Roofers carefully install a black, self-adhesive ice and water shield membrane along the roof’s edge and valleys. The underlayment is being unrolled and pressed firmly onto the plywood decking to create a watertight barrier. This critical step helps protect the roof from water infiltration caused by ice dams and wind-driven rain.

Roofers install synthetic underlayment over OSB roof decking as part of a new roofing system. The underlayment is being rolled out in straight rows, fastened securely with cap nails to ensure durability and water resistance. The crew works methodically, ensuring full coverage and proper overlap between layers to create a secondary barrier against moisture before shingles are applied.