Owens Corning's California valley guidance specifies slope limits, bleeder-shingle layout, offsets and a fastener-free area near the centerline. These details differ from other manufacturers' methods.
Owens Corning technical bulletin: California Valley Technical Bulletin.
What this means for your roof
Owens Corning’s California valley guidance specifies slope limits, bleeder-shingle layout, offsets and a fastener-free area near the centerline. These details differ from other manufacturers’ methods.
A useful question for your contractor
Ask for the Owens Corning detail that applies to your roof pitch and shingle.
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: April 3, 2020. The bulletin header is April 3, 2020; the supplied PDF edition was printed in August 2023.
Read Owens Corning: California Valley Technical Bulletin
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.