Roof Deck

What Is a Roof Deck

The roof deck is the structural sheathing layer, typically plywood or oriented strand board (OSB), nailed to the top of the roof trusses or rafters to form the flat surface on which the entire roofing system is built. Everything above it, including underlayment, ice and water shield, flashing, and shingles, depends on the deck being structurally sound and flat. A compromised roof deck means a compromised roof, regardless of the condition of the materials on top of it.

Roof Deck Damage and Insurance Claims

Roof deck damage is almost always discovered during tear-off, not during the initial inspection. When shingles and underlayment are removed and the contractor finds rotted, delaminated, or water-damaged decking, the standard process is to document it with photographs, record the number of sheets affected, and submit a supplement. Carriers expect per-sheet documentation with photos showing the damage before the new decking goes on.

Estimating Roof Deck Replacement

In Xactimate, roof deck replacement falls under the RFG category. Specify whether the replacement material is plywood or OSB and the correct thickness (typically 7/16-inch OSB or 1/2-inch plywood for residential). The line item includes removal of the damaged section and installation of the new sheet. On large areas of replacement, factor in additional nailing requirements and any structural sister rafters needed to support the new sheathing.