Tile Adhesive and Grout Calculator: Bags and Kilograms

What it calculates

For a tiled floor or wall, the calculator gives:

• the tiled area in square feet and square metres;
• the tile adhesive in kilograms and whole bags;
• the grout in kilograms, and the grout consumption in kg per square metre.

To count the tiles themselves, use the flooring quantity calculator.

Inputs

Tiled area is in square feet, less any openings; the square metre figure is shown under the field.

Tile length and tile width are in millimetres.

Joint width is the spacer or joint width in the tiling specification, in millimetres.

Tile thickness is in millimetres and is used as the depth of the grout joint.

The assumptions panel holds the adhesive consumption, the adhesive bag size, the grout density and the wastage allowance.

Method

1. Area in m² = area in sq ft × 0.092903.
2. Adhesive = area in m² × consumption in kg/m² × (1 + wastage).
3. Adhesive bags = adhesive ÷ bag size, rounded up.
4. Grout in kg/m² = (L + W) / (L × W) × joint width × joint depth × density.
5. Grout = area in m² × grout in kg/m² × (1 + wastage).

In step 4, L, W, the joint width and the joint depth are in millimetres and the density is in kg/dm³ (the same as kg per litre). (L + W) / (L × W) is the length of joint in each unit of tiled area. Multiplied by the joint's width and depth it gives the depth of grout spread over the area in millimetres, and 1 mm over 1 m² is 1 dm³, so multiplying by the density gives kg per square metre.

Assumptions

The adhesive consumption is the input that matters most. It can vary several-fold between a small notch on a flat wall and a large notch on a floor laid with large-format tiles.

Limitations

• One tile size and joint width at a time. Run each tile type separately.
• Joint depth is taken as the tile thickness. Where the joint is shallower, enter the actual depth.
• The adhesive figure is only as good as the data sheet value. A surface out of level, or back-buttering of large tiles, raises consumption above the data-sheet figure.
• Movement joints are not deducted. Perimeter and field movement joints are filled with sealant, not grout, as the tiling specification sets out.
• It does not choose the adhesive or the grout. The adhesive class, and a cement or reaction resin (epoxy) grout, are a specification decision for the tile, background and use.

Worked example

500 sq ft of 600 × 600 mm tiles, 9 mm thick, with 3 mm joints, adhesive at 5 kg/m² in 20 kg bags, grout at 1.6 kg/dm³ and 10% wastage:

The floor needs 13 bags of adhesive and about 7.4 kg of grout. With 300 × 300 mm tiles of the same thickness and joint, the grout doubles to 0.288 kg/m², or about 14.7 kg.

How engineers use it

On a fit-out, tiling is measured from the drawings in square metres for each tile type, and the specification names the adhesive class, the trowel notch, the joint width, the grout type and the movement joints. Adhesive and grout quantities then follow from the manufacturers' data sheets for those products. A calculation like this one is the quick check that a supplier's or tiler's material estimate is in the right range.

When a professional design must replace it

Use the calculator to estimate how much adhesive and grout to buy, or to check an estimate. Replace it with a measured take-off and a written tiling specification for a whole building, for wet areas, external or facade tiling, heavy or large-format tiles, and chemical or hygiene areas. The tiling specification and the products' data sheets, not a rule of thumb, decide what is used.