Gross vs. net wall area for siding — subtracting windows and doors, then adding waste
Size a siding order by net area, not the whole wall: subtract the windows and doors from the gross wall, then add 10–15% for cuts and coursing.
What this diagram shows
A wall elevation showing how to size a siding order. The whole wall, dimensioned by width and height, is the gross area. The window and the door are cut out and subtracted; the shaded remainder is the net siding area (gross wall minus openings). A separate note shows that a 10 to 15 percent waste factor is then added for cut-off and even coursing. Siding is ordered by net area plus waste, never by the gross wall alone.
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