The asphalt base should be laid in accordance with section four of CP 204: Part 2: 1970 or CP 144: Part 4 and be either flooring or paving grade. It should be noted that roofing grade asphalt/roofing felt is not suitable to receive a tiled finish without overboarding with Norcros Pro Board laid into a bed of Norcros Ultim8 B+ (refer to the How to… sheet for tiling to bItumen surfaces).
The asphalt must be laid onto a rigid base, i.e. concrete/ cement: sand screed, and have adequate cohesive strength. It must be in suitable condition to receive a tiled finish and be thoroughly clean, dry and free from any contamination. Prime with undiluted Norcros Prime Bond and allow to dry before fixing tiles, or levelling where necessary with either Norcros Pro 10, Pro 10+, Pro 30 or Pro 50 in internal areas and Norcros Pro 50 in external areas.
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 minimum 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, in accordance with British Standard BS5385-3:2014, movement joints should be provided:
a. Over existing and/or structural movement joints
b. Perimeter movement joints should be inserted at door thresholds and where the tiling abuts restraining surfaces such as perimeter walls, columns, curbs, steps and plant fixed to the base
c. In large floor areas, intermediate movement joints should be provided at 8-10 metre intervals.
More information on the provision of movement joints is available in the Norcros How to Sheet ‘Movement Joints in Tiled Installations’.
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.
Fix tiles in a polymer modified cement-based adhesive such as Norcros Rapid Porcelain Grey or White, or Norcros Thick Bed Stone & Porcelain or Norcros Rapid Porcelain S1 Adhesive. Refer to the packaging or product data sheets for information regarding mixing ratios. 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). N.B. This will be extended in cold weather and reduced in warm conditions.
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.
Allow the adhesive to dry.
Use either Norcros Flexible Wide Joint 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 a risk of any staining, the tiles should be fully sealed using a proprietary sealer before grouting begins.