Start with one number
Maira Tile Bond 3100 covers roughly 4.5 to 6.6 m² per 20 kg bag. That looks like a wide range until you notice what moves it: bed thickness. The lower figure is a 3 mm bed, the upper one is 2 mm.
Both work out to about 13.4 m²·mm per bag — a bag covers 13.4 square metres at one millimetre thick. Divide by your bed thickness and you have your coverage:
- 2 mm bed → about 6.7 m² per bag
- 3 mm bed → about 4.5 m² per bag
- 4 mm bed → about 3.4 m² per bag
- 6 mm bed → about 2.2 m² per bag
That single constant is worth remembering, because it lets you re-estimate on site when the trowel changes.
Bed thickness follows the tile
You do not choose bed thickness freely — the tile and the trowel choose it for you. A useful rule: the finished bed is roughly half the depth of the trowel notch, because the ridges collapse when the tile is pressed in. A 6 mm notch gives about a 3 mm bed.
Small mosaics sit in a thin bed. Standard floor and wall tiles sit around 3 mm. Large format needs more, because a bigger tile spans more of the substrate's imperfections. There is a full trowel guide here.
Flatness is the hidden cost
Coverage figures assume a flat substrate. They are measured on one, and your floor probably is not. Every dip you fill with adhesive is material that never appears in the calculation.
On a wavy screed the same tiles can take half as much again as the figures suggest. If the substrate is visibly out of level it is nearly always cheaper to level it first than to fill it with adhesive.
A worked example
Say you are tiling 80 m² of floor with standard 300 × 300 tiles at a 3 mm bed.
- Coverage at 3 mm: 13.4 ÷ 3 = 4.5 m² per bag
- Bags before wastage: 80 ÷ 4.5 = 17.8
- Add 5% for wastage: 17.8 × 1.05 = 18.7
- Round up: 19 bags, which is 380 kg
The coverage calculator on the main page does exactly this arithmetic, including the wastage allowance.
Two mistakes worth avoiding
Ordering exactly what the sum says. Five per cent covers normal waste — what sticks in the bucket, what goes off before you reach it, the odd damp bag. It does not cover an uneven substrate or a change of trowel. On an unfamiliar floor, allow ten.
Ordering in two trips. Cement-based products vary slightly between production batches, and the colour of the set adhesive can differ enough to notice in a light grout joint. Order the whole job at once.
Storage between now and then
Tile Bond 3100 keeps for at least six months in its unopened bag, stored dry between +5 °C and +35 °C. Keep bags off the floor and out of the rain: cement powder that has taken up moisture will not perform, whatever the date says.
Note: the figures here are typical values for Maira Tile Bond 3100 and are given as guidance. Real results vary with substrate, tile format, trowel size, temperature and site conditions. Confirm quantities and working times with Ali Traders before you order or start work.