The worst area is over a full bathroom that doesnt have an exhaust fan or window and theres an attic access hole directly outside the bathroom door.
Roof sheathing buckling.
For other possible causes.
Diagnosing other roof problems.
Spacing and significant changes in moisture.
If the sheathing is not gapped the sheathing itself may buckle especially with thin sheathing 24 in.
Apa recommends a 1 8 inch space between panel edge and end joints.
The pieces of sheathing are supposed to be spaced about 1 8 inch apart so that they have room to expand and contract as the temperature changes.
If the wood structural panels are tightly butted there is no room for expansion and buckling can occur.
Plywood and osb roof sheathing are the most popular roof sheathing materials in the u s.
Asphalt shingles sometimes buckle slightly and in an irregular pattern due to moisture in a the materials of a new roofing system.
The wetness gets absorbed by the felt underlayment causing the felt to wrinkle.
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A broken sagging rafter will also cause a dip in the roof s surface.
But they must be installed correctly.
Also h clips reduce any buckling of those edges over time so they are a good idea even if not always required.
But the moisture evaporates as the materials reach equilibrium with the the surrounding air and the shingles settle back down flat.
Under your shingles there is a layer called the roof sheathing.
This then telegraphs to the shingles above.
For a good reason.
The boards dont appear to have come loose at the nails but instead have cuped badly 1 1 2 2 in places.
This sheathing is generally made from plywood or a similar material.
Any ideas what might cause severe buckling of roof sheathing.
Buckling shingles can sometimes be traced back to mistakes made during roof installation even though the buckling may not show up for a year or two after you get a new roof.
That can mean costly time consuming callbacks.
But if your roof surface is sagging between trusses lack of h clips is only one potential culprit.
Plywood and oriented strand board osb like all wood products will expand or shrink slightly with changes in moisture content.
The nails slip out of the sheathing and create small visible bumps on the surface of your roof.
Visit our blog post why is my roof sheathing sagging between the trusses.
When plywood or osb sheathing picks up moisture it expands.
They are easy to work with readily available and perform the job well.
This house dates back to the 60 s with 3 4 1x8 pine decking.