Question 1

How much waste should I add for tile?

Accepted Answer

10% for standard installations, 15% for diagonal layouts, 20% for complex patterns.

Question 2

How many 12" tiles in a square foot?

Accepted Answer

One. A 12-inch tile covers exactly 1 ft². For a 120 ft² floor with 10% waste, plan for 132 tiles.

Question 3

How much thinset do I need?

Accepted Answer

Roughly one 50-lb bag per 40–60 ft² with a 1/4-inch square-notch trowel. Large-format tile needs a bigger notch and drops coverage to about 30 ft² per bag, so trowel size matters more than tile size in the calculation.

Question 4

What size notched trowel should I use?

Accepted Answer

Match the notch to the tile: 1/4-inch square notch for tile up to 8 inches, 1/4 × 3/8 for 8–16 inches, and 1/2-inch for large-format. The goal is 80% mortar coverage on the tile back for a dry area and 95% in a wet one.

Question 5

How wide should tile grout lines be?

Accepted Answer

One-sixteenth to 1/8 inch for rectified tile, 3/16 for standard ceramic, and 1/4 or wider for handmade or slate. Anything under 1/8 inch needs unsanded grout; sanded grout will not compact into a joint that narrow.

Question 6

How long before I can walk on new tile?

Accepted Answer

Twenty-four hours before light foot traffic and 48 to 72 hours before grouting, though fast-setting mortars cut that. Walking on tile before the mortar cures breaks the bond, and the tile will sound hollow long after it looks fine.

Question 7

Do I need backer board under tile?

Accepted Answer

On a floor, yes, unless the subfloor is concrete — cement board or an uncoupling membrane over plywood. Deflection is what cracks tile and grout, and drywall or bare plywood moves far more than tile can tolerate.

Question 8

Should I start tiling from the centre or a wall?

Accepted Answer

Lay out from the centre lines, then adjust so you do not end with a sliver at any visible edge. Snap your lines first and dry-lay a row in both directions — a layout that leaves a half tile at the door is far better than a quarter-inch strip at the tub.

Tile Calculator

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