Rigid / Continuous Insulation Board Count
Rigid continuous-insulation boards (XPS, polyiso, EPS) for an area, with waste and layers: boards = ceil(area x (1 + waste/100) / board area) x layers. A 1,600 sf wall in 4 x 8 boards at 8% waste is 54 boards a layer, so a two-layer continuous-insulation assembly with offset seams is 108 boards; a single layer is 54. The layer count, set by the required continuous-insulation R, is the multiplier; fasteners, plates, and tape are taken off separately. Distinct from spray-foam-board-feet and insulation-batt-coverage.
Formula and source
boards = ceil(area_sf x (1 + waste_pct/100) / board_area_sf) x layers.
Rigid-insulation board-count identity by name (boards per layer from area over board area with waste, times the layers); first-principles arithmetic.
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