A shingle roof needs a sound, smooth and properly fastened deck. GAF distinguishes approved wood decking from insulation and other materials that cannot serve as the direct fastening base
GAF technical bulletin: Appropriate substrates for GAF asphalt shingles.
What this means for your roof
A shingle roof needs a sound, smooth and properly fastened deck. GAF distinguishes approved wood decking from insulation and other materials that cannot serve as the direct fastening base. Unsupported gaps and deteriorated panels need attention before roofing begins.
A useful question for your contractor
Ask how the deck will be inspected after tear-off and how unsuitable sections will be documented.
Ask for the answer to be tied to the actual roof condition and the exact product being installed. Keep the agreed repair or installation detail with your estimate and project photos.
Bulletin dated: June 26, 2025. The PDF header says June 26, 2025, while its revision footer says June 26, 2026. Both are retained here; the original release date is not confirmed.
Read GAF: Appropriate substrates for GAF asphalt shingles
This homeowner summary explains the cited bulletin. The complete manufacturer document and current product instructions govern the installation details. A requirement for one manufacturer or product should not be transferred to another without checking.