Estimating and Planning
Estimating and Planning tests takeoff math, roof geometry, waste, material quantities, labor, and job sequencing. The exam expects you to convert a plan-view footprint into roof area and order enough material without inflating the bid.
Takeoff and math
- Measure the footprint and roof lines: eaves, rakes, ridges, hips, valleys, and penetrations.
- Convert slope to a pitch multiplier: multiplier = √(1 + (rise/run)²), with run expressed as 12. A 6:12 roof has a 1.118 multiplier; an 8:12 roof has 1.202.
- One roofing square equals 100 square feet of roof surface, not footprint.
- Add waste: about 10% for simple gable roofs, 12–15% for hips, valleys, and cut-up roofs. Order starter, ridge cap, underlayment, ice barrier, drip edge, and fasteners by linear feet or roll coverage.
- Build a labor plan for tear-off, deck repair, dry-in, and final; include dumpster, permit, and weather days.
Worked example
A hip roof has a 2,400-square-foot footprint and 8:12 slope. Roof area = 2,400 × 1.202 = 2,885 square feet = 28.85 squares. Add 12% waste: 28.85 × 1.12 = 32.3, so order 33 squares. If eaves total 200 linear feet, ice barrier at 3 feet wide covers 600 square feet; at 225 square feet per roll, order 3 rolls. The estimate must also include ridge and hip cap and valley flashing.
Traps
Bidding footprint as roof area; forgetting waste; using the wrong multiplier for the pitch; undercounting valleys and penetrations; missing decking replacement contingency; ordering material before verifying slope and manufacturer coverage.