Tiling a bathroom floor with wastage
A homeowner is tiling a rectangular bathroom floor measuring 2.4 m by 1.8 m. The tiles are square, 300 mm on each side, sold in boxes of 12 tiles. Tiles must be cut at the edges, and the tiler advises allowing 10% extra for cuts and breakages. There is also a rectangular shower recess in the corner measuring 900 mm by 900 mm that will NOT be tiled - it gets a prefabricated base instead. The tiles cost $42.50 per box, and adhesive and grout come as a combined kit costing $65, which covers up to 6 m².
1. Calculate the area to be tiled and the number of boxes required, allowing 10% wastage.
Read the worked answer
Floor area: 2.4 × 1.8 = 4.32 m².\nShower recess: 0.9 × 0.9 = 0.81 m² (not tiled).\nArea to tile: 4.32 − 0.81 = 3.51 m².\n\nEach tile: 0.3 × 0.3 = 0.09 m². Tiles needed before waste: 3.51 ÷ 0.09 = 39 exactly.\nWith 10% waste: 39 × 1.1 = 42.9, so 43 tiles.\nBoxes: 43 ÷ 12 = 3.58, so 4 boxes (48 tiles).\n\nNote the judgement point: rounding up to whole boxes already gives spare tiles, but the 10% allowance is still needed because cuts at edges waste partial tiles.
2. Work out the total cost of tiles, adhesive and grout, and state whether one adhesive kit is enough.
Read the worked answer
Tiles: 4 boxes × $42.50 = $170.00.\nAdhesive/grout: one kit covers 6 m², and 3.51 m² is well under that, so one kit at $65 is enough.\nTotal: 170 + 65 = $235.00.\n\nBuying a second kit would be wasted money since coverage (6 m²) exceeds the tiled area (3.51 m²).