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How to measure a building?

Decide first why you are measuring the building, because the purpose sets which areas count and where the tape goes. For a residential gross living area figure, sketch the exterior, measure each level along the outside finished wall surface with a laser or tape, break the footprint into rectangles, multiply length by width, and add the pieces.

Common purposes include appraisal reporting, flooring, renovation planning, permitting, insurance, and construction estimating. The rough exterior sketch should show the building shape, bump-outs, garage, porches, and floor levels before any numbers go on it.

Record each rectangle's length and width on the sketch as you go. Measure above-grade and below-grade levels separately. On a two-story home, calculate each floor on its own instead of assuming the upper level matches the lower footprint.

Ceiling-height changes, unfinished areas, garages, open stairwells, decks, and covered porches get documented separately. Residential appraisal work commonly follows ANSI-based methods, which rely on exterior measurements and keep above-grade living area distinct from below-grade finished area.

Take photos, keep the dimensioned sketch, and check the arithmetic before reporting the final figure.