Give your customers the factory's own installation guide, plus a short sheet covering substrate, adhesive, coverage, handling, joints and cutting. Large slabs fail on site far more often from poor installation than from faults in the slab.
Your guidance protects you as well as the customer. When a complaint arrives, the first question is whether the slab was installed as instructed. If you never gave instructions, that question is hard to answer.
Substrate
- The floor or wall must be very flat, because a large slab cannot follow dips without hollow spots and lippage.
- The substrate must be clean, dry, stable and fully cured, with any cracks repaired.
- Heated floors, timber floors and old tiles need specific preparation, and the factory or adhesive maker should approve the method.
- Existing movement joints in the building must carry through the slab finish.
Adhesive and coverage
Adhesives for tiles are classified under EN 12004. For large porcelain slabs, installers commonly use an improved cementitious adhesive, class C2, with deformability class S1 or S2. S1 is deformable and S2 highly deformable, which helps the bond cope with small movements in a large panel.
Coverage matters as much as the adhesive. Slabs need full contact, with adhesive on the substrate and back-buttered on the slab. Hollow spots under a slab are a main cause of cracks under load. Ask the adhesive maker for its large-format method, and follow the slab factory's guide where they differ.
In the US, ANSI A108.19 covers interior installation of gauged porcelain tiles and panels or slabs. Point US customers to it.
Handling on site
The warehouse side of handling is covered in unloading and handling slabs.
- Carry slabs on edge, never flat by the ends.
- Use slab frames or rails with suction cups for large sizes, and at least two trained people.
- Check every slab for damage, shade and batch before it is laid, because a laid slab is hard to replace.
- Lay each book-matched slab in its numbered position and the right way up.
Joints and levelling
- Use the minimum joint width the factory recommends; very tight joints leave no room for small size differences.
- Use a levelling clip system to reduce lippage while the adhesive sets.
- Include perimeter and field movement joints as the installation standard and the factory guide require.
- Do not lay long slabs in a half offset pattern unless the factory approves it, because any bow shows at the joints.
Cutting and dust
Slabs must be cut with porcelain-rated diamond tools while fully supported. Cut-outs need rounded inside corners. Cutting releases crystalline silica dust, so wet cutting or dust extraction and suitable respiratory protection are expected under most workplace safety rules. Our guide on cutting, drilling and edging slabs on site covers this in more detail.
Care after installation
- Clean off adhesive and grout residue before it hardens, using products the factory approves.
- List cleaning products to avoid, such as strong acids or abrasive powders on polished surfaces.
- Advise the use of trivets on worktops, as explained in slab heat and scratch resistance.
Next step
We collect installation, fabrication and care documents from the factory in English with every order, so you can pass them on. To build a slab range with full support documents, book a free sourcing review.