Bubbling Roof - Horizontal Bubbling


Hello. I am a homeowner with a 7 year old composite shingle roof (new construction) that now has a strange bubbling problem. The bubbles seem to run in a horizontal fashion.

Do you think this problem might represent an issue with the roofing product, a problem with the installation, or a deeper problem with the plywood boards? Would my next step be getting a roofing contractor out to the house?

Thank you very much for your help and opinion.


Those humps are very unusual. Would need to see some closer pics to have a better idea what’s going on. When did they start to appear?


There were a few minor, much less noticeable humps last year. However, over the past few months the problem is much more visible and diffuse.

I can try posting a closer picture tomorrow.

Thank you again!


Appears to be a roofing product i have never installed before.

Very unusal looking shingle!!

Composite shingle roof…aaahhhh
Exactly why i am afraid to try them.
Anyone want to identify the brand???


You have a great looking home, other than the shingles anyways… love the rounded porch roof. Anyways, I’ve seen simular looking issue recently. Turned out to be spaced decking (should have been Re decked but previous roofer ignored). A few courses of shingles the nails went between boards, after a crazy wind event the roof looked like yours. The adjuster thinks that the force of wind into large gable end vents basically inflated the roof and pushed shingles outward. Not sure I really belive that, but he covered the entire roof replacement so I wasn’t going to argue.


Can you check it out from the attic? See if they are the horizontal joints of the plywood popping up. I don’t think the roofing material alone would behave like that.


I think The Plastic material (composite) is warping,
Losing its shape.
Yes , it is doing it mostly at the sheeting seams.
But in other places also.
Notice how the bottom 2 rows are flat.
But one shingle on the third row on the bottom left corner area is going crazy.


The spacing looks right for the sheathing to be warped.


Oh , now i see,
I was wrong
It is mostly the decking period and possibly some nail pops.
Every where there is a seam or a dip in the decking or nail pops the material just doesnt want to move with it and absorb into its new shape.
This material just cant curve itself over humps.
It also has a high profile, so when the sun shines at that angle, its shadows will show all its imperfections.


I’ve seen plywood do this but it was within a year of installation.


Thank you everyone for your input a few weeks ago regarding our roof.

Since my earlier post, the roofing contractor who had installed the room came out to assess the situation.

It appears the north side of the roof has moldy/warped plywood. I’ll attach a photo below.

At this point, the contractor is pointing to a ventilation problem leading to too much condensation/moisture build-up. The south side of the roof has many vents and according to their thoughts it should be enough ventilation for the attic space. A few years back when we purchased the home, a city inspector visited and thought that our attic ventilation would be adequate too. Nonetheless, we have a bubbly roof and warped plywood.

Now the the contractor is proposing sealing all the events and using a powered ventilation fan. Would you think this might fix the moisture problem?

I’m willing to replace the roof and moldy/warped plywood but I would hate for this problem to recur again in a few years. As is the house is only 7 years old.

Thank you again for your help.


It looks to me as if your blown in insulation is covering any “intake” (if you have any). They must be free from obstruction for your ventilation system to work to its full potential. (My phone doesn’t have the best resolution though so other roofers please correct me if I’m wrong). Other possible cause would be dryer vent (or similar) leaking moisture through bad connection into the attic.


If the ventilation is working good on the back, I would replace the bad wood and replicate the ventilation on the front. Not a fan of power vents.


Those baffles look crushed. Plywood are best, for that very reason. No matter how heavy handed the spray guys are they won’t crush