How the calculation works
The formulas
Give every section a shared X/Y origin. Overlapping sections are merged before area is measured. Select exposed section sides; only portions on the final outside boundary contribute to edge length. Cutouts must lie inside the union.
Gross area = union(rectangular sections)
Net area = gross union − union(cutouts)
Exposed edge = selected side portions on the final exterior boundary
Assumptions to check
- Only axis-aligned rectangles are modelled; cutout edges are not counted as exposed outer edges.
- Surface quantity is not slab nesting, fabrication pricing, seam placement, or support design.
A worked example
Two overlapping 2 × 0.6 m sections with 1 m overlap have 1.8 m² combined area. A 0.5 × 0.4 m cutout leaves 1.6 m².