For small and medium ceramic wall tiles on a sound indoor wall, a cementitious adhesive classed C1 under EN 12004, with reduced slip (T), is usually suitable. Larger formats, heavier tiles, exterior walls and difficult backgrounds need an improved C2 adhesive, often with deformability (S1).
The final choice belongs to the installer and the adhesive maker's data sheet, based on the tile, the background and the conditions. As an importer, you can make it easier by giving the right information with your tiles.
How EN 12004 classes work
EN 12004 classifies tile adhesives by type and by performance. The international equivalent is ISO 13007-1. The code on the bag tells you what the adhesive has been tested to do.
- C is a cementitious adhesive, D a dispersion (ready-mixed) adhesive, and R a reaction resin adhesive.
- Class 1 is a normal adhesive; for cementitious types, C1 means a tensile adhesion of at least 0.5 N/mm² in the standard tests.
- Class 2 is an improved adhesive; C2 means a tensile adhesion of at least 1 N/mm².
- T means reduced slip: a tile placed on the wall slides no more than 0.5 mm, which matters on walls.
- E means extended open time, so the adhesive stays workable for longer once spread.
- F means fast setting, for work that must be grouted or used quickly.
- S1 means deformable and S2 highly deformable, for surfaces that move with heat or settlement.
Matching the adhesive to the job
- Small porous wall tiles on a sound indoor plaster or render wall: C1T is commonly enough.
- Larger wall formats, such as 300x600 mm and above: an improved C2T adhesive, often with E for open time.
- Porcelain tiles on walls: C2, since the dense body absorbs almost no water and needs stronger adhesion.
- Exterior walls and elevation tiles: C2 with S1 is the usual starting point, with full adhesive cover.
- Plasterboard, timber or other light backgrounds: follow the board maker's rules, which may call for a deformable or dispersion adhesive.
- Showers and wet rooms: a suitable adhesive over a waterproofing layer, to the waterproofing maker's system.
The body of the tile changes the choice. Ceramic and porcelain wall tiles behave differently, as explained in ceramic versus porcelain wall tiles. Exterior use has extra rules, covered in elevation tiles and outdoor use.
Fixing practice matters too
Even the right adhesive fails if it is applied badly. Installers should use the notched trowel size the maker recommends, press tiles firmly, and check that the back is well covered. Large and exterior tiles often need adhesive on both the wall and the tile back.
Movement joints are needed at corners, around the edges of a wall and at intervals on large areas. Missing joints are a common cause of tiles cracking or coming loose.
What you can give your customers
- The body group, size, thickness and weight per square metre of each tile.
- A note on whether the tile is for interior walls only or also for exterior walls.
- A general recommendation of the adhesive class, telling installers to follow the adhesive maker's data sheet.
- A reminder to leave movement joints and to check the background is sound and dry.
Next step
We collect the tile data your installers need and check it against the test reports. To prepare a product information pack for your range, book a free sourcing review.