Waste is project-specific
Waste is not a universal 10%. It depends on material format, layout, installer experience, breakage risk, pattern, stock sizes and whether offcuts can be reused.
Cutting waste
Sheet goods, flooring, decking and tiles create offcuts. A layout that aligns well with stock dimensions can reduce waste dramatically.
Breakage and defects
Bricks, tiles, slabs and boards may arrive damaged or become damaged during handling. A small reserve can avoid delays and batch mismatch.
Irregular geometry
Curves, diagonals, hips, valleys and many openings generally increase waste compared with simple rectangles.
Contingency vs deliberate over-ordering
A contingency should reflect uncertainty. For expensive or returnable materials, model the exact layout first and then choose a smaller rational allowance rather than automatically adding a large percentage.
Document your assumption
BuildCalc supports the United Kingdom, United States, Canada, Australia, New Zealand, Ireland and South Africa. The geometry is universal, but terminology, units, pack sizes and common product dimensions differ. Use the dimensions printed on the product you intend to buy rather than assuming a regional default is exact.
BuildCalc displays waste as a separate input where practical so the assumption is visible. Record the percentage used and why, especially in Trade Mode estimates.
Use the related calculators
Use the calculator for your measurements, then return to this guide to check assumptions, allowances and ordering considerations.
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