Find the line that covers the wood below the shingles

Roof decking is the surface the roofing system attaches to. A contractor may be able to spot some damage from the attic, but additional areas can become visible only after the old covering comes off. Find the words “decking,” “sheathing” or “plywood” in your estimate. Ask which material and thickness the quoted price covers and how the crew will document any extra work.

Work through a six-sheet example

Suppose a proposal includes two sheets and quotes $90 for each additional installed sheet. If the crew documents six sheets replaced, four are extra. Four times $90 adds $360 to the base price, assuming those are the agreed terms. These numbers illustrate the calculation. Your local rate, included quantity and scope belong on your own estimate.

6 sheets replaced

Count documented by the crew.

− 2 sheets included

The base price already covers these.

= 4 extra × $90

The added decking charge in this example is $360.

Make two bids comparable

One contractor may include several sheets in the base bid. Another may charge from the first sheet. Ask both to price the same hypothetical quantity and include labor, fasteners, removal and disposal as applicable. Confirm how partial sheets or plank decking would be counted. A per-sheet rate alone cannot tell you which overall proposal costs less.

Agree on a decision while the roof is open

Before work starts, give the contractor a number where you can be reached during tear-off. Ask for a marked photo of the affected area, the quantity and the added amount before authorizing the change. Keep the approval with the final invoice so you can match the charge to the work. If the contractor finds framing damage, ask for a separate description and scope.

For more detail, see a roofing contractor’s explanation of tear-off and per-sheet pricing. Related reading: what to put in a written change order.