Interior paint take-off — walls and ceiling are figured separately
Walls and ceiling are two separate surfaces: Walls = 2 × (L + W) × H − doors − windows; Ceiling = L × W. A standard door deducts 20 sq ft and a window 15 sq ft — you paint the trim, not the slab or the glass. Each surface gets its own paint, sheen, and coats.
What this diagram shows
A one-point-perspective drawing of a room separates the two paintable take-offs. The walls are the four vertical sides, figured as two times the sum of length and width, times the ceiling height, minus the door and window openings, because you paint the trim but not the door slab or the glass. The ceiling is the top surface, figured as length times width, and is painted separately with its own paint, sheen, and coat count. Worked on a 12 by 14 foot room with an 8 foot ceiling, one door, and two windows: the walls are 2 times 26 times 8, or 416, minus 20 for the door and 30 for the two windows, leaving 366 square feet; the ceiling is 12 times 14, or 168 square feet.
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