Tiling prep advice - rendered wall

[Moonhead]

Currently ripping the old tiles out of our bathroom and they are attached to this surface. It looks like render or a bonding coat. Can I stick my new tiles straight onto this or does it need prep like tile backing board? It's a very small space so ideally I want to minimise any increase in the thickness of the walls if possible, so battens are out in terms of options.

 

[Swwils]

Tiling onto a wall substrate requires some careful considerations to ensure the tiles adhere properly and stay in place over time. There are several important factors outlined in standards such as ISO 13007 and BS EN 12004 that should be followed for proper installation. Here are some key points:

1. Structural Soundness: The wall must be structurally sound and capable of supporting the weight of the tiles, adhesive, and grout without any movement. This is especially important in older buildings where the structure may have deteriorated.
2. Flat and Level: The surface should be flat and level. Any variations or defects in the wall can cause problems with the tile installation, including unevenness or potential breakage.
3. Cleanliness: The surface should be clean, free of dust, grease, paint, or any other material that may affect the bond between the adhesive and the substrate.
4. Dryness: The substrate should be dry. This is especially important in wet areas like bathrooms and kitchens. If the substrate is too damp, it could compromise the adhesion of the tiles or lead to mould issues.
5. Porosity: The porosity of the substrate should be considered as it affects the choice of tile adhesive. Highly porous substrates might require a primer to reduce absorbency and prevent the rapid drying of the adhesive.
6. Suitable Material: The substrate material itself should be suitable for tiling. Common substrates for tiling include plaster, plasterboard, cement board, and concrete. Some surfaces, such as wood or certain types of paint, may not be suitable or require specific preparation or products.
7. Thermal and Moisture Considerations: In areas with high thermal or moisture variation, special considerations should be taken. For example, in a bathroom, the use of a waterproof membrane may be needed.

Always follow the tile and adhesive manufacturers' instructions and recommendations for substrate preparation to ensure a successful and long-lasting tile installation.