# Bostik J115 Flexible Smooth Finish Grout

Tile grout · Bostik

Bostik J115 Flexible Smooth Finish Grout takes about 5 m² a kilogram, by Bostik Ltd's own figure: “Approx. 5m² per 1kg mixed grout at 2mm joint width”. Bostik Ltd's other figures are in the table below.
Source: Bostik Ltd, Bostik J115 Flexible Smooth Finish Grout technical data sheet, read 12 October 2026.

What it is for, in the maker's words: “Bostik J115 FLEXIBLE SMOOTH FINISH GROUT is a professional quality, cementitious, polymer-modified grout suitable for use on both walls and floors” (Bostik J115 Flexible Smooth Finish Grout technical data sheet, read 12 October 2026).

## The maker's figures

| Figure | The maker's words |
|---|---|
| about 5 m² a kilogram | “Approx. 5m² per 1kg mixed grout at 2mm joint width” |
| about 0.6 m² a kilogram | “Approx. 0.6m² per 1kg mixed grout at 15mm joint width” |
| 0.23 kg a square metre | “2mm 300 x 300 x 9mm 0.23kg/m2” |
| 0.57 kg a square metre | “5mm 200 x 200 x 6mm 0.57kg/m2” |
| 1 kg a square metre | “8mm 300 x 300 x 10mm 1.0kg/m2” |
| 1.62 kg a square metre | “15mm 300 x 300 x 9mm 1.62kg/m2” |
| 2.16 kg a square metre | “10mm 200 x 100 x 8mm 2.16kg/m2” |
- The conditions the maker names: Each figure is for the notch, bed, tile or joint the maker names beside it. An uneven surface, a larger notch or buttering the backs of the tiles takes more.
- Waste: None of these figures adds anything for what is left in the bucket or spilt.

## What one bag covers at the maker's rate

| Rate | A 5 kg bag |
|---|---|
| about 5 m²/kg (“Approx. 5m² per 1kg mixed grout at 2mm joint width”) | about 25 m² |
| about 0.6 m²/kg (“Approx. 0.6m² per 1kg mixed grout at 15mm joint width”) | about 3 m² |
| 0.23 kg/m² (“2mm 300 x 300 x 9mm 0.23kg/m2”) | 21.7 m² |
| 0.57 kg/m² (“5mm 200 x 200 x 6mm 0.57kg/m2”) | 8.8 m² |
| 1 kg/m² (“8mm 300 x 300 x 10mm 1.0kg/m2”) | 5 m² |
| 1.62 kg/m² (“15mm 300 x 300 x 9mm 1.62kg/m2”) | 3.1 m² |
| 2.16 kg/m² (“10mm 200 x 100 x 8mm 2.16kg/m2”) | 2.3 m² |

Arithmetic on the maker's figure: the bag's kilograms divided by a rate a square metre, or times an area a kilogram, with nothing added for waste.

## Sizes

5 kg bag

## Where to buy it

The page has the shops' own searches for it, and any link there that is paid for is marked Ad: https://buildbatch.co.uk/products/bostik-j115-flexible-smooth-finish-grout/#where-to-buy. BuildBatch sells nothing and compares no prices.

## Questions

**How much does a 5 kg bag of Bostik J115 Flexible Smooth Finish Grout cover?** Bostik Ltd gives a rate a square metre, not an area a bag. At its rates a 5 kg bag covers about 25 m² (“Approx. 5m² per 1kg mixed grout at 2mm joint width”), about 3 m² (“Approx. 0.6m² per 1kg mixed grout at 15mm joint width”), 21.7 m² (“2mm 300 x 300 x 9mm 0.23kg/m2”), 8.8 m² (“5mm 200 x 200 x 6mm 0.57kg/m2”), 5 m² (“8mm 300 x 300 x 10mm 1.0kg/m2”), 3.1 m² (“15mm 300 x 300 x 9mm 1.62kg/m2”) and 2.3 m² (“10mm 200 x 100 x 8mm 2.16kg/m2”): the bag's kilograms divided by the rate, with nothing added for waste.

**How much Bostik J115 Flexible Smooth Finish Grout per square metre?** Bostik Ltd states 0.23 kg a square metre (“2mm 300 x 300 x 9mm 0.23kg/m2”), 0.57 kg a square metre (“5mm 200 x 200 x 6mm 0.57kg/m2”), 1 kg a square metre (“8mm 300 x 300 x 10mm 1.0kg/m2”), 1.62 kg a square metre (“15mm 300 x 300 x 9mm 1.62kg/m2”) and 2.16 kg a square metre (“10mm 200 x 100 x 8mm 2.16kg/m2”).

**What is Bostik J115 Flexible Smooth Finish Grout for?** Bostik Ltd says: “Bostik J115 FLEXIBLE SMOOTH FINISH GROUT is a professional quality, cementitious, polymer-modified grout suitable for use on both walls and floors” (Bostik J115 Flexible Smooth Finish Grout technical data sheet, read 12 October 2026).

**What sizes does Bostik J115 Flexible Smooth Finish Grout come in?** The catalogue lists 5 kg bag. A shop may not stock every size.

## Where the figures come from

- Bostik Ltd, Bostik J115 Flexible Smooth Finish Grout technical data sheet (https://www.bostik.com/files/live/sites/shared_bostik/files/documents-brochures/United%20Kingdom/TDS/bostik-uk-tds-j115-flexible-smooth-finish-grout): coverage and what it is for, read 12 October 2026.

Written with AI tools; not yet checked by a tradesperson. Follow the bag's own instructions.

The page: https://buildbatch.co.uk/products/bostik-j115-flexible-smooth-finish-grout/