TAMKO's notice discusses moisture and deck-movement concerns when spray foam changes the attic assembly. It quotes warranty exclusions that include polyurethane foam applied to the underside of decking
TAMKO technical bulletin: Use of Below-Deck Spray Foam Insulation with Asphalt Shingles.
What this means for your roof
TAMKO’s notice discusses moisture and deck-movement concerns when spray foam changes the attic assembly. It quotes warranty exclusions that include polyurethane foam applied to the underside of decking. This differs from some other manufacturers’ guidance, so a blanket statement that spray foam never affects shingle coverage is unreliable.
A useful question for your contractor
Ask TAMKO to confirm the current warranty terms for the exact proposed assembly before adding below-deck foam.
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: August 28, 2019. The date shown identifies the manufacturer document used for this summary.
Read TAMKO: Use of Below-Deck Spray Foam Insulation with 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.