• Surface Preparation
• Tiling Basics
• Installing Cladding
• Tiling Swimming Pool Walls
• Tiling Waterproofed Balconies
• Tiling Wooden Panels
• Tiling onto Existing Tiles
• Tiling onto Dry Walling
• Tiling onto Power Floated Concrete
• Tiling onto Steel
• Tiling onto Wooden Floors
• Tiling over Vinyl
• Tiling Failures

Surface Preparation

To ensure a durable, high quality professional tile installation, We recommends preparing the surface to be tiled in accordance with the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011). The trueness or soundness of the surface to be tiled can be easily and quickly checked by following these instructions.

1) The surface to be tiled needs to be clean to ensure a good bond. Check and remove old coverings like paint, gypsum plaster, bitumen adhesive etc by chipping to expose at least 80% of the surface. Wash off any dust and cement particles with a high pressure washer. Check for any fungi or mould growth and kill with an effective fungicide or a dilution of household bleach.

2) Surfaces need to be sufficiently hard to ensure they remain sound underneath the tiles. To check hardness, scratch the surface with a nail. If the nail leaves a superficial scratch then the surface is fine. Soft surfaces need to be removed and reapplied. For wall applications, ProGrip Keycoat may be painted directly to powdery surfaces to bond and seal the surface.

3) For new surfaces, ensure that the concrete / plaster has sufficiently cured before tiling i.e. the humidity of the surface must be less than 5%. This will minimise tiling failures due to shrinkage of the substrate. As a guide allow for the following periods:

i. 6 weeks for direct bedding onto new brick walls and concrete
ii. 2 weeks for tiling onto new plaster
iii. 4 weeks for tiling into new screeds

4) When tiling onto very smooth concrete surfaces like steel trowelled or off shutter concrete, acid wash the surfaces to remove laitance and rinse thoroughly with water.

5) For tiling onto existing tiled floors, make sure that the old tiles are correctly bonded to the floor by lightly tapping with a hammer or broom stick. If the tiles make a hollow sound, remove and replace these tiles with a similar tile or fill with a suitable screed.

6) The porosity of the surface will have a huge effect on the bond strength of a tile adhesive. Excessively porous surfaces will suction out moisture from the tile adhesive which will reduce the bond strength. Check the porosity of the surface by pouring water onto the surface. If the water is absorbed within a short period (

7) Check the levelness of the surface with a 2m ruler. Build up any divots with screed or tile adhesive by applying layers of ProGrip Self levelling Screed not more than 20mm thick. Make sure each layer has set before apply the next layer.

Once the necessary corrections to the surface have been completed, We recommend priming the surface as follows:

i) Make sure the surface is completely dry before priming
ii) Make a slurry by thoroughly mixing 1 part ProGrip Keycoat with 2 parts ProGrip Basecoat.
iii) Use a block brush to paint the surface to be tiled with this slurry. Make sure the coating is at least 1 – 2 mm thick and that there are no breaks in the surface.
iv) Allow to dry before tiling.

Tiling basics

A professional tiling installation that adds beauty and value requires careful preparation of the surface, the correct match between the tiles, the adhesive and the right tools.

Before Starting

Check the surface to be tiled and prepare as per the surface preparation section in this website. Make sure the surfaces are clean and free from dust. Tape over cupboards to stop dust from getting in and cover surfaces that may be damaged by falling tools or tiles e.g.counter tops

Check Your Tiles

As slight variations in colour can occur from batch to batch, make sure your tiles come from the same batch by checking the side of the box. Open a few boxes and choose and reference tile that is a match in colour and texture to the tile chosen at the store. Using this tile, check the rest for colour and texture and remove any tiles that vary too greatly (some makes of tiles are designed to have large variations – check at the store if you are unsure). Mixing and matching tiles from different boxes will often give a more uniform finish. Make sure to remove the dust at the back of the tiles with a damp cloth. This will ensure better contact between the adhesive and tile i.e. a stronger bond.

Plan Your Layout

Very few walls are straight and true so it is unwise to use the corners to provide a line to align the tiles to be laid. Rather use the centre point of the area to be tiled by measuring the middle of each wall, drawing a perpendicular line to the wall on the opposite wall. This will divide the area into quarters. Starting from the centre, lay 2 rows of tiles along the lines using spacers to ensure the correct widths. Adjust the rows to avoid narrow strips along edges to give the area a balanced look once tiled. When tiling around features (i.e. a bath, window sill etc.) adjust the reference lines to allow for a row of cut tiles around the feature. Remember that the reference lines affect the whole area to be tiled so take time to plan well

Laying Tiles

When tiling walls and floors, it is a good idea to start with the walls to prevent damaging the newly tiled floors. Mix the bag of adhesive thoroughly as per the directions on the back of the bag. This will ensure the correct consistency and proper adhesion. Do not mix too much adhesive at a time as bond strengths reduce rapidly if the adhesive stands too long and begins to set. Use the correct notched trowel to apply the adhesive. Only apply enough adhesive to lay 4 – 5 tiles at a time to make certain that the adhesive does not dry out. Use a twisting action to bed the tile into the adhesive and ensure good contact. If the tiles have uneven backs, butter the backs with adhesive prior to bedding to eliminate any hollow points. Use spacers to keep the distances between tiles consistent. Once the adhesive is reasonably dry and the tiles are firmly in place, remove the spacers and the excess adhesive from between the tiles. Clean the tiles with a damp sponge to remove all excess adhesive before its sets completely.

Grouting and Cleaning

Make sure all the excess adhesive has been removed from between the joints during the installation of the tiles. This adhesive is extremely difficult to remove once set. Let the tile adhesive set completely before grouting i.e. 24 hours for normal adhesives or 6 hours for rapid setting adhesives Mix the grout as per the directions on the back of the bag to ensure the correct consistency. Too much water will cause the grout to crack and sag once set. Press the grout into the joints with a grout squeegee using a criss-cross action making sure that the joints are completely filled. Smooth the grout and work away excess grout with the squeegee. Do not leave to get hard. Allow the grout to set for between 1 and 2 hours before cleaning with a damp (not wet) sponge. Leave the grout to set for 24 hours before polishing the tiles with a soft dry cloth (Please note a wet cloth will not remove the thin film of grout from the tiles.)

Installing Cladding

Before starting the stone or cement cladding installation, ensure that the surface is properly prepared

• New plaster walls need to be properly cured, hard and well bonded to the underlying brick work.
• Previously painted surfaces need to be chipped to expose 80% of the substrate.
• When installing onto brickwork or for heavy stone cladding, We recommend priming the surface by painting on a slurry made from 2 parts ProGrip Basecoat and 1 part ProGrip Key Coat.
• The recommended adhesive for this application is ProGrip Cladding Adhesive. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched wall trowel.

Tiling Swimming Pool Walls

With new pools, the concrete shell must be allowed to fully cure before tiling (i.e. allow for at least 6 weeks before tiling).

• When tiling over a cementitous rendering (e.g. marblelite) allow at least 3 weeks for curing.
• Ensure that the surfaces are clean and free of all traces of laitance, efflorescence and any other surface contaminants i.e. oil, dust, etc.
• For previously painted surfaces, completely remove all traces of the paint.
• In the case of concrete shells, prepare the surface by painting on a slurry consisting of 1 part ProGrip Key coat to 2 parts ProGrip Basecoat. Allow to dry before tiling.
• The recommended adhesive for swimming pool tiles is ProGrip - Tile on Tile. Thoroughly mix the 20Kg bag of adhesive with 5 litres of ProGrip Bonding Liquid and apply using a notched floor trowel.
• The recommended adhesive for pool mosaics and for grouting is ProGrip Stone and Glass Mosaic Adhesive. Mix the 5 Kgs bag of ProGrip Stone and Glass Mosaic Adhesive with 1.75 litres of ProGrip Bonding liquid and apply as per the instructions on the bag.

Tiling Waterproofed Balconies

As most waterproofing systems are incompatible with cement based tile adhesives, we recommend applying a screed above the waterproofing system prior to tiling.

• Ensure that the balcony is clean, dry and free from dust and loose particles.
• Prime the surface by painting on a slurry consisting of 1 part ProGrip Key Coat to 2 parts ProGrip Basecoat. Allow to dry before applying a screed.
• The screed must be at least 50mm thick and be allowed to fully set before tiling (minimum of 28 days).
• Before tiling, the screed should be clean, free of laitance and other surface contaminants. Make sure to install movement joints in the screed over any structural or cold joints in the balcony.
• The recommended adhesive for this application is ProGrip Flexibond for ceramic tiles or ProGrip Porcelain Fix for porcelain tiles. For both, the 20 kg bag of adhesive should be thoroughly mixed with 5 litres of cold water and applied using a notched floor trowel.
• It is very important to allow for differential movement in all tiling applications so the inclusion of tile panel movement joints, structural movement joints and perimeter joints is essential.
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 20 Kg’s bag of ProGrip Waterproof Grout with 5 litres of cold water and apply as per the instructions on the bag.

Tiling Wooden Panels

• Due to the inherent flexibility of these systems, We recommend tiling only if the walls are firmly braced. Wooden panels need to be sanded down to remove all traces of polish, wax, etc. Clean the surface to remove any dust.
• The recommended adhesive for this application is ProGrip Flex. This is a ready mixed product and can be applied using a notched wall trowel as per the instruction on the bucket. Ensure that excess adhesive is removed from between the joints as the tiles are installed
• Allow for at least 24 hours for the adhesive to fully cure before grouting. Mix the 5 Kg bag of ProGrip Waterproof Grout with 1.5 litres of water and apply as per the instructions on the bag.

Tiling Onto Existing Tiles

• Before starting the installation, check that the existing tiles are firmly bonded to the substrate by lightly tapping the tiles with a broom handle. Any hollow or loose tiles must be removed and the resultant gap filled with a screed or retiled. Allow sufficient time for any repairs to completely set before continuing.
• To ensure a good bond, We recommend acid washing and then neutralising the existing tiles to remove all traces of dirt, grime, etc. Check for any residual polish, grease or oil residues and remove with a suitable degreasing compound if necessary.
• The recommended adhesive for this application is ProGrip - Tile on Tile. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched floor trowel. We strongly recommend installing perimeter expansion joints and movement joints over structural joints as per the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011).
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 20 Kg bag of ProGrip Waterproof Grout with 4.8 litres of cold water and apply as per the instructions on the bag

Please note that due to their friable nature, We do not recommend tiling onto natural stone tiles (i.e. limestone, sandstone etc.)

Tiling Onto Dry Walling

• Gypsum dry walling is a difficult surface to tile but it is possible to create a durable tiled finish with proper care. Problems will be experienced if excessively heavy tiles are used or if there is excessive flex in the dry wall.
• As with all installations, the gypsum dry walls must be properly prepared. Previously painted wall must be well sanded and cleaned. Wall papers must be removed and the wall sanded to remove the wall paper adhesive.
• Prime the surface by painting on a slurry made from 2 parts ProGrip Basecoat and 1 part ProGrip Key and allow to dry before proceeding.
• There are two adhesives suitable for installing ceramic tile in this application. ProGrip Flex is ready-mixed product which is applied with a standard notched wall trowel or ProGrip Flexibond which is a standard cement based adhesive that must be mixed with 5 Lt of water.
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 5 Kg bag of ProGrip Waterproof Grout with 1.5 litres of cold water and apply as per the instructions on the bag.

Tiling Onto Power Floated Concrete

New concrete floors must be allowed to fully cure before tiling to ensure that any movement due to shrinkage does not affect the tiling (i.e. allow for at least 4 – 6 weeks before tiling).

• Ensure that the surfaces are clean and free of all traces of shutter release, curing agents, laitance and any other surface contaminants, by acid washing and rinsing thoroughly with cold water.
• Prepare the surface by painting on a slurry consisting of 1 part ProGrip Key to 2 parts ProGrip Basecoat. Allow to dry before tiling.
• The recommended adhesive for ceramic tiles in this application is ProGrip Flexibond. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched floor trowel. We strongly recommend installing perimeter expansion joints and movement joints over structural joints as per the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011).
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 5 Kg bag of ProGrip Waterproof Grout with 1.5 litres of cold water and apply as per the instructions on the bag.

Tiling Onto Steel

Due to the inherent flexibility of steel panels, We only recommend tiling if the panels are well braced at maximum of 300mm intervals.

• Prior to tiling the panels must be sanded or wire-brushed to remove any surface contaminants and roughen the surface. Prime the surface with a suitable anti-corrosive paint and allow to dry completely before proceeding.
• Prepare the surface by painting on a slurry consisting of 1 part ProGrip Key Coat to 2 parts ProGrip Basecoat. Allow to dry before tiling.
• The recommended adhesive for this application is ProGrip - Tile on Tile. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched floor trowel. We strongly recommend installing perimeter expansion joints and movement joints over structural joints as per the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011).
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 5 Kgs bag of ProGrip Waterproof Grout with 1.5 litres of ProGrip Bonding Liquid and apply as per the instructions on the bag.

Tiling onto Wooden Floors

• With parquet floors, check that the wooden tiles are securely bonded to the substrate and remove any loose or hollow units. Repair any gaps with ProGrip Self Levelling Screed.
• Once it has been established that the wooden floor is firm, the surface needs to be sanded down to remove all traces of polish, wax etc. Clean the surface to remove any dust.
• Prepare the surface by painting on a slurry consisting of 1 part ProGrip Key Coat to 2 parts ProGrip Basecoat. Allow to dry before tiling.
• The recommended adhesive for ceramic tiles on this application is ProGrip Flexibond Adhesive. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched floor trowel. ProGrip strongly recommends installing perimeter expansion joints and movement joints over structural joints as per the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011).
• Allow for at least 24 hours before grouting. Ensure that all of the adhesive has been removed from between the joints. Mix the 5 Kgs bag of ProGrip Waterproof Grout with 1.5 litres of ProGrip Bonding Liquid and apply as per the instructions on the bag.

Tiling over Vinyl

We do not recommend tiling directly onto vinyl tiles. The vinyl tiles must first be completely removed and the floor chipped to expose at least 80% of the concrete substrate.

• Prime the surface by painting on a slurry made from 2 parts ProGrip Basecoat and 1 part ProGrip Key Coat and allow to dry before proceeding.
• Use a suitable ProGrip adhesive recommended for the type of tiles to be used. For assistance, contact ProGrip sales staff. Thoroughly mix the 20Kg bag of adhesive with 5 litres of cold water and apply using a notched floor trowel. We strongly recommend installing perimeter expansion joints and movement joints over structural joints as per the SABS code of practice for the design and installation of ceramic tiles (SANS 10107:2011).
• Allow for at least 24 hours before grouting. Ensure that all the adhesive has been removed from between the joints. Mix the 5 Kg bag of ProGrip Waterproof Grout with 1.5 litres of cold water and apply as per the instructions on the bag.

Tiling Failures

To understand tenting, one must first appreciate that each of the various components within the flooring system are continuously expanding and contracting and that this movement places constant stress upon the tile adhesive to keep the system together. In a successful application, the sum total of the stresses is weaker than the tensile strength (bond strength) of the adhesive. However, in failed system, these stress forces build up over time to eventually exceed the bond strength of the adhesive. The tiles pop up (or tent) because there are actual changes to the linear dimensions such that the length of the tiles is longer than that of the substrate

What causes the movement

The largest source of movement comes from the shrinkage of the concrete substrate as it cures. Internationally accepted values are between 1 mm/meter for a high quality, well designed concrete and up to 3 mm/meter for a lower spec concrete. The amount of shrinkage is determined by a number of factors like the type of cement used, the mix design and the water/cement ratio. As a general rule, the cheaper the mix, the greater the shrinkage. Also, since the rate of contraction slows as the concrete ages, the time between the placing of the concrete and the laying of the tiles is important in determining the stress upon the flooring system. The shorter this period (i.e. in fast track building), the greater the stress on the system. The stress from the contracting concrete substrate is compounded by the tendency for ceramic tiles to expand. The most common and largest cause is thermal expansion. As the room is heated by the sun or heaters, the ceramic tiles start to expand as they heat up. However, as ceramic tiles are not good conductors of heat the concrete substrate is much cooler and therefore expands at a much slower rate. The SABS standard for locally manufactured ceramic tiles (which meets the AIIa European specification) will, according to international literature, have a thermal linear expansion rate of approximately 0.3 mm/meter.

Another source of expansion is irreversible moisture expansion. This type of expansion is often misunderstood and only occurs when certain types of crystalline structures of clay are present in the body of the ceramic tiles. When these crystals come into contact with water, they react with it and swell which in turn increases the size of the tile. Tiles that are prone to irreversible moisture expansion also have massive problems with the stability of their glaze as they tend to craze i.e. form small cracks on the surface of the tile. As this is huge quality issue for ceramic tile manufacturers, irreversible moisture expansion is very closely monitored and therefore a very rare phenomenon. Tiles that meet the AIIa European specification will have an irreversible moisture expansion of less than 0.01 mm/meter which negligible when compared to other sources of movement. Since each component moves at different rates and sometimes in opposite directions, the movement creates sheer within the thin adhesive bed. When the sheer force exceeds the tensile strength (bond strength) of the adhesive de-lamination occurs.

What are the factors affecting the bond strength of a tile adhesive?

The maximum bond strength is determined by the mix design of the tile adhesive. The more cement and additives used (i.e. the more expensive), the stronger the bond will be. Bond strength, however, is also proportional to amount of contact between the tile surface and the adhesive i.e. if the maximum bond strength of the adhesive is 1 N/mm2 and only 50% of the tile surface is in contact with the adhesive due to poor bedding or skinning. Then the actual bond strength will only be 0.5 N/mm2 . Thus poor application technique can dramatically reduce bond strength. Another important factor is the porosity of the tiles or the substrate. If the porosity is high, moisture is sucked out of the tile adhesive which results in partial hydration of the cement and a weaker strength development of the bond. This is an increasing problem in South Africa with people trying to contain building costs by reducing cement content in concrete floors and plasters. Low cement content equals increased the porosity. It is important to note that a strong bond is only part of the solution. From a theoretical point of view, the sheer stress in a system with a rigid tile (i.e. a vitrified tile) and a brittle adhesive (i.e. non polymer modified) can go as high as 8 N/mm2 which is eight times higher than the bond strength of a top-end European C2 tile adhesive i.e. using more flexible polymer modified adhesive can dramatically reduce the stress in a system.

What are the factors that can be manipulated to reduce the sheer stress within a tiled floor to acceptable levels?

As discussed previously the greatest contributor to the sheer stress is the concrete and its rate of shrinkage. The easiest way to counter this is by ensuring the concrete is given sufficient time to cure before tiling. The SABS standard calls for a minimum period of 28 days from the laying of the concrete and tiling. With fast track building this period can often not be adhered to. In this case, the bond strength and the flexibility of the system must be increased to handle the higher stress. The most common methods would be to:

1) Use a high quality flexible adhesive instead of a contractors grade
2) Increase the strength / flexibility of a contractors grade by mixing with a bonding liquid instead of water
3) Apply a basecoat / keying agent slurry to the substrate prior to applying adhesive and tiling

The ambient conditions and characteristics of the installation are important, especially the potential for large temperature fluctuations. Dark coloured tiles on a north facing external balcony will expand and contract significantly more than a light coloured tile in a south facing room. Temperate fluctuations also explain why winter is known as “popping season” in the South African tile industry. In winter, the difference between the maximum and minimum temperatures is at its highest and consequently tile expansion and contraction is also at its highest. This effect is further compounded by people using heaters, fires and underfloor heating to warm rooms. The size of the tile is another parameter which affects sheer stress. As the tile size increases so does the sheer stress in the system. This is evidenced by the fact that as the size of tiles has increased in recent years, so has the incidence of tenting. Once a tile is above 500mm x 500mm, the use of a flexible polymer modified adhesive is recommended. As mentioned earlier the quality of the application is vitally important. A good quality tiler can make a poor quality adhesive work while a poor quality tiler will make the highest quality adhesive fail. As discussed, contact between the tile and adhesive must be as high as possible – no less than 80% of the surface of the tile must be bedded into the adhesive. Another important factor is the thickness of the tile adhesive bed under the tile. Once the bed thickness drops below 4 mm the sheer forces increase above the tensile strength of an entry level European C1 tile adhesive. In the South African context, this is often the result of incorrect trowel choice or excessive bedding by tilers trying to extend the adhesive and maximize the amount of m2 tiled per bag. The European standard for the application of tile adhesives calls for a thin layer of adhesive to be applied first with the flat side of a notched trowel. Thereafter additional adhesive is applied and raked with the notch side of the trowel. This procedure ensures that the bed thickness is at least 4 – 5 mm.

Another common error found locally is when the excess tile adhesive has not been removed from between tiles prior to grouting as per the SABS standard. Tile adhesive is relatively hard and it tends to transfer sheer stress from one tile to another. This results in huge sheer in the middle of the tiled room and tenting.

A properly designed grout is softer and more flexible to allow it to act as a cushion to help reduce the transfer of sheer. This is, however, only half the story as sheer stress also increase as the joint width decreases. With butt jointed tiles, 100% of the sheer is transferred from tile to tile but less than 10% is transferred if the joint width is larger than 4 mm. There is a trend towards smaller joints but clients must be informed that this will increase the risk of an adhesion failure in the project. One of the more important application practices to reduce sheers forces is the installation of perimeter and intermediate expansion joints. Expansion joints break the transfer of sheer across the floor resulting in lower stresses at the centre of the panels.

Since expansion joints localize failures to within the panels, repair work is quicker and more cost effective as the areas to repair are smaller.

Why the clean break?

In a tenting failure, the ceramic tile usually comes clean off the adhesive bed leaving an imprint of its backing. This is often misinterpreted to be a sign of a poor quality adhesive. It is, in fact, an indication of a high strength but brittle adhesive. The concrete and tile adhesive both have cement as the binder and so they bond very easily together. However, since ceramic tiles are made from clay, the bond between it and the cement in the adhesive is usually fractionally weaker. The point of failure or cleavage plane the will always occur at the weakest point in the system. With a tenting failure, there is a sheering action between the tile layer and the substrate bond which places stress on the tile adhesive layer which in turn, breaks down the adhesive at its weakest point. Hence the observation of the tile coming clean off the adhesive bed. Another common type of failure is when the adhesive comes clean off the substrate and remains stuck to the tile. Since the cleavage plane is at the weakest point in the bond, this is a clear indication of poor surface preparation (i.e. tiling onto a dusty floor or not applying a basecoat slurry to a steel floated floor).