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General specification for fixing glazed ceramic floor tiles or  porcelain tiles onto existing floor tiles on interior surface beds and suspended slabs

Please note that ‘general’ specifications are issued for information purposes, and should not be used as project specifications.  

As each and every project needs to be assessed individually on its own merits and characteristics please contact the TAL Technical Advice Centre for a project-specific detailed materials and methods specification for specific projects.  

It is important that the tile selected is suitable for the application, preferably against a written Supplier’s specification.  Factors such as water absorption, irreversible moisture expansion, MOR and PEI ratings, chemical resistance and overall stability of the product need to meet the requirements of the service conditions.  

The backs of all tiles must be clean and free from dust and contaminants.

Please note that any “wet” areas, such as showers or balconies, should be waterproofed using TAL SUPERFLEX I or TAL SUPERROOF waterproofing compounds prior to commencing tiling.  Please feel free to contact us for a specification for waterproofing and tiling these areas, as well as for technical literature on any of our products.

 

TAL PRODUCT REQUIREMENTS

The TAL products required for this installation are as follows:

TAL KEYCOAT 

TAL GOLDSTAR 6

TAL BOND / TAL BOND POWDER

TAL WALL & FLOOR GROUT

NOTCHED TROWELS

SPACERS

TAL SEALMASTER CORD

TAL GOLDSTAR SEALMASTER 1000

 

Special note must be taken of the following:

Existing Tiles:

For this application it is imperative that the existing tiles are in good condition and firmly attached to the background, ie are not damaged, loose or hollow-sounding.  All cracked, damaged, loose or hollow sounding tiles must be removed prior to the new tile installation.

Adhesive System:

We have specified the use of TAL GOLDSTAR 6 rapid setting high strength adhesive for the installation of these tiles.  However, if timing allows for a quick-setting adhesive option, then TAL GOLDSTAR 12 can be considered.   

The advantages of using TAL GOLDSTAR 12 are as follows:

It is however important that newly installed tiles are protected from traffic (other trades, etc) for a minimum of 12 hours, while the adhesive sets.   This is especially important in fast-track installations.

Suspended Applications:

Tiling onto SUSPENDED concrete slabs require special precautions to be taken as the installation is prone to increased movement caused by slab deflection and creep, loading on the slab, etc. TAL BOND or TAL BOND POWDER needs to be incorporated in the adhesive and grout mix, or a single part flexible adhesive such as TAL GOLDFLEX needs to be used to allow for the increased movement.

NOTE: All Ground Floor levels with Basement / Parking levels below should be construed as SUSPENDED slabs.    

Tile Panel Movement Joints & Perimeter Joints:

It should be noted that the lack of movement joints in a tile panel, or poorly constructed joints,  is a major cause of tile failure.  Joints must be created at the required spacing and must be well raked out to remove all traces of adhesive residues, debris, contamination, etc, ie the joint must extend through the tile and tile adhesive layers. These joints must be filled with TAL GOLDSTAR SEALMASTER 1000 Polyurethane Joint Sealant (and suitable backing cord where applicable) in accordance with the manufacturer’s instructions.

(See later detail of correctly constructed tile panel movement joint and perimeter joint.)   

 

  • BACKGROUND PREPARATION
    • For this application it is imperative that the existing tiles are in good condition and firmly attached to the background, ie are not loose, damaged or hollow-sounding. 
    • The existing tiles should be acid washed and neutralised in accordance with the manufacturer’s instructions to remove all traces of dirt, grime, polishes and sealants etc.  The tiles should be inspected and any residual polish, sealant, grease or grime residues should be removed using a degreasing compound in accordance with the manufacturer’s instructions. The background must be clean, dry, firm and sound and free from dust, loose particles and all traces of surface contaminants before proceeding.
    • All damaged, cracked, loose or hollow-sounding tiles must be removed, as well as the existing fixative, to expose the underlying substrate, which must be firm and sound .  These areas can then be filled so that they are flush with the adjacent tiles using TAL RAPIDFIX*.  The remedial work must be allowed to cure completely (approximately 12 – 24 hours, depending on application thickness and ambient conditions) before proceeding.
    • Key the surface with a slurry consisting of 1 part  TAL KEYCOAT to 2 parts  TAL KEYMIX powder or 2 parts  TAL GOLDSTAR 6 or  12 powder (by volume), which is applied by block brush.  Allow this slurry coat to dry for 4 – 6 hours before applying the adhesive.
      • ADHESIVE SYSTEM
        • Surface Beds
          • Apply TAL GOLDSTAR 6 rapid-setting adhesive to the background using a notched trowel.
        • Suspended Slabs
          • Apply TAL GOLDSTAR 6 rapid-setting adhesive mixed 20kg with 5 litres of TAL BOND (replacing the water in the mix) to the background using a notched trowel.
            Alternatively, TAL BOND POWDER may be added to the adhesive mixing water at a ratio of 1 x 1kg sachet per 20kg TAL GOLDSTAR 6, or TAL GOLDFLEX single-part flexible rapid-setting adhesive may be used.  When using TAL GOLDFLEX no additives are required, simply mix with clean water, alleviating possible mixing errors on site.
        • General
          • In this tiling situation it is imperative that there is a solid bed of adhesive at least 6mm thick beneath each tile.   We would recommend the use of a notched FLOOR TROWEL.
            NOTE: Back buttering with a thin coat of adhesive may also be required when using large format tiles to ensure full contact and a solid bed of adhesive behind each tile.
          • At no time spread more adhesive than can be tiled onto in 10 – 15 minutes.  Depending on atmospheric conditions, this will normally be around 1 square metre.  This prevents the adhesive from drying or “skinning” before the tiles are applied.
          • Bed dry tiles (do not soak) firmly into the wet adhesive  with a twisting action to ensure full contact between the background, tiles and adhesive.  Tiles should be well tapped home with a rubber mallet or the wooden handle of a trowel.  It is sound practice to remove the occasional tile to ensure that good contact has been achieved.
          • When using heavily lugged tiles, or tiles with a very irregular back profile, it is good practice to butter the back of each tile, ensuring that the grooves or dovetails are completely filled with adhesive.
          • Clean off any surplus adhesive remaining on the face of tiles and between the joints with a damp sponge before the adhesive dries.
          • Never butt joint tiles.  Joints are required to allow the individual tiles to move with respect to each other and thus avoid a compressive stress build-up.  They are also required as vents for the tile adhesive to cure.  The joints between ceramic floor tiles must be a minimum of 5mm wide, and a minimum of 3mm wide between porcelain tiles. 
          • Pot life of the adhesive will vary with climatic conditions.  Under no circumstances should adhesive which has been left standing for too long be reconstituted by adding more liquid.
          • Do not tile over structural, expansion or cold joints in the background.  These joints must be extended through the various layers to the surface.

     

      • GROUTING
        • Grouting must not be carried out until sufficient bond has developed between the bedding mix and the tiles to preclude disturbance of the tiles during the grouting operation.  Allow a minimum of 4 hours before grouting.
        • Surface Beds
        • Suspended Slabs
        • General / WARNING :
          • Particular care must be taken to clean the grout off the tile face before it hardens completely.  This is especially important when an additive such as TAL BOND or TAL BOND POWDER has been used.
          • A sample of the tiles to be used should be tested beforehand to ensure that no grout is absorbed through the glaze, or into the tile body, causing permanent staining of the tiles.
          • It is important to use the stipulated amount of liquid in the TAL Grout mixture.  When cleaning, a damp, not wet , sponge must be used.  Over hydration (too much water) of the mix, or in cleaning, causes colour variations in the grout joints, and also affects the integrity of the grout, resulting in a friable product.

     

    • MOVEMENT JOINTS
      • It should be noted that the lack of movement joints in a tile panel is a major cause of tile failure.  They should be specified at the design stage to avoid placing  them in heavy traffic areas and spoiling the visual effect of the tiles.
      • Movement joints should be located in both directions at maximum 5 metre centres for interior surface bed applications, and maximum 3 metre centres for suspended applications.
      • Movement joints should also be located around the perimeter of all floors, in all vertical corners, against obstructions fixed to the structural background and over all discontinuities in building materials, e.g. at interfaces of concrete and brickwork.  In addition, movement joints should be located around any fixtures protruding through the tiled surface such as columns or stairs.
      • The joints should be at least 5mm wide and extend through the adhesive and  tile layers.  All construction / cold joints and structural joints in the background must be extended through the adhesive and tile layers to the surface in the form of voided joints /  tile panel movement joints.  With regards to structural joints, the full width of the structural joints must be respected and extended through the adhesive and tile layers to the surface.
      • All tile panel movement joints and construction / structural joints in the existing tile installation must be identified and must be maintained through the new tile installation.
      • In areas where tile layouts do not allow for this, the existing tile panel joint sealant material (resilient joint sealant and backing cord, if applicable) must be removed, and these joints filled, using TAL RAPIDFIX or TAL GOLDSTAR 6.  The tile panel movement joints in the new installation must then be carefully cut through the existing / underlying tile and tile adhesive layers, so that the joint extends from the face of the new tiles through the various layers to the substrate.   
      • It is however imperative that all structural joints in the existing tile installation are maintained.
      • Where practical, the bulk of the depth of the movement joint can be filled with TAL SEALMASTER CORD.
      • Seal the joint using TAL GOLD STAR SEALMASTER 1000 polyurethane joint sealant in accordance with the manufacturer’s instructions.  It is important that the joint sealant bonds only to the sides of the movement joint.
      • For the key requirements common to all tiling situations please refer to SANS 10107-2011, Code of Practice for the Design and Installation of Ceramic Tiling.

    Should you require any further assistance or have any queries regarding the above, please do not hesitate to contact us.  Assuring you of our best attention at all times.  

     

    Yours faithfully,

     

    SHARON MARGON

    TECHNICAL ADVICE SUPERVISOR

    TAL 1972 & 1984