How To Category: Floors

Tiling to timber floors with undertile heating

PREPARATION
It is essential that the existing timber floor is level before proceeding and able to support the additional weight without excessive deflection. To increase the efficiency of the undertile heating, overlay the floor with Norcros Pro Board and fix either in a bed of Norcros Rapid Porcelain Adhesive or with suitable screw fixings (refer to Pro Board product data sheet).
** Green chipboard where a wax coating is present is not suitable as a tiling substrate.
The undertile heating cables/mat should be laid onto the boards in accordance with manufacturer recommendations. Encapsulate the heating cables in a layer of either Norcros PRO 10+. PRO 30 Fast Track Eco or PRO 50 Levelling Compound. This will protect the cables from damage. Allow to dry.

SETTING OUT
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.
Pro 10+ Levelling CompoundPro 30 Levelling CompoundPro 50 Levelling Compound

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. 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 25m2bays. N.B. These bay sizes may be increased to 40m2 when Norcros Permalayer anti-fracture matting is used.
Rapid Porcelain Tile AdhesiveRapid Porcelain and Stone AdhesiveRapid Porcelain and Stone S1 Tile AdhesiveRapid Porcelain S1 Tile AdhesiveThick Bed Porcelain and Stone AdhesiveThick Bed Porcelain and Stone Adhesive

FIXING
Fix tiles in a highly polymer modified adhesive such as Norcros Rapid Porcelain Tile Adhesive Grey, Norcros Rapid Porcelain & Stone Adhesive White, Norcros Rapid Porcelain S1 Adhesive or Norcros Thick Bed Stone & Porcelain Grey/White or Rapid Porcelain S1 adhesive for large format tiles.

APPLICATION
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.

CUTTING TILES
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.

GROUTING
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.

Flexible Wide Joint Tile Grout4 Into 1 Wall and Floor Tile Grout

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.

N.B. The heating must not be switched on for at least 14 days after completion of tiling, raising the temperature gradually at a rate of 5oC per day.

Tiling pool tanks

CONSTRUCTION & TESTING

  • Pool tanks are generally constructed as follows:
  • Reinforced concrete blocks or reinforced patent blockwork + cement: sand render
  • Reinforced concrete within a cavity wall construction
  • Cast reinforced concrete
  • Gunite/ shotcrete (pneumatically applied concrete)

The watertightness of the pools shell must be tested before the application of the render, screed and tile finishes, as per British Standard BS 8007: 1987 Section 9.2 which states:
“The structure should be cleaned and initially filled to the normal maximum level with the specified liquid (usually water) at a uniform rate of not greater than 2m in 24 hours.
When first filled, the liquid level should be maintained by the addition of further liquid for a stabilising period while absorption and autogenous healing take place. The stabilising period may be 7 days for a maximum design crack width of 0.1mm or 21 days for 0.2mm or greater. After the stabilising period the level of the liquid surface should be recorded at 24h intervals for a test period of 7 days. During this 7 day test period the total permissible drop in level, after allowing for evaporation and rainfall, should not exceed 1/500th of the average water depth of the full tank, 10mm or another specified amount.
Should the structure not satisfy the 7-day test, then after the completion of the remedial work it should be refilled and if necessary left for a further stabilising period; a further test of 7 days duration should then be undertaken in accordance with this clause.”

It should be noted that when using reinforced concrete blocks and/or patented blockwork, the rendering forms part of the watertight construction and should be included in the above test.

Pool tanks that are out of the ground need particular attention in the design stages particularly if they are constructed/installed on upper floor levels.

DRYING TIMES
The minimum time intervals between stages of the work are:

  • Completion (curing) of pool shell to start of rendering/screeding/tiling—6 weeks
  • Completion of rendering/screeding to start of tiling—3 weeks
  • Completion of tiling to start of grouting—3 days
  • Completion of grouting and sealing of movement joints to filling of pool—3 weeks

Longer periods may be required in wet weather.

Filling, emptying and heating pool: Minimise stresses.

  • Maximum filling and emptying rate—750mm/24 hours
  • Maximum rate of heating water—0.25oC/hour

TILE SELECTION
Must have a low water absorption of 3% or preferably less. Suitable tile classifications are:

  • Extruded type AIa or AIb—BS EN 14411
  • Dry pressed type: Bia or B1B—BS EN 14411

Product suitability should be obtained by the tile manufacturer.

PREPARATION
Loose or hollow portions must be cut out and repaired. All dusty or porous substrates should be thoroughly dry brushed prior to priming with Norcros Prime Bond diluted 1: 4 with water. Allow to dry.

FIXING
Fix the tiles using Norcros One Part Flexible Adhesive or Norcros Standard Set Flexible S1 Adhesive.
Gradually add 20kg of One Part Flexible powder to 5.5– 5.7 litres of water and mix to a thick, creamy, slump-free consistency. Mix only enough material that can be used within the pot life of the product (around 4 hours).
Apply the adhesive using a suitable notched trowel held at a 45o angle to form parallel ribs into which the tiles should be pushed with a firm twisting action to produce a 3-6mm thick solid, void-free bed 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 be 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 resi-dues 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 TRAFFIC THE TILES FOR AT LEAST 18-24 HOURS or until the adhesive has set.
Allow the adhesive to dry for a minimum of 3 days before grouting commences.

GROUTING
Allow the adhesive to dry.
In hard water areas (>200mg/l (CaCO3) a cement-based grout such as Norcros Stop Mould Flexible (BS EN 13888 CG2) may be used.
In soft water areas (<200mg/l (CaCO3), hydrotherapy pools, salt water pools or where wave machines etc. are to be used, it is essential that an epoxy resin grout such as Norcros Super Epoxy (BS EN 13888 RG1) is used.
Clean out any dirt, dust or adhesive from between the tiles and ensure that the joints are dry before grouting commences.

MOVEMENT JOINTS
In accordance with British Standard BS 5385: Part 4 movement joints should be incorporated as follows:

  • In the pool lining around the perimeter at the junction of the bottom and sides
  • At vertical corners and at any change of plane in the bottom.
  • If joints between tiles are less than 6mm it is advisable to insert additional movement joints down the pool sides and across the bottom in a continuous loop at 6m intervals or less to suit design considerations.
  • Movement joints should coincide with the structural junction of the pool shell and the surround slab and where tiling abuts walls, drainage channels and other features.
  • Intermediate movement joints should be inserted at intervals of 6m or less.
  • Allow 3 weeks following grouting and sealing before filling the pool.

COVERAGES
Norcros One Part Flexible—Approximately 4-5kg/m2 based upon a 3-4mm solid bed
Norcros Standard Set Flexible S1— Approximately 3-4kg/m2 based upon a 3-4mm solid bed.
Norcros Stop Mould Flexible Grout—Approximately 0.6kg/m2 based upon a 250mm x 125mm x 8mm tile with a 3mm wide joint or 1.1kg based upon a 25mm x 25mm x 4mm mosaic with a 2mm wide joint.
Norcros Super Epoxy– 0.5kg/m2 based upon a 250mm x 125mm x 8mm tile with a 3mm wide joint or 1kg/m2 based upon a 25mm x 25mm x 4mm mosaic with a 2mm wide joint.
The following formula may be used to calculate the approximate grout coverage:

(Tile Length (mm) + Tile Width (mm) x Tile Thickness (mm) x Joint Width (mm) x S.G = kg/m2
(Tile Length x Tile Width)

S.G = 2.0 No Mould Flexible; 1.6 Easy Clean Epoxy
All measurements MUST be in mm. Always allow 10% for wastage

Norcros pro board fixing instructions

Fixing to Wooden Floors
By Adhesive Norcros Pro Boards may be laid using Norcros Rapid Porcelain Grey Adhesive – solvent based or ready mixed adhesives MUST NOT be used. Boards should be thoroughly bedded and laid in a chequer plate fashion making sure that there are no air gaps between the boards.

By Mechanical Fixing Norcros Pro Boards can be installed using mechanical fixings to flat and level timber floors using approximately 12 fixings per 1200mm x 600mm board-fix using Norcros 35mm diameter fixing washers and suitable screws.

WHEN USING MECHANICAL FIXINGS MAKE SURE TO AVOID ELECTRICAL CABLES OR PIPEWORK THAT MAY BE CONCEALED UNDER THE FLOOR. THE CORRECT SCREW LENGTH SHOULD BE USED.

Fixing to Concrete Floors
Prior to fixing the Norcros Pro Boards, all traces of loose material should be removed back to the concrete substrate. The floor should be level and dust free. We recommend sealing the floor with a suitable water resistant primer before the boards are laid. New concrete or screed should be correctly cured prior to fixing the boards. The boards can be fixed using Norcros Rapid Porcelain Grey Adhesive – SOLVENT BASED OR READY MIXED ADHESIVES MUST NOT BE USED. Apply a bed of adhesive to the floor using an 8mm square notched tiling trowel. Norcros Pro Boards should be thoroughly bedded into the adhesive and laid in a chequer plate fashion ensuring that no voids remain beneath them. DO NOT ALLOW THE ADHESIVE TO FORM A DRY SKIN PRIOR TO BONDING THE BOARDS. Any slight depressions in the concrete floor will normally be taken up with the thickness of the adhesive.

Expansion/Movement Joints
Norcros Pro Boards must not bridge expansion/movement joints in the subfloor. The integrity of such joints should be maintained through the board and tile bed and should be sealed in the appropriate manner.

Tile choice for Floors
When choosing tiles for your floor it is important to consider point loading. Applying larger tiles improves the board’s resistance to concentrated loads. For areas that may be subject to concentrated loads over 0.15 N/mm² advice should be sought to determine suitability. All tiles must be fixed using a solid bed of adhesive ensuring no voids remain under the tiles. Tiles should be fixed using either Norcros Rapid Porcelain Grey, Norcros Rapid Porcelain & Stone White or Norcros Thick Bed Porcelain & Stone adhesive SOLVENT BASED OR READY MIXED ADHESIVES MUST NOT BE USED. The chart below shows resistance to concentrated loads based on 0.15 N/mm² over a range of standard tile sizes.

Tile size examples

300mm x 200mm

150mm x 150mm

100mm x 100mm

50mm x 50mm

Load resistance over tile surface

900kg

337kg

150kg

37.5kg

Tile Fixing to Floors with Under Floor Heating Cable/Mat
Tiles can be laid directly on top of the under floor heating cable/mats, however care must be taken not to damage the heating cable. We therefore recommend that the heating cables are encapsulated in a bed of either Norcros Pro 50 or Norcros 2 Part Levelling Compound prior to fixing tiles. Tiles may be fixed once the levelling compound has fully cured..

Fixing to Brick/Block Walls
Make sure that the existing wall surface is sound and free of dust and grease. If the wall has a finished plaster surface and is in a good condition, it may be possible to adhere the Norcros Pro Boards without removing the existing plaster, however professional advice on the stability of the wall structure should be sought. Plastered walls MUST be sealed with a neat application of Norcros Prime Bond prior to fixing boards. Norcros Pro Boards should be fixed to walls using Norcros Rapid Porcelain Grey Adhesive. Wherever possible we recommend that the boards are bonded to the wall using a solid bed of adhesive in a similar fashion to fixing tiles. If a Dot and Dab method is preferred, the adhesive dabs must be applied directly to the board. We recommend applying a solid bed of adhesive around the edges of each board with centre dots at a maximum of 300mm centres. To avoid adhesive shrinkage, the adhesive dabs should be no thicker than 30mm. Offer up the board vertically to the wall surface and bed firmly into place. When using a Dot and Dab method we recommend securing the boards using mechanical fasteners (dowels) once the adhesive has set. Mechanical fasteners should be positioned around the perimeter of the boards at a maximum of 600mm centres e.g. for a 2400mm x 600mm board use 5 fasteners down each edge. Tape all joints using either Norcros self-adhesive alkaline resistant tape or Norcros waterproof tape

Fixing to Stud Partition Walls
6mm boards are not suitable for fixing to stud walls. For 10mm and 12.5mm thick boards, vertical studs should be set at *300mm centres. For board thickness of 20mm and above *400mm centres are suitable. All board edges must be supported by timber noggins and fixed using approximately 12 fixings for a 1200mm x 600mm board. Norcros 35mm diameter washers must be used under the head of a steel screw. Screw down until the washer bites into the board. Tape all joints using either Norcros self-adhesive alkaline resistant tape or Norcros waterproof tape (*Stud centres should be set subject to load requirement)

Tile Fixing to Walls
Once the adhesive for securing the boards has hardened and all joints have been taped, tiles can then be fixed directly to the board surface.

Plastering
Prior to skim coating with plaster, the surface of the Norcros Pro Boards should first be sealed using a neat application of Norcros Prime Bond.
Note: Norcros Pro Boards must be stored flat at all times, leaning the boards against a wall can cause them to warp slightly prior to installation. If this occurs they can be straightened by applying a minimal amount of hand pressure. This correction will not affect the performance of the boards. When fixing boards in conditions where the room temperature can fluctuate considerably (e.g. conservatories) it is advisable to control the room temperature allowing the adhesive used to set properly.
All information is given as guidance and if adhered to will perform as intended. We fully guarantee the quality of our boards but as we do not have knowledge of site conditions or the capability of the installer, we cannot accept liability for damage which may arise as a result of installation. Please contact your supplier if you require further information.

Tiling to plywood / plywood overlaid floors

PREPARATION
It is essential that the existing timber floor is stable, clean and in good condition with adequate ventilation beneath the chipboard to prevent atmospheric moisture distortion. The plywood must be WBP/Marine grade screwed down at 300mm centres. All board edges should be fully supported. The board should ideally be a minimum 15-18mm thick. It should be able to support the additional weight without excessive deflection**

Beware of some grades of Eastern European and Far Eastern Plywood which may be susceptible to disinte-gration when wet. Plywood which has been treated/coated may not be suitable to receive a tiled finish as the coating may inhibit adhesion. To the board

To avoid shrinkage defects in new boards, the moisture content of the timber must match that of the finished installation before it is fixed (pre-conditioning). When received on site, the boards should be unpacked and loosely stacked, preferably with spacing stickers between the pieces to allow air to circulate around the timber. Store length ways, placing heavy weights on top of the timber stack to restrict warping of the boards. The length of time that the timber should be pre-conditioned will vary depending upon how closely the timber matches site conditions. If condi-tioning for more than two or three days is required, it is wise to re-stack the timber, moving material from inside the stack to the outside. Conditioning for 14 days or more may be necessary.

In areas which may be subject to wetting, plywood must be tanked using Norcros Wet Seal Tanking Membrane

**To check that movement in the floor is not excessive, fill a tumbler to the rim with water and place it on the floor. Stand approximately 1 metre away from the tumbler and jump on the floor. If the water spills out of the tumbler then the floor should be strengthened with an overlay of either 15-18mm WBP Plywood or 10mm Norcros Pro Board.

SETTING OUT
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 flor 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.

FIXING
Option 1
Fix tiles in a 3-4mm solid bed of Norcros One Part Direct to Wood and allow to dry.
Option 2
Lay Norcros Permalayer anti-fracture membrane onto the plywood in a 2mm bed of Norcros Rapid Porcelain Grey Adhesive & allow to dry before laying tiles in a 3-4mm solid bed of Norcros Rapid Porcelain Grey, Rapid Porcelain & Stone White, Norcros Rapid Porcelain S1 or Thick Bed Stone & Porcelain adhesive. Allow to dry.
Option 3
Overlay the plywood with 10mm thick Norcros Pro Board (refer to product data sheet) before laying tiles in a 3-4mm solid bed of Norcros Rapid Porcelain Grey, Rapid Porcelain & Stone White, Norcros Rapid Porcelain S1 or Thick Bed Stone & Porcelain adhesive. Allow to dry.
Option 4
Overlay the plywood with 15-18mm thick Norcros Pro Board WBP/ Marine grade plywood laid with cross staggered joints and screw fixed to the existing boards at 300mm centres and at 150mm intervals along board edges. Prime back, face and edges with undiluted Norcros Prime Bond and allow to dry before laying tiles in a 3-4mm solid bed of Norcros Rapid Porcelain Grey, Rapid Porcelain & Stone White, Norcros Rapid Porcelain S1 or Thick Bed Stone & Porcelain adhesive. Allow to dry.

APPLICATION
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.

CUTTING TILES
Floor tiles, especially natural stone and porcelain can be difficult to cut and good quality tools are required. These can bought or in some in-stances 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.

GROUTING
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 stain-ing, the tiles should be fully sealed using a proprietary sealer before grouting begins.

Fixing natural stone to concrete / screed floors incorporating underfloor heating systems

PREPARATION
Minimum drying times for new concrete/ sand: cement screeds before installation of heating/ tiles are:
Concrete = minimum 6 weeks
Sand: cement screed = minimum 3 weeks

Once dried the heating should be switched on and the temperature raised at a rate of 5oC per day to operating temperature. The operating temperature should then be maintained for 2-3 days before cooling down to room temperature. The temperature should be maintained at 15oC while installing the flooring. This is to ensure any movement in the screed has taken place prior to the installation of the stone. . On completion of tiling, the heating should be allowed to cool completely and should not be switched on for a minimum of 14 days to allow the adhesive & grout to fully cure. After this time, the heating should be switched on at a rate of 5oC per day to operating temperature. Where it is not possible to operate the heating prior to the installation of the natural stone tiles, cracking of the tiles/slabs is likely to occur.

Generally it is not recommended for stone to be installed on timber floor constructions with piped hot water heating systems using copper or plastic pipes. This is mainly due to the issues regarding the stability of the floor with thermal expansion and contraction occurring in the timber. The pipe work also precludes the installation of additional noggings and stiffening to the joists as required in accordance with British Standard BS 5385 parts 1-5.
N.B. It is essential to ensure that the stone selected is suitable for use on heated floors.

Remove all traces of dust/ dirt/ laitance and prime with Norcros Prime Bond diluted 1: 4 with water. To protect the stone from thermal movement stresses, apply Norcros Permalayer anti-fracture membrane in a 2mm bed of Norcros Rapid Porcelain Grey adhesive and allow to dry.

OPERATING TEMPERATURES
Guidance on the design of underfloor heating is set out in BS EN 1264 Water based surface embedded heating and cooling systems. The maximum surfaces temperatures for natural stone floors laid onto heated concrete/screeds are:

AREA MAXIMUM FLOOR SURFACE TEMPERATURE oC DESIGN ROOM TEMPERATURE
oC
Occupied Area 29 20
Bathroom or similar 33 24

SETTING OUT
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. 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 with a maximum bay length of 8m when Norcros Permalayer anti-fracture matting is used.

CUTTING TILES
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.

FIXING
Fix tiles in a highly polymer modified 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 Grey/White, Norcros Rapid Porcelain S1 for large format tiles.

N.B. Before grouting commences the stone should be sealed with a proprietary sealer as recommended by the stone supplier.

APPLICATION
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.

GROUTING
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.

Prime BondRapid Porcelain Tile AdhesiveRapid Porcelain and Stone AdhesiveRapid Porcelain and Stone S1 Tile AdhesiveRapid Porcelain S1 Tile AdhesiveThick Bed Porcelain and Stone AdhesiveThick Bed Porcelain and Stone AdhesiveFlexible Wide Joint Tile Grout4 Into 1 Wall and Floor Tile Grout

Movement joints in tiled installations

The various components that form a tiled installation, i.e. background, adhesive, tiles etc. all have unique physical characteristics that affect their behaviour and cause them to expand and contract at different rates when subjected to things such as moisture, changes in temperature and loading. This differential movement causes movement stresses within the tiled installation which can lead to failures such as grout/tiles cracking and tiles loosening and debonding.
The provision of movement joints help to protect the tiled finish absorbing the movement stresses. Movement joints should extend through the tiling and adhesive bed and can be formed by using suitable sealants or pre-formed movement joint profiles. Sealants are generally suitable for use in wall tiling, around the perimeter of floors and may also be used to fill inter-mediate movement joints in floors which will only be subjected to light foot traffic where neither the edge of the tiles or sealant will be exposed to high levels of impact or abrasion.

CONSIDERATION
British Standard BS 5385, the code of practice for the design and installation of internal and external ceramic, mosaic and natural stone tiles, states that the building designer should assess the magnitude of any stresses and decide where movement joints should be located. Consideration should be given to the construction materials, bedding systems, anticipated temperature and humidity conditions, areas concerned and the setting out of the tiling.
Where underfloor heating is to be used, the pipes or cables should be located to ensure the system is contained within the pattern of expansion joints. When wall tiling is planned onto mature and stable backgrounds such as existing render or plaster, the non-structural movement joints in the tiling might need to extend only through the tiling and its bed. It is essential to ascertain that the background or base is able to support the additional weight of tiling before the type of movement joint is determined. It should be noted that the use of large format tiles may result in tiles being cut to accommodate movement joints in the tiled finish.

INTERNAL WALLS
In accordance with British Standard BS5385-1:2009, movement joints should be provided:
a. Over existing and/or structural movement joints
b. Where tiling abuts other materials
c. Where tiling is continuous across junctions of different background materials.
d. In large tiled areas, at internal vertical corners and at 3m to 4.5m centres horizontally and vertically (where large degrees of thermal movement or vibration are expected, the frequency of movement joints should be increased to accommodate the movement)
e. Where stresses are likely to be concentrated, for example at changes of alignment.
f. Movement joints should be of a suitable width to permit the sealant to accommodate the expected movement (typically 6mm)

EXTERNAL WALLS
In accordance with British Standard BS5385-2:2015, movement joints should be provided:
a. Over existing and/or structural movement joints
b. Where tiling abuts other materials
c. Junctions between different background materials, where tiling is continuous across them
d. Storey heights horizontally and approximately 3m to 4.5m apart vertically; ideally they should be located over movement joints in the structural background and at structural material changes; for example, horizontal joint at top and bottom of floor slab, vertical joint at internal corners and at junctions with columns
e. External building corners, vertically between 0.25m an 1m from the corner and symmetrically wherever possible
f. At internal corners
g. Movement joints should be of a suitable width to permit the sealant to accommodate the expected movement (typically 6mm)

FLOORS—INCLUDING HEATED FLOORS
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.

HEATED ANHYDRITE/CALCIUM SULPHATE SCREEDS
In heated calcium sulphate floor screeds, movement joints should be detailed:
• Over structural joints in the underlying construction. These movement joints through the screed and tile bed should coincide with and be designed to accommodate the same movement of the underlying structural joints.
• at perimeters of floors where the screed abuts walls and up stands and at door thresholds.
• as a movement joint through both the screed and tile bed dividing the tiling into areas not greater than 40m2, or in accordance with the screed suppliers or screed manufacturers instructions. The areas bounded by movement joints should be square to rectangular with the width to length ratio not exceeding 5 to 8.
• as movement joints at significant changes of width of the screed surface and in doorways (ground plan length over 5m) with several rooms arranged one after another within a floor plan.
• as a boundary joint isolating areas of screed with separately controlled heating circuits.
• at doorway thresholds between separate areas of use.
• at junctions between heated and unheated sections of the screed.

The width and spacing of movement joints should be sufficient to accommodate anticipated thermal movement of the screed between the maximum operating temperature and expected lowest temperature of the screed. The coefficient of thermal expansion of the pumped calcium sulphate screed should be taken to be 0.012mm/m2/oC.
If the detail provided by the screed manufacturer states that there might be changes in length during installation (expansion), these must also be taken into account when calculating the necessary width of movement joints.
Note that, though pumped calcium sulphate based screeds can be laid in large areas without joints, where joints are required in heated screed they will have to be formed during the application of the calcium sulphate screed. This will require the use of formwork or the use of proprietary pre-formed movement joint profiles designed for this purpose.