Work out roof sheet quantity instantly with clear inputs, formula shown and shareable results.
Profiled sheeting is counted by effective cover width, not by overall width, because one rib overlaps the next. Across the roof the count is length divided by cover width; up the slope each row loses about 200 mm to end lap, so the usable sheet length is reduced before dividing into the rafter length.
Sheets across
Count = ceil(roof length / effective cover width)
Rows
Rows = ceil(rafter length / (sheet length - 0.2 m end lap))
Count = ceil(roof length / effective cover width). Profiled sheeting is counted by effective cover width, not by overall width, because one rib overlaps the next.
It changes the rafter length, which is longer than the plan dimension by the pitch multiplier. Measure or calculate the true slope length rather than the plan projection.
This calculator takes 4 inputs: Roof length along eaves, Rafter length up the slope, Sheet effective cover width, Sheet length. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.