Curling shingles, the main culprit of wavy shingles, is inadequate ventilation, which I discussed here. These buckling shingles are usually noticed in a straight-line pattern, or across the roof in ripples that look like they have air bubbles stuck under them. Although the underlying cause is usually excess moisture under the shingles, there are several factors that add to the severity of wavy shingles, including:
As can be seen, most of the causes of shingle buckling are excess humidity—which needs to be eliminated first by improving attic ventilation by a qualified roofing company. Then, decking needs to be fixed if it is loose or damaged. Finally, shingles can be re-fastened, or replaced if they are warped.
When faced with buckling or wavy shingles make sure to get your roof inspected, as this could be a sign of harmful moisture in your attic which will not only prematurely age your roof, but cause the wood to rot in the rest of your home.