Material Quantity
Quantity for common assemblies with waste factor.
Example
You enter
- Assembly drywall_4x8
- Area (ft²) 1000
You get
- Raw units 31.25
- Units (with waste) 35
- Coverage / waste 32
- Waste factor 0.1
Checked against published worked examples from: Inch Calculator (inchcalculator.com).
Details, formula, and sources
Formula or tableUnits = ceil(area / coverage per unit x (1 + waste)).
Source and editionEngineering-practice waste-factor consensus.
Free accessFree in published trade references.
What governsEstimate. AHJ and licensed professional govern.
API field namesassembly, area_ft2, units_raw, units_with_waste, coverage_ft2_per_unit, waste_factor
- Waste factor fixed per assembly (10%; 15% for 3-tab roofing)engineering practice