Plain Facts About Buckled Shingles

Buckling can be defined as the distortion of asphalt shingles due to the movement of the roof deck on which they are applied.

Changes in moisture content typically cause movement of a wood deck.  Increases in moisture retention cause linear expansion, while decreases in moisture retention cause linear shrinkage.  For example, if decking materials are too dry upon delivery, they tend to expand in post-application service, due to water loss.  Slight changes in deck dimensions will force changes in shingle position, due to the simultaneous movement of the shingle fasteners with the deck.  Buckling results when extreme changes in the deck dimensions occur.

Prevention

Use only wood decking materials that have been properly conditioned to be at moisture equilibrium with the job site environment.  These materials should also be roofing manufacturer approved.

Do not expose decking materials to water either before or after application.

Cover wood deck materials with asphalt-saturated felt shingle underlayment, then apply shingles.

Ensure adequate attic ventilation (e.g., a minimum of one square foot net free area per 150 square feet of attic floor space)

Apply shingles in accordance with shingle manufacturers' recommendations.

Correction

Ventilate the attic space to eliminate excess moisture.  The addition of exhaust fans may be necessary.

When buckling persists, remove the fasteners of the affected shingles and refasten.  It may be desirable to replace all distored shingles as well.