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Takeoff Guides

Roofing Takeoff Guide

Short answer

A roofing takeoff measures roof area in squares (100 SF units) after correcting slope measurement for pitch, linear feet of edge metal, flashing, ridge, and valley, plus underlayment and the accessories the system requires.

Roofing is measured in squares — hundred-square-foot units — but the plan view lies: it shows horizontal area, and the roof is sloped. The pitch factor converts plan area to true surface area, and it is the first correction to apply.

Linear items do the rest of the work — edge metal, ridge, valley, flashing, gutters — measured per condition, not per material count.

What to measure

  • Each roof section area — corrected by its pitch factor.
  • Eaves, rakes, ridges, hips, and valleys separately.
  • Wall and counter flashing at every intersection.
  • Penetrations — pipes, vents, skylights, curbs — as EA.
  • Gutters and downspouts.
  • Tear-off area if reroofing — same area, different price line.
Roofing takeoff units
ItemUnitHow measured
Roof coveringSQ (100 SF)Plan area × pitch factor, by roof section
UnderlaymentSQ or rollsSame area, layers where required
Edge metal / drip edgeLFEaves + rakes perimeter
Ridge, hip, valleyLFMeasured on plan or roof plan
Flashing — wall, counter, pipeLF / EAPer condition
Gutters, downspoutsLF / EAPerimeter and drops

The pitch factor is the whole trick

Measuring a sloped roof on the plan gives its shadow. Multiply by the pitch factor — plan area times the secant of the slope — to get surface area. A 6:12 roof carries roughly 12% more material than its plan area; a 12:12 about 41% more.

Sections and scale

Roof plans often sit at a different scale from the floor plans, and enlarged details differ again. Verify the scale on the roof plan itself before measuring — and re-verify on each enlarged condition.

Common mistakes

  • Using plan area straight — no pitch correction.
  • One pitch factor for a roof with multiple slopes.
  • Missing crickets, saddles, and low-slope transitions.
  • Measuring flashing conditions once when the detail repeats around the building.

References

  • Project specifications — roofing section
  • Manufacturer system requirements

Related questions

100 square feet of roof surface — the unit shingles and most coverings are priced and ordered in.

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