Tiling to existing wall tiles & impervious surfaces
Check that all surfaces are clean, dry and free from any contamination.
The existing tiles should be degreased and any sealers applied to the tile surface removed as these will act as a release agent and prevent good adhesion. Any loose tiles or voids in the surface should be repaired and made good.
It is essential that the underlying substrate is able to support the additional weight of tiling. Weight limits for substrates are as follows:
Gypsum Plaster = 20kg/m2
Plasterboard = 32kg/m2
Plywood = 30kg/m2
Backer board = 50—85kg/m2 (check with board manufacturer)
Tiling should be set out from the centre of the walls, either the centre of a tile in the centre of the wall or the joint between two tiles in the centre of the wall, whichever option will avoid small cuts of the tiles.
Make a gauge rod using a length of straight timber. Along the length of the timber mark out the width of the tiles, leaving a gap at least 2mm wide between each tile. Set out the horizontal position of the tiles so that the same size cuts are made either side of windows etc, avoiding any small cuts.
At the lowest point of the wall to which you are tiling, such as the skirting board, work surface etc, place an uncut tile and draw a line along the top of the tile. Nail a batten below this line, using a spirit level to make sure it is level. The first line of tiles will rest on this batten.
Measure the width of the wall and mark the centre point. Draw a vertical line down at this centre point using a spirit level to make sure that the line is straight. Start tiling at this centre point.
Porous body wall tiles, not greater than 200mm x 200mm may be fixed with Norcros Ultim8 in dry areas or Ultim8+ in areas which may be subject to wetting. It should be noted that the adhesive will take a minimum of 72 hours to dry before grouting can take place.
To provide a key onto which the adhesive can bond, a slurry bonding coat consisting of 2 parts of cement-based adhesive to 1 part Norcros Prime Bondshould be applied to the surface of the existing tiles using a suitable brush, making sure that the slurry bonding coat covers the whole area. Allow to dry (approximately 1 hour depending upon temperature and humidity. Tiles may be fixed with Norcros One Part Flexible or Norcros Standard Set Flexible S1 adhesive. Grouting may take place approximately 24 hours after fixing.
Using a suitable notched wall trowel held at a 45o angle, spread the adhesive onto the wall to form parallel ribs into which the tiles should be pushed with a firm twisting action, this will collapse the ribs of adhesive and produce a 2-3mm bed of adhesive beneath the tiles. Work in small areas and dis-card any adhesive that begins to dry or ‘skin over’. Tiles with deeply keyed back profiles may need to back buttered. In areas subject to wetting such as showers, it is essential that a solid bed of adhesive is achieved beneath the tiles. Wipe off any adhesive residues from the surface of the tiles using a damp sponge before the adhesive sets. Remove deposits of adhesive which may build up in the gaps between the tiles.
Some porcelain tiles can be difficult to cut and good quality tools are required. These can bought or in some instances hired. A slide cutter and nippers are essential, however an electric wet cutter will make the job easier. For intricate cuts a cardboard template will help to achieve more accurate results.
Allow the adhesive to dry.
Use Norcros Wall Tile Grout. In areas subject to wetting or where movement/vibration is anticipated Norcros Stop Mould Grout, Norcros 4 into 1 Grout or Norcros Super Epoxy may be used.
Clean out any dust, dirt and adhesive from between the tiles and make sure that the joints are dry.
Approximately 3 parts grout powder should be added to 1 part water, ensuring that the powder is added to the liquid to prevent the product from flash setting. Manually mix the grout to reduce the amount of air incorporated into the mix.
Holding a soft rubber grout float at 45o, sweep the mixed grout diagonally across the tiles, ensuring that the grout is pushed fully into the joints. Clean off as much grout from the surface of the tiles as possible and allow the grout to become touch dry. Clean off the grout residues with a damp sponge wiped diagonally across the tiles. Allow the tiles to dry and buff the surface with a dry cloth. Any stubborn residues may be cleaned off with washing up detergent mixed with warm water within 24 hours of grouting.
N.B. Before grouting commences trial a small inconspicuous area to check that the grout does not stain the tiles. If there is any risk of staining, the tiles should be fully sealed using a proprietary sealer before grouting begins.