Tile standards

Tile standards explained: what the codes on the box mean

The code of practice: BS 5385

BS 5385 is the British Standard code of practice for wall and floor tiling. It comes in parts: part 1 covers internal wall tiling, part 3 covers floor tiling and part 4 covers tiling in wet and specific conditions, such as showers. Tilers, adhesive makers and board makers all refer to it, so it's the yardstick for how a job should be done.

The Tile Association's answers to common questions quote several of its rules. For example, wall joints should be at least 2mm wide for tiles under 0.1m² with no side over 600mm, and at least 3mm for tiles from 0.1m² to 1m² with no side over 1200mm. Floor joints should be at least 3mm wide.

Porcelain and ceramic: BS EN 14411

Ceramic tiles are classified under BS EN 14411, largely by how much water they absorb. Tiles with water absorption of 0.5% or less fall into group BIa, and that is the group usually sold as porcelain. Other ceramic tiles absorb more water, and some absorb a great deal more.

Low absorption is why porcelain is dense and hard-wearing. It also means porcelain needs an adhesive that bonds to a non-porous tile, so check the adhesive bag says it is suitable for porcelain.

Adhesive classes: BS EN 12004

Every tile adhesive bag carries a short code under BS EN 12004. The first letter is the type: C for cement-based, D for ready-mixed (dispersion) and R for reaction resin. The number is the class: 1 is normal and 2 is improved.

Letters after that add a property. F means fast setting, T means reduced slip (useful on walls, so tiles don't slide down) and E means extended open time. S1 means the adhesive is deformable and S2 means it is highly deformable, which matters where there is movement, such as over underfloor heating. So C2TE S1 is an improved cement-based adhesive with reduced slip, extended open time and some flexibility.

Grout classes: BS EN 13888

Grouts are classified under BS EN 13888. CG1 is a normal cement-based grout and CG2 is an improved one. A W after CG2 means reduced water absorption and an A means high abrasion resistance. RG is a reaction resin grout, usually epoxy.

The Tile Association notes that narrow joint grouts are typically used for joints of 1 to 3mm, and wide joint grouts for joints over 3mm. It also says joints should be at least 6mm deep, or the full depth of the tile if it is thinner, and free of dust before you grout.

Slip resistance

The Health and Safety Executive measures floor slipperiness with the pendulum test, which gives a pendulum test value (PTV). In its guidance on assessing slip resistance, a PTV of 36 or more means low slip potential, 25 to 35 means moderate and 24 or below means high.

Many tiles are sold with an R rating instead, from R9 to R13, based on a German ramp test with oil and safety boots. HSE has reservations about that test and warns that R9, and in some cases R10, surfaces will be slippery when wet. If a floor will get wet, ask for the wet PTV.

How much weight a wall can take

The Tile Association gives these maximum weights for wall tiling, including the tile and the adhesive. A dry, well-adhered gypsum plaster wall can take 20kg per square metre. Plasterboard without a plaster skim can take 32kg per square metre. Tile backer boards vary by type and thickness, so check the board maker's figure.

Thick tiles can go over these limits quickly. The Tile Association says 20kg per square metre is about the same as ceramic tiles up to 8mm thick or natural stone up to 7mm thick, so weigh a tile and work it out per square metre before you buy.

Preparation and curing times

The Tile Association says gypsum plaster should cure for at least 4 weeks before tiling, and a cement and sand screed should cure for at least 7 days and then dry for a further 2 weeks. It advises using a proper primer, and says PVA should never be used as one.

It also says BS 5385 part 4 recommends leaving a newly tiled shower for at least 14 days before you use it, and that timber is no longer considered a suitable background for wall tiles.

A note on this guide

This is general information, not legal or professional advice. Rules change, so please check the official sources we link to before you make a decision.