Materials and Tools · 4 lessons

Which tile adhesive class?

2 min read · self-test time extra

The code on a bag of tile adhesive is a short description of how it behaves. Once you can read it, choosing one gets much easier.

Our wall and floor tiling path is in public beta: some lessons are still being checked.

The first letter: what it's made of

Adhesive classes come from BS EN 12004. C means cementitious (a powder you mix with water), D means dispersion (ready-mixed paste) and R means reaction resin, such as epoxy.

The number: how well it grips

Class 1 is a normal adhesive and class 2 is improved, with higher bond strength. Porcelain soaks up very little water, so makers usually call for a class 2 adhesive to hold it.

The extra letters

F sets fast, T stops tiles sliding down a wall, and E gives you extended open time before the adhesive skins over. S1 is deformable and S2 highly deformable: they flex a little, which helps over heated floors and on backgrounds that move.

Grout has classes too

Under BS EN 13888, CG is cementitious grout, in a normal (CG1) or improved (CG2) class, and RG is reaction resin grout. Epoxy grout costs more and is harder to use, but it resists stains and chemicals in kitchens and commercial floors.

Common mistakes

Using a basic class 1 adhesive for porcelain because it's cheaper.
Ignoring the open time and laying tiles into adhesive that has already skinned over.
Picking a rigid adhesive for a heated or flexing floor where the maker asks for S1.

The lessons this guide comes from

Tile types
Adhesive classes
Choosing an adhesive
Grouts