t is possible to update a wall or floor tiling scheme by laying new tiles on top of old. A new and additional layer of tiling may cause problems with existing fittings and furniture. It must be remembered that, for floors in particular, the new tiling installation will raise the floor level and doors and furniture may have to be cut in order to fit.
Existing wall tiles
Preparation technique
The most important preparatory step is to ensure that the existing tile surface is clean and dry and that all surface dirt and grease is removed.
Remove any loose tiles and fill the gaps with PCI’s Polycret fast track repair mortar.
Remember that the tiling weight will increase when installing this new layer of tiles, and this is especially important for walls where this weight may exceed the limit recommended for plasterboard or plaster backgrounds.The recommended maximum weight is 32 kg per m2 for plasterboard and 20 kg per m2 for plaster.
If the existing tiles have a glazed ceramic surface, the use of a primer, such as PCI’s Primer 303, will greatly improve the bond between the old and the new tiles.
Adhesive application
Grouting
Once the adhesive bed has set, grouting can be undertaken.
Choose the grout to suit the situation, and for wide joints (over 3mm) use a grout suitable for wide joints.
Drying will vary according to the site conditions.
Movement Joints
Please refer to Special Situations Bulletin 1 due to the complexity of this subject.
Existing ceramic and quarry tiles/natural stone and terrazzo bases
Preparation technique
The most important preparatory step is to ensure that the existing tile surface is clean and dry and that all surface dirt and grease is removed using suitable cleaning products depending in the previous usage of the floor. Some quarry tiles may have too much ingrained dirt and grease and the surface may have to be removed with and industrial cleaner (in a circular motion).
Remove any loose tiles and fill the gap with a fast track repair product, such as PCI’s Polycret 20 or Novoment M1 or Z1.
Prime the floor with a neat application of a product such as PCI’s Primer 303, or use a reinforced decoupling matting system such as those from Shlüter, following the manufacturer’s requirements.
Adhesive application
Use a flexible adhesive for tile-on-tile floor work, such as PCI’s Tilefast 6 Rapidflex.
Grouting
Once the adhesive bed has set, grouting can be undertaken.
Choose a grout to suit the situation, and for wide joints (over 3mm) use a grout suitable for wide joints.
Drying will vary according to the site and ambient conditions.
For vitrified or porcelain tiles, use PCI’s Groutfast 20 Rapidflex to promote bond strength at the tile/grout interface.
Movement Joints
Please refer to Special Situations Bulletin 1 due to the complexity of this subject.
For more information, contact PCI’s Techincal Services Department on 0161 794 7411