Install Synthetic Roofing Underlayment

What happens here

After the roof deck is clear, synthetic roofing underlayment is installed. The builder unrolls the blue 'CertainTeed RoofRunner' material across the roof, carefully aligning it. The underlayment is then secured to the plywood roof deck using a hammer and roofing nails. This layer provides a crucial secondary water barrier and helps protect the roof sheathing from moisture penetration.

Goal: Apply a protective, waterproof layer to the roof deck.