Roof flashing piece estimator

Step Flashing Calculator

Estimate step flashing pieces along a roof-to-wall run from wall length, shingle exposure, number of sidewall runs, waste, and cost. It gives a quick count before matching the roofing system details.

Units

Roof-to-wall run length (ft)Shingle exposure (in)Matching sidewall runs Waste / extras (%)Cost per piece ($)

Flashing pieces

Courses covered

Wall run measured

Rough cost

Flashing details control the final installation

This calculator counts pieces only. Step flashing size, headwall details, kickout flashing, counterflashing, siding clearance, roof pitch, shingle exposure, and local code must match the roofing manufacturer.

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Step flashing formula

Courses per run = ceiling(wall length in inches ÷ shingle exposure)

Pieces = courses per run × sidewall runs × (1 + waste %)

Measured wall run = wall length × sidewall runs

Sample takeoff

A 20 ft sidewall with 5 in shingle exposure, one run, and 10% waste needs about 53 step flashing pieces for 48 courses.A 6 m sidewall with 125 mm shingle exposure, one run, and 10% waste needs about 53 step flashing pieces for 48 courses.

Step Flashing Calculator FAQ

How many step flashing pieces do I need?+

Divide the roof-to-wall run by the shingle exposure to count courses, multiply by sidewall runs, then add waste.Divide the roof-to-wall run by the shingle exposure to count courses, multiply by sidewall runs, then add waste.

Is step flashing based on roof slope?+

The piece count usually follows shingle courses along the sidewall. Roof slope and wall details still affect the correct flashing size and installation.The piece count usually follows shingle courses along the sidewall. Roof slope and wall details still affect the correct flashing size and installation.

Does this include kickout flashing?+

No. Add required kickout flashing, headwall flashing, counterflashing, and manufacturer-specific pieces separately.No. Add required kickout flashing, headwall flashing, counterflashing, and manufacturer-specific pieces separately.