should not cause a ripple on an angle.

I would say from the attic roof structure, see it all the time.
Usually the ventilation, insulation, exhaust systems and attic conditions affect the underlying roof structure.

What did the attic look like, H clips or proper spacing between roof decking? (HELPS IF I READ YOUR POST)

Not a big deal unless the shingles come off.

David…I did not write it up but was curious. If the ripples had of been in a straight vertical line I would have guessed something with the sheathing installation, but these ripples are on an angle. The attic looked good in most respects although the different types of trusses they used for a simple hip roof was unusual. Either way, the area in question was all one kind of truss and the opposite hip side had no ripples

I don’t know what has caused the ripples, I do know that I wouldn’t ignore it as it is not right. Further eval and correction from a licensed roofer…

Heavy weight felt paper installed with ripples in it will reflect in the shingles over time…

Doesn’t look like they are on an angle to me…looks vertical, which would indicate a plywood end seam buckling up.


Those are usually (but not always) caused by tarpaper getting wet, shingled and then the gas from evaporation causes the buckles.

…about every eight (8) feet is your guide as to what’s wrong here. The roof sheathing is run horizontally on eight (8.’) centers. The nails are failing on the seams and the butt joints are lifting. I suspect it’s only on one side that it’s failing rather than both pieces of plywood lifting at the seams where it’s nailed to the truss. Screw through the comp roofing material into a sistered block that’s added the truss or rafter…
Next reroof should solve any visual effects of the wet patch over the 10 year comp roof .

No doubt in my mind…that is an end seam buckle of the plywood sheathing. Shingling over damp loose felt paper does not look like that. It is a very defined **vertical **buckle…look at the cutouts on the 3-tab shingles.

Thanks Rick and Bradley…That picture and that side of the roof appear to be a bit of an illusion compared to other roof pictures of the house I have. You are right; follow the shingle line and it is a vertical ripple (not angled as I thought). Add in the every 8 foot ripple and yep, that would be the sheathing seam buckling.
Mystery solved. Lesson ; don’t let roof material illusions fool ya.

I had something similar but it went most of the way up the roof surface.

So, that’s where that hammer is…

Looks like they railroaded the decking for sure…

I agree it looks more like expansion due to mo9strure absorption at a sheathing joint, but it is more pronounced at the bottom. That type of buckling is uniform when it’s the result of excessively dry sheathing panels being installed butted, then later expanding.
Here, buckling is more pronounced toward the eve, indicating that the source of moisture is at the eve.

could it be trusses offset on kenneths picture and maybe truss tails added on but not nailed flush on ricks picture ??? although the roof sheething would float over the framing and hide the imperfections

On offset truss would leave a ridge all the way to the peak, and a trough on the opposite slope.

Definitely decking joint, loose or buckled.