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Formula used
boxes = ⌈m² including allowance ÷ (m² per tile × tiles per box)⌉02
Worked example
For 20 m², a 10% allowance and four 60 × 60 cm tiles per box, each box covers 1.44 m². The order is 16 boxes: 64 tiles and 23.04 m² supplied.
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Common mistakes
- Using a nominal catalogue coverage without checking the box label.
- Rounding a fraction of a box down.
- Mixing boxes from different shades or calibres.
- Forgetting a repair reserve when the product may become difficult to source.
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