Roofing looks like the simplest takeoff on the job – measure the area, divide by a hundred, order squares. It is also one of the most commonly under-bid scopes in the business.
Area is not area
Plan area is not roof area. A 6:12 pitch adds roughly twelve percent. Steep or complex roofs also add labor, not just material, and the two do not scale together.
Linear feet drive the details
Ridge, hip, valley, eave, rake and starter all have their own material and their own labor rate. On a cut-up residential roof, the linear items can approach the field material in cost.
Penetrations and flashing
Every pipe, curb, skylight and mechanical unit is a flashing detail with a labor hour attached. Count them off the mechanical plan, not the roof plan.
Tear-off and disposal
Number of existing layers changes both labor and dumpster count. If it is not documented, price one layer and state the assumption.
A roofing takeoff that lists squares by plane and pitch, linear footage by condition, and a penetration count is a bid you can defend. One that says ’42 squares’ is a guess.