Roof Step-Flashing Piece Count

One piece is woven into EACH shingle course as the roof rises along the wall, plus one to start, so pieces = ceil(sloped wall run x 12 / shingle exposure) + 1. A 20 ft run against a wall at a 5 in exposure takes ceil(240/5) + 1 = 49 pieces; a longer exposure means fewer courses and fewer pieces. Order a few extra for waste. Each L-shaped piece laps the one below by the exposure and tucks under the siding/counterflashing -- step flashing is woven course-by-course, NOT a single continuous strip (a leak-prone mistake). A takeoff estimate; the shingle exposure, the flashing size, and IRC R905.2.8.3 and the manufacturer's details govern the install.

step_flashing_pieces = ceil(wall_run_ft x 12 / shingle_exposure_in) + 1; order_pieces = ceil(step_flashing_pieces x (1 + waste_pct/100)).

Roof step-flashing piece-count takeoff (one piece per shingle course) by name; IRC R905.2.8.3 and the shingle / flashing manufacturer's details govern the install.

The piece count is public first-principles (one flashing per course plus one); the sloped wall run and the shingle exposure are the field measurements.

Estimate. AHJ and licensed professional govern.

Field names used by the API: wall_run_ft, shingle_exposure_in, waste_pct, step_flashing_pieces, order_pieces

• One piece per course pieces = ceil(wall run x 12 / shingle exposure) + 1; woven course-by-course, not a continuous striproofing practice / IRC R905.2.8.3
• Exposure and size standard ~5 in shingle exposure; order extra for waste; the flashing size and manufacturer details govern the installshingle / flashing manufacturer