Tiling to bitumen surfaces
All surfaces should be dry, clean and strong enough to support the additional weight of tiling without deflection. All traces of dirt, dust, laitance and other contamination must be removed. Substrates should be true and sufficiently flat to allow Norcros Pro Board to be fixed without leaving any voids beneath the boards. Porous or dusty surfaces must be sealed using Norcros Prime Bond diluted 1: 4 with water.
(Refer to the Norcros Pro Board product data sheets for information on the range of boards available. It should be noted that Norcros Wedgeboard is also available as part of this system. Wedgeboard is manufactured with a pre-determined fall of minimum 1% [20mm thick reducing to 8mm] and is ideal for use in areas such as balconies and wet rooms which require floors to be laid to falls.)
Stir the contents of Ultim8 B+ bucket. Use a notched mosaic trowel to apply the adhesive to the bitumen surface. Lay Norcros Pro Board of a suitable thickness (6mm for solid substrates and 10mm for timber substrates) into the adhesive bed and press firmly to collapse the ribs. Allow the adhesive to dry. In areas which may be subject to wetting, tape joints between the boards using Norcros Butyl Waterproofing Tape. Once the adhesive has dried, tiles may be fixed using any of the Norcros Flexible cement-based adhesives.
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, 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 larger internal floor areas, intermediate movement joints should be provided to form bays of size not greater than 10m x 10m
d. In larger external floor areas, intermediate movement joints should be provided to form bays of size less than 10m x 10m
e. On suspended floors, stress relieving joints should be inserted where flexing is likely to occur, e.g. over supporting walls or beams.
f. Internal floors, which might be subjected to significant thermal changes, i.e. direct sunlight in atria, or underfloor heating etc, the floor area should be divided up by intermediate movement joints provided at 5m intervals in both horizontal directions to provide 25m2 bays. N.B. These bay sizes may be increased to 40m2 when Norcros Permalayer anti-fracture matting is used.
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.
Tiles may be fixed in a solid bed of either Norcros Rapid Porcelain Grey or White, Norcros Thick Bed Stone & Porcelain or Norcros S1 adhesives. 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 any risk of staining, the tiles should be fully sealed using a proprietary sealer before grouting begins.