GAF describes asphaltic oil staining that can arise from storage conditions and may weather away. Aggressive washing can cause damage instead of improving the roof.
GAF technical bulletin: Asphaltic oil staining on new shingles.
What this means for your roof
GAF describes asphaltic oil staining that can arise from storage conditions and may weather away. Aggressive washing can cause damage instead of improving the roof.
A useful question for your contractor
Ask for photographs and a follow-up plan to distinguish temporary staining from deterioration.
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 revision: February 1, 2021. This is the date of the manufacturer source, not a claim that this website guide existed on that date.
Read GAF: Asphaltic oil staining on new 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.