Tiling to existing floor 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 using one of the Norcros levelling compounds such as Pro 10+, Pro 30 Eco or Pro 50.
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 Bond should 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).
The general rule is to work from the centre outwards. Measure the width and length of the floor and draw a cross in the centre. From the central cross lay out the dry tiles allowing a 3mm wide gap between the tiles to allow for movement stresses within the floor during service. These gaps will be filled with grout once the tiles have been fixed and the adhesive dried. Make sure there are no awkward cuts, some adjustment may be necessary. Always be aware of how the floor will look when you enter the room.
To counteract movement stresses, which can result in tiles cracking and/or debonding. A movement joint should be provided around the perimeter of the room. A gap no less than 6mm wide and 6mm deep or the depth of the tile should be left at the junction between the walls and the floor. This should be filled with silicone sealant at the end of the job, or if being covered with skirting boards or kitchen units etc. may be left open. In large floor areas, intermediate movement joints should be provided at 8 to 10 metre intervals in both directions.
Fix tiles in a polymer modified cement-based adhesive such as Norcros Rapid Porcelain Tile Adhesive Grey, Norcros Rapid Porcelain & Stone Adhesive White, Norcros Rapid Porcelain S1 or Norcros Thick Bed Stone & Porcelain Adhesive.
Gradually add 3.5 parts of adhesive powder to 1 part of clean cold water and stir until a smooth lump free consistency is achieved. Mix only enough material that
can be used within the pot life of the product (around 30 minutes at 20oC).
Using a suitable notched floor trowel held at a 45o angle, spread the adhesive onto the floor 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 3-4mm solid bed of adhesive beneath the tiles. Work in small areas and discard any adhesive that begins to dry or ‘skin over’. Tiles with deeply keyed back profiles may need to back buttered. Every so often lift a tile to check that it is in full contact with the adhesive and that no voids are left in the adhesive bed. 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. DO NOT WALK ON THE TILES FOR AT LEAST 2-3 HOURS, or until the adhesive has set.
Floor tiles, especially natural stone and porcelain 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 either Norcros Floor & Wall Tile Grout, Norcros Flexible Floor & Wall Tile Grout or Norcros 4 into 1 Grout. Clean out any dust, dirt and adhesive from between the tiles and make sure that the joints are dry.
Approximately 4-5 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.