Tiling with Resin-Agglomerated and Mesh Backed Tiles

What is a Resin Agglomerated Stone?

Resin agglomerated tiles have become an increasingly popular choice of floor finishes over the last 20 years, as they offer a cost effective alternative to natural stone. These tiles are manufactured in an array of colours and are ‘engineered’ to have some improved mechanical and physical properties such as scratch resistance and flexural strength. Resin agglomerated tiles are sometimes called reconstituted or re-composed stone and in the US are known as Engineered Stone.

A resin agglomerate stone tile is a composite material, based upon the use of recycled natural stone aggregates or stone pieces which are then bound together at the manufacturing stage using a synthetic resin. The resin bound stone is then formed by vibration and compression under a vacuum to form large blocks. These blocks are then allowed to cure before being sawn into slabs, calibrated to the correct size and thickness, polished, then accurately cut into the required tile sizes.

The agglomerated stone to resin binder ratio has a direct affect upon the physical, mechanical and performance properties of the tiles. For example, use of quartz or granite agglomerates produce in general a harder wearing tile with increased resistance to acidic chemicals when compared with those based on marble agglomerates. Two main types of polymer resin binder are used in the tile manufacture and these are either epoxide or polyester.  Typically the ratio of resin binder to agglomerates varies from 5% to 7% (with 95% to 93% Agglomerate). The higher the percentage of resin present; then the greater the abrasion resistance is reduced. This is especially evident with increases in the Coefficient of Thermal Expansion of the tile.

Thermal Movement

The use of underfloor heating or undertile heating is increasingly popular as a heating choice within the UK. It can often provide cost effective, comfortable and unobtrusive heating. When considering a rigid tile finish, either directly onto a heat source or in areas where thermal gradients exist i.e. areas subjected to direct sunlight. It is important to understand how the heat change affects the different materials employed within the tiling assembly.

Materials may undergo dimensional changes when subjected to heat fluctuation. This is known as the Coefficient of Thermal Expansion. When considering the tile, the tile adhesive and the substrate, the Coefficient of Thermal Expansion for a typical constructional sub-floor such as concrete or cement; sand screed is similar to a cementitious based tile adhesive. However a resin agglomerated stone tile has a higher Coefficient of Thermal Expansion in comparison. In simple terms the tile has a high modulus of rupture, or measure of strength before rupture, and is being ‘restrained’ by the tile adhesive. However due to heating and cooling cycles, a relatively small amount of heat expansion and contraction can exert a high level of stress on the restraining layer i.e. the tile adhesive. The larger the tile dimensions, the greater the magnitude of the dimensional changes on resin agglomerated stone caused by the thermal expansion or temperature increases.

Moisture Movement

It is important to note that resin agglomerated stone tiles do have varying degrees of moisture sensitivity which means that these tiles can be susceptible to differential moisture expansion. This can often lead to a potential ‘curling’ of the tiles. The Tile Association (TTA) technical document on Tiling with Resin Agglomerated Tiles recommends that:

Cementitious floor screeds to receive resin agglomerated tiles should be completely cured and tested to ensure that they have a moisture content of not more than 2% by weight or 75% relative humidity using the appropriate test equipment and also that an appropriate adhesive is chosen” (Clause 3.5 Moisture Sensitivity).

Simply put, the use of a cementitious based tile adhesive or screed will introduce moisture directly beneath the resin agglomerated stone tile which may be taken up slowly by the tile. Some loss of moisture will occur whilst the tile joints remain unfilled; however this process will be slower. The tiles are available in various size formats including large formats (i.e. with one edge length 600mm or greater) up to typically 1200mm x 1200mm. The larger the tile in size, the more likely that moisture will become trapped at the tile/adhesive interface. In the case of some resin agglomerated tiles, this will increase the risk of curling of the tiles away from the tile adhesive bed. Therefore the correct selection of tile adhesive is essential.

For this reason, resin agglomerated tiles are not recommended for use infrequently wet areas e.g. areas of total immersion such as swimming pools or pool area walls and floors.

 Adhesive Selection

Resin agglomerated tiles are classed as neither ceramic nor strictly speaking a natural stone, being as previously discussed as a ‘manufactured’ or ‘engineered’ stone tile.

However, British standards code of practice BS 5385: Part 5: 2009 and floor tiling Design and installation of terrazzo, natural stone and agglomerated stone tile and slab flooring – Code of Practice offers the following recommendations in clause 11.2.1 of BS 5385::Part 3 2014: “To avoid moisture from the adhesive bed distorting resin-based agglomerated stone, reaction resin adhesives, or quick drying low alkalinity cement-based adhesives should be used”.

BAL manufacture suitable rapid drying, low alkalinity tile adhesives. Dependent upon the background substrate to which the tiles will be fixed, BAL POURABLE ONE mixed with BAL ADMIX AD1 may be used for floors or BAL RAPID FLEX ONE with BAL ADMIX AD1 for walls. Where the resin agglomerate stone is especially moisture sensitive use of a suitable reaction resin tile adhesive i.e. BAL EASYPOXY AG may be specified.

Adhesive Application

When installing a ceramic tile or natural stone tile using a tile adhesive, the accuracy of a sub-floor should be such that when placing a 2 metre straightedge on the floor that there is no gap greater than 3 mm. This is known in BS 5385 Part 3 2014 as SR1 (Surface Regularity).

If this is not the case, this may be rectified by the use of a suitable smoothing and levelling compound such as BAL LEVEL MAX, dependent upon the type of floor construction.

In the case of the installation of large format tiles, in particular resin agglomerated stone tiles, the surface regularity should be SR1 or better for both wall and floor substrates.

The tile adhesive should be applied using a suitable notched trowel to the wall or floor and in the case of large format tiles, additional back buttering of the tile with the tile adhesive may be required to ensure adequate adhesive coverage.

When fixing resin agglomerate tiles to both walls and floors solid bed fixing is essential to;

  1. Ensure, as far as is practicable, full contact is achieved between the tile adhesive and the wall or floor tiles,
  2. Eliminate voids beneath the tiles, which in floors are potential points of weakness under load and in wet areas, moisture may become trapped from the service conditions on site or during regular cleaning.

Environmental Consideration

As previously discussed, resin agglomerated tiles are not recommended for use in frequently wet areas e.g. areas of total immersion such as swimming pools or pool area walls and floors.

For domestic showers and wet rooms, generally it is important to seek further advice from the tile supplier or manufacturer with respect to their fitness for purposes in these applications. It is also important to establish what, if any, additional precautions may be necessary to take both during and following completion of the tiling installation. Fundamentally the wall and floor should be protected from moisture ingress/ leaks using a suitable waterproofing tanking system such as BAL TANK-IT.

Additional protection from potential water ingress may be afforded by the use of a suitable impervious reaction resin grout such as BAL EASYPOXY AG or BAL FLOOR EPOXY. However, as stated in BS 5385-Part 4: 2015: “The use of impervious grouts and adhesives is no substitute for a tanked installation” (clause 7.2.3 Installations not immersed but subject to occasional wetting, note 2).

It is also important to note that the fixing of resin agglomerate stone tiles is not recommended for external tiling using a tile adhesive. Where the tile is deemed to be suitable for use for external application by the supplier or manufacturer, for external facades they should always be installed using appropriate mechanical fixings.

The Importance of Movement Joints

The need for inclusion of movement control joints within any tiled installation is well documented in the BS 5385: Parts 1-5 suite of standards. Fundamentally movement from factors such as drying shrinkage movement, thermal and moisture movement (as discussed previously) will generate stresses within the tiling system which can lead to de-bonding or cracking of the grouting and/or tiles.

Where the resin agglomerate tile is deemed to be suitable for floors subjected to direct heat or heat from an environmental source, The Tile Association technical document Tiling with Resin Agglomerated Tiles recommends the frequency of movement joints needs to be increased. For example, BS 5385-3 advises that for floors subjected to significant thermal changes, tiles should be divided into bays of size not greater than 40m² with an edge length not greater than 8m. In order to allow for the anticipated increase in thermal expansion of the resin agglomerated tile installation, the bays of size of the movement not greater than 25m² with an edge length not greater than 6m.

Under normal dry internal conditions, the advice is that bay sized should be reduced to bay sizes not exceeding 36m² (100m² bays for ceramic tiles).

Mesh Reinforced Resin Backed Tiles

There has been an increase in recent years in the number of natural stone tiles i.e. marble or granite imported into the UK which has a mesh reinforced resin backing bonded to the lower interface of the stone.

Typically the resin polymers commonly used for this are epoxide, polyurethane or polyester of which polyester is the most commonly used. A fibre mesh is often embedded within the resin coating i.e. a fibreglass mesh.

The reasons for this vary from providing additional strength to the stone, particularly in the case of thin marble, limestone or granite, or sometimes it may be designed as a ‘temporary’ backing.

Unfortunately a polyester resin will have a much higher Coefficient of Thermal Expansion compared with the stone itself. Coupled with the surface of the resin which has a ‘waxy surface’ and may contain free styrene monomer, these will act as barriers to adhesion.

When fixing these mesh reinforced resin backed stone tiles, the bond strength achieved is totally dependent upon the quality and consistency of the resin/ mesh backing applied to the stone. This applies to both the dry and wet duty test conditions.

Factors which influence this are, for example;

  1. The tensile bond strength between the mesh reinforced resin backing and the stone, which can vary from strong to very weak.
  2. The chemical type of resin used e.g. polyester resin has a high coefficient of thermal expansion when compared with different types of stone and differing backgrounds/base.
  3. Variability in the quality and application of the mesh and resin between the same stone i.e. where mesh is not completely encapsulated in the resin or when the mesh is weakly bonded to the resin itself.

However the most fundamental factor when considering the feasibility of the use of a cementitious based tile adhesive conforming to the requirements of BS EN 12004: 2007 + A1: 2012 is that the tile adhesive is no longer bonding directly to the stone but to an intermediary (and potentially weaker) layer which has been introduced between the stone and the tile adhesive.

As an alternative to cementitious tile adhesives, reaction resin adhesives conforming to BS EN 12004: 2007 + A1 2012, could also be considered. However the use of a resin based i.e. an epoxide tile adhesive would prove to be very difficult, particularly where elevated temperatures may exist on site. In addition the amount of restraint offered to the mesh reinforced resin backed stone may counter-act against the anticipated levels of movement within any tiling installation, in particular where, for example any thermal and moisture movement is prevalent.

BS 8000: Part 11 Workmanship on building sites Part 11: Internal and external wall and floor tiling – Ceramic and agglomerated stone tiles, natural stone and terrazzo tiles and slabs, and mosaics – Code of Practice recommends that: “With large tiles and slabs any reinforcing mesh should be well adhered to the underside, and the mesh and adhesive should not obscure more than 25% of the underside of the tile or slab unless they are mechanically fixed”.

This advice mirrors that previous recognition is given for mesh backed mosaics which adhesives that the combination of mesh and glue holding the mesh in place should;

  1. Not cover more than 25% of the back of the tesserae
  2. Be no deterioration in the backing material and its glue whilst in service
  3. Be compatible with a cementitious tile adhesive in accordance with mosaic suppliers’ recommendations.

In conclusion, where a mesh reinforced resin backed stone is specified, unless the tile adhesive is able to bond directly to the stone to produce a contact area of 75% or more, it may be possible to consider removing the mesh reinforced resin backing altogether, but this must be undertaken following consultation with the stone supplier or manufacturer.

If this is not feasible to remove the backing without damaging the integrity of the stone, then consideration should be given to mechanically fixing. In the case of external wall cladding, BS 5385: Part 2 2015 advises that “Stone tiles which are resin mesh backed should not be used”.

 

 

Mosaics – it’s all in the prep!

Available in various shapes, sizes and textures, mosaic tiles come in beautiful designs that can create a stunning centre piece or flash of inspiration for a tiled project.

There are three different mosaic types – ceramic, glass and natural stone – and each can be formed into a sheet using mesh-backing, paper or plastic sheet face or glued tessera.

If you are tiling with a mesh-backed product, it is advisable to check the suitability of the mesh by immersing the product in water. If the glue breaks down or is visible over the majority of the mosaic, you may need to reconsider the product you are using. This is because British Standards state that the mesh should not exceed more than 25% of the surface area of the mosaic.

The key to a successful project using mosaic tiles is in the preparation, setting out and fixing. Preparation of the background to SR1 (surface regularity) is vital because final adjustment of tiles is very difficult. SR1 is a maximum of 3mm of deviation over a 2m straight edge.

If you need to build the walls out to achieve SR1, then it is advisable to use a render such as BAL Quickset Render. A pre-blended rapid setting polymer-modified cement:sand mortar, it is ideal for fast track installations and patch repairs as tiling can be carried out in just two hours.

With a working time of 30 minutes it can be used from 2mm up to a maximum of 20mm with normal rendering practices.

The most common background you’ll be tiling to is probably plaster. If it’s new, you should allow 4 weeks drying time, before brushing with a stiff bristle brush and priming with BAL Prime APD.

If the surface is plasterboard you can fix directly, and there is no need to prime when using flexible cement-based adhesives.

You can also tile with mosaics over existing tiles. Ensure that the surface is flat and true, check for soundness – if there are any hollow sounding tiles, these should be removed. Wash down the surface and fix directly such as BAL Max Flex Fibre.

Cement-boards and other tile backing boards – such as BAL Board – are also extremely good surfaces to tile to. Ensure that the boards are securely fixed with adhesive or at 300mm centres. Use appropriated tape over the joints.

Please be aware that British Standards now state that plywood and other wood-based sheets are not suitable as a wall tiling background. This is partly due to the poor quality of plywood on the market – and the proliferation of readily-available, cost-effective tile backerboards which are more dimensionally stable than ply.

When tiling with mosaics in a wet area, water sensitive backgrounds – such as plaster or plasterboard and some tile backer boards, will need to be waterproofed (or tanked).

This will conform with British Standards which state: “The use of impervious grouts and adhesives is no substitute for a tanked installation.”

BAL has several products which can be used for protecting backgrounds including BAL Tank-it – a two-part tanking kit that is dry and can be tiled in two hours. Ideal for shows and wet rooms, it is even suitable in total immersion areas such as swimming pools, spas and fountains.

As well as preparation, setting out is also crucial for a quality installation. What you don’t want is misaligned mosaic sheets! Fix your sheets using a minimum 3-4mm notched trowel, place the sheets in rows and beat into place using a grout float or hard rubber float. Always stagger the sheets (half bond) but maintaining joint alignment. Once applied, paper face sheets can be removed approximately 2 hours later.

When fixing with mosaics you can either use cement-based adhesives such as BAL Max Flex Fibre or BAL Rapid-Flex One, or more preferably opt for a ready-mixed adhesive such as BAL White Star Plus which is perfect for mosaic sheets.

BAL White Star Plus is brighter and whiter in colour – perfect for the application of translucent glass tiles and mosaics. A lighter, smoother formulation makes for easy cut out and application. Highly flexible, it is formulated with Fibre Strand Technology (FST) giving it extended open time of 30 minutes and more strength.

If you’re not keen on a ready-mixed product, you could always opt for a cement-based product like BAL Max-Flex Fibre. Slow setting in 16 hours, it allows more time to fix tiles and adjust them on the wall. Also, white and with a smooth mix, it makes for easy application for glass tiles and mosaics.

Before grouting any mosaic installation, it may be necessary to protect the tiles against grout staining with a protective sealer. This protects the tiles during the grouting process and can easily be cleaned off after grouting.

The best grout for use with mosaics is a product made with very fine sand such as BAL Micromax2. A fine grout is required, particularly with metallic or glass mosaics, so the surface isn’t scratched.

BAL Micromax2 is flexible, water and frost resistant and is formulated with Microban built-in anti-microbial and anti-mould technology. It is also efflorescence free – meaning no nasty salt stains.

If you want a truly waterproof and hygienic protection, then an epoxy grout like BAL Easypoxy AG is recommended. Extremely durable, BAL Easypoxy AG provides a smooth finish and is easy to clean. This product may also be used as an adhesive for certain background types and environments.

To finish your project, use a sealant such as BAL Micromax Sealant for all internal corners, perimeter joints and movement joints.

For technical advice and support with your mosaic project, call BAL Technical Advisory Service on 03330 030160.

(FIRST PUBLISHED IN TOMORROW’S TILE AND STONE)

A guide to sub floor preparation

Self-levelling floor compounds help level up small surface irregularities on new and existing bases and usually come in one-part or two-part forms. Easily mixed and simple to apply, they find their own level giving a smooth finish for laying tiles or other floor coverings.

Most levelling compounds can only be applied up to 30-40mm and will need to be used in more than one application or with other materials required. However there are some exceptions on the market such as BAL Level Max which can be applied from 2 mm up to 80 mm in one application.

It’s always important to remember that levelling compounds are never suitable as a finished, wearing surface, and that they should always be covered.

Typically; self-levelling compounds are suitable with most screeds, including sand:cement, anhydrite and flooring grade asphalt. However, when levelling timber floors, or screeds containing underfloor heating then only fibre-reinforced products are suitable i.e. BAL Level Max. Remember to check the products you’re using with the manufacturer to make sure they’re suitable.

Before laying a levelling compound it is essential to ensure that correct preparation of the sub floor is carried out.  Firstly ensure that the surface is clean, firm, dry and free from grease, dust and any other contamination which may be considered barriers to adhesion.

Any new concrete or screed must be left to fully cure according to the manufacturers’ instructions before applying any levelling compound. Ensure that any direct-to-earth sub-floors incorporate an effective damp proof membrane.

The majority of subfloors will also need priming. Floors such as concrete, cement:sand screeds, anhydrite screeds, cement:sand screeds with underfloor heated screeds and suitably constructed suspended timber floors.  Priming ensures that the levelling compound fully adheres to the substrate.  If levelling over timber boards where the joints are open, we would suggest using thin heavy duty tape to bridge the gaps.

When mixing your self-levelling compound always ensure you follow the manufacturer’s instructions. Typically, products like BAL Level Max are mixed by adding powder to clean water five parts powder to one part clean cold water by weight. We would always recommend mixing with an electric drill mixer at a slow speed i.e. under 300rpm.  Always mix until a lump-free mortar is achieved and allow the mixed leveller to stand for two minutes before re-mixing for 30 seconds.

Once the required consistency is achieved, pour the mix over the prepared substrate and spread to the required depth using a suitable steel finishing trowel or long handled blade. Work the mixture well into the corners, edges and around projections. When you’ve finished spreading the mixture on the floor, pour some more mixture onto the floor and spread that out and blend it in with the previous area.

Before allowing to cure, ensure that the surface is sufficiently smooth to receive floor coverings without any further treatment. If you are laying tiles or slabs, floors should be corrected to SR1 (Surface Regularity) – this is plus or minus 3mm or less over a two meter straight edge. We would not recommend the use of spiked rollers on a fibre-reinforced product (e.g. BAL Level Max) as this can pull fibres through to the surface. If any trowel marks do remain, rub down before the compound has hardened.

Always allow the new floor to set before laying your finished floor surface. Setting times can vary depending on your chosen product normally between 4 to 24 hours and is dependent upon your floor finish. For example, BAL Level Max can be tiled after 4 hours, but must be left to set for 24 hours for other finishes such as vinyl or carpet. This is to ensure that the covering is fully protected from any moisture in the screed which will diffuse through the screed and damage the surface if not left to fully cure.

In wet areas allow a minimum of 24 hours before waterproofing the levelled screed with a tanking system such as BAL Tank-it. Suitable for use internally or externally, BAL Tank-it is a rapid-dying cementitious waterproofing system. It can be tiled in 90 minutes and no priming or matting is required. Thanks to its EN Classification BS EN 14891, BAL Tank-it is suitable for a wide range of projects including total immersion such as swimming pools.

It can be easily applied with only a brush, roller or trowel and as well as providing outstanding performance, like BAL Level Max, BAL Tank-it comes with full back-up technical and on-site project support and a written 25 year guarantee for complete peace of mind.

One should always remember that self-levelling compounds, such as BAL Level Max, are not a substitute as a wearing surface.

Finally, we would always advise checking with the manufacturer or their technical advisors for before application to ensure project success.

At BAL our Technical Advisory Service is fully equipped to provide support to contractors, architects and tilers using levelling compounds – including NBS M40/M10/M20 specification assistance, on-site consultancy and expert technical advice.

Contact BAL Technical Advisory Service on 0845 600 1 222 or our Innovation and Technology Centre for training enquiries on 01782 591120.

Covering the whole of the UK, BAL Product Support Technicians offer practical knowledge and on-site consultancy and training to tiling and flooring contractors.

If you’ve experienced a problem on your installation whatever brand you’ve used, you can trust our PSTs to offer dependable solutions and remedies.  What’s more, we’ll even send samples away for independent analysis at our laboratories to find the cause of the problem.

 

By David Wilson, 

UK Head of Technical Standards and Information at BAL

Protecting tiles with a DPM

With the number of planning applications for basement extensions rising by 183% according to research by Halifax, tilers need to be aware of the potential for moisture issues that can cause a floor to fail.

Adhesive failure, staining, discolouration and efflorescence can all occur due to moisture emanating from the subfloor, so it is essential that the final finished tiled floor is protected from the damaging effects of moisture from below with a Damp Proof Membrane (DPM)

Surface damp proof membranes, like new BAL DPM, will protect tile adhesive and tiles from both ground floor water and residual construction moisture found in new screeds such as sand: cement and calcium sulfate screeds.

As a rule of thumb, to achieve a moisture content of 0.5% water by weight (Carbide Bomb test) the drying time for a calcium sulfate screed – is approximately 1mm per day up to 40mm thickness under ideal site condition. Direct to earth cement: sand screeds will also require a DPM.

One solution is BAL DPM which acts to control moisture and allows for the early application of a levelling compound or tile adhesive.

BAL DPM can be applied onto a new cement: sand screed once the moisture content is below 98% RH as measured using an hygrometer. BAL DPM can be applied to new calcium sulfate screed   once the moisture content is below 87%.  Please note, it is important to obtain the screed manufacturer’s confirmation that the screed is compatible with a DPM and does not contain any additives that may reduce adhesion between the screed and the DPM.

Before laying the DPM, ensure that all screeds are well-prepared and flat, with any laitance removed.

As well as basements and cellars, a DPM should also be considered for other projects where a structural damp proof membrane is not present or is ineffective. This is likely to be the case in refurbishment projects involving buildings constructed pre-1970, where the installation of an effective structural damp proof membrane was not a requirement of the building regulations.

BAL DPM is also suitable for balconies, terraces and patios which are due to be tiled, dependent upon design consideration. A DPM on an external tiled area will protect moisture sensitive stone such as granite from staining due to rising ground floor water, as well as rain water. For external tiled areas, we would always advice on the use of a capillary passive drainage system like BAL’s new external tiling systems which ensure the rapid drainage of tiled surfaces.

As well as external areas, BAL DPM can be used in industrial installations that require resistance against dilute chemical spillages or pollutants such as chemical plants or manufacturing units.

Unlike other DPM systems, BAL DPM is also suitable for walls, as well as floors, as it is resistant to hydrostatic pressure. Refer to the Technical Data Sheet for detailed application instructions.

Waterproofer and Primer

As a multi-purpose product, BAL DPM can also be used as a one coat primer or as a two-coat waterproofing system.

When sand-blinded, BAL DPM allows tiling onto difficult substrates such as steel.

As a waterproofer, BAL DPM is an easy two-coat system when used with BAL Self-Adhesives Butyl Tape in corners and junctions.

With the number of planning applications for basement extensions rising by 183% according to research by Halifax, tilers need to be aware of the potential for moisture issues that can cause a floor to fail.

Adhesive failure, staining, discolouration and efflorescence can all occur due to moisture emanating from the subfloor, so it is essential that the final finished tiled floor is protected from the damaging effects of moisture from below with a Damp Proof Membrane (DPM)

Surface damp proof membranes, like new BAL DPM, will protect tile adhesive and tiles from both ground floor water and residual construction moisture found in new screeds such as sand: cement and calcium sulfate screeds.

As a rule of thumb, to achieve a moisture content of 0.5% water by weight (Carbide Bomb test) the drying time for a calcium sulfate screed – is approximately 1mm per day up to 40mm thickness under ideal site condition. Direct to earth cement: sand screeds will also require a DPM.

One solution is BAL DPM which acts to control moisture and allows for the early application of a levelling compound or tile adhesive.

BAL DPM can be applied onto a new cement: sand screed once the moisture content is below 98% RH as measured using an hygrometer. BAL DPM can be applied to new calcium sulfate screed   once the moisture content is below 87%.  Please note, it is important to obtain the screed manufacturer’s confirmation that the screed is compatible with a DPM and does not contain any additives that may reduce adhesion between the screed and the DPM.

Before laying the DPM, ensure that all screeds are well-prepared and flat, with any laitance removed.

As well as basements and cellars, a DPM should also be considered for other projects where a structural damp proof membrane is not present or is ineffective. This is likely to be the case in refurbishment projects involving buildings constructed pre-1970, where the installation of an effective structural damp proof membrane was not a requirement of the building regulations.

BAL DPM is also suitable for balconies, terraces and patios which are due to be tiled, dependent upon design consideration. A DPM on an external tiled area will protect moisture sensitive stone such as granite from staining due to rising ground floor water, as well as rain water. For external tiled areas, we would always advice on the use of a capillary passive drainage system like BAL’s new external tiling systems which ensure the rapid drainage of tiled surfaces.

As well as external areas, BAL DPM can be used in industrial installations that require resistance against dilute chemical spillages or pollutants such as chemical plants or manufacturing units.

Unlike other DPM systems, BAL DPM is also suitable for walls, as well as floors, as it is resistant to hydrostatic pressure. Refer to the Technical Data Sheet for detailed application instructions.

Waterproofer and Primer

As a multi-purpose product, BAL DPM can also be used as a one coat primer or as a two-coat waterproofing system.

When sand-blinded, BAL DPM allows tiling onto difficult substrates such as steel.

As a waterproofer, BAL DPM is an easy two-coat system when used with BAL Self-Adhesives Butyl Tape in corners and junctions.

For detailed application instructions as a primer and waterproofing please refer to the BAL DPM Technical Data Sheet.

For more information on new BAL DPM including how-to videos and technical information, visit www.bal-adhesives.com/newproducts

 

 

Selecting the right cement-based tile adhesive

When selecting the right tile adhesive for your tiling project, a number of factors need to be taken into account including the substrate, type and size of tiles and the environment.

 

Selecting the wrong adhesive for the intended background/application could lead to unwanted consequences including the cracking or de-bonding of your tiles, causing you financial pain in repair and recompense.

Purely selecting an adhesive or grout on its BS classification is not always the be-all – as other factors may render your selection invalid.

Firstly, let’s look at the substrate or background.  Whether you’re tiling onto tile-backer boards, tongue & groove floorboards, sand: cement screeds or even existing tiles will make a massive difference as to what adhesive to consider.

For example, where floors need to resist some limited movement or vibration, then a flexible/deformable adhesive should be selected

Polymer modified adhesives/grouts have the addition of either powdered polymers, pre-blended in at the manufacturing stage or can be modified with a liquid polymer additive.  This enhances the physical and mechanical properties of the product.

One such example is BAL’s new Rapid-Flex One wall and floor tile adhesive. Fast, strong and flexible, BAL Rapid-Flex One is an all-round adhesive which provides a number of benefits to fixers including extended 30 minutes open time and 60 minutes working time (pot life) giving total control. What’s more, it is still ready to grout in just three hours – ensuring fast track project completion.

BAL Rapid-Flex One is enhanced with Fibre Strand Technology (FST) providing enhanced strength and a super smooth consistency for easier and faster spreading. With S1 classification – meaning it’s deformable – BAL Rapid-Flex One comes in just one white colour meaning it can be used for any tile type at the great value of a standard grey flexible adhesive.

Tile type and size also plays a significant factor in determining your adhesive and grout. Ask yourself “are my tiles porous?”, or are they glazed, fully vitrified, light-coloured/translucent or natural stone. Is the material you are using vulnerable to water-staining? Are you using large format or mosaic tiles and are they mesh-backed?

For example ready-mixed adhesives may be suitable for porous-bodied ceramic tiles, but for porcelain a highly polymer-modified cementitious adhesive would be recommended. Ready-mixed adhesives are also not suitable for floor tiling or for tiles over 300x300mm.

In case of light coloured or translucent natural stone, rapid-setting and drying white cementitious adhesives – such as BAL Rapid-Flex One – are recommended in order to minimise any potential risks of staining. A pourable adhesive – such as new BAL Pourable One – may also be suitable for floor tiling with large format tiling.

This is because they can be build up to large bed depths – up to 25mm in one application for Pourable One – when using uncalibrated stone or for patch repairs.

A new and improved alternative to BAL Stone & Tile PTB, it has all the same great benefits and is also available as just a white adhesive – meaning that only one bag is needed for any floor installation.

A highly flexible adhesive, it is particularly suited with underfloor or undertile heating as it resists thermal movement.

While BAL Rapid-Flex One and BAL Pourable One are suitable for most tiling installations, sometimes you need a little bit more flexibility and deformability when tiling to specialist substrates such as tongue & groove floorboards, single layer chip or plywood floor, floating timber floor, steel, epoxy coating and existing glazed tiles.

This is where you need a specialist tile adhesive such as BAL Single Part Fastflex. A one-part elastomeric adhesive, BAL Single Part Flexible is manufactured with rubber-crumb technology meaning it is highly deformable (S2) as well as sound-deadening, helping to achieve the requirement of Building Regulations Part E (Resistance to sound).

There are other factors which should be considered and more importantly are NOT covered by the tile classification. Some of these include ease of use, coverage, colour, pot life and adjustment time and cost.

 

Keeping tilers and contractors fixed up with the latest techniques

As the first adhesive manufacturer to open a specialist training centre in 1992 for standards and fixing techniques, BAL understands that quality workmanship is paramount to an installation.

BAL Demo

Since it began to offer training courses to help tilers and flooring contractors maximise their skills, more than 100,000 people have received training from BAL with more than 16,000 people trained at a BAL training centre.

In fact since the company opened the doors to its new Innovation and Technology Centre (ITC) in Stoke-on-Trent in March 2015, nearly 2,000 people have been trained at the new site.

Complete with 40-seat auditorium (with standing viewing platforms), practical training bays, breakout areas and meeting rooms, the new facility leads the way in training and development in tiling and flooring.

Dave Rowley, Training Manager at BAL, said: “I believe that training is vital to the continued success of the company and the industry in general.

“Maintaining high standards and fixing techniques helps to prevent poor practices and incorrect specifications which can have a negative impact for all in the industry including manufacturers, distributors, specifiers, contractors and fixers.

“At BAL training is a key priority, which is why we have invested in our Innovation and Technology Centre to give everyone in the industry the opportunity to learn about the latest technologies and installation practices to enhance their skills.”

BAL provides a full range of training courses for apprentices, fixers, contractors, and distributors. BAL’s training is endorsed by The Tile Association (TTA) andthe Construction Industry Training Board (CITB) while the company has also been highly commended by the National Training Association (NTA).

BAL’s training courses aim to cater for a wide range of needs, from experienced  professionals looking to up-skill with new techniques, to inexperienced professionals or apprentices. Key courses include:

·         Introduction to screeds and subfloor preparation – a practical course on preparing, laying and rendering floor screeds.

·         Preparing and tiling timber floors – demonstrations and practical training on preparation/levelling, fixing and grouting to single layer timber, plywood and floating timber floors.

·         Preparing and tiling to anhydrite screeds – practical and theoretical training on preparing and tiling to anhydrite or calcium sulfate screeds, including the use of uncoupling systems.

·         Preparing and tiling to under tile heating – practical and theoretical demonstrations on preparing and tiling to undertile or under floor heating systems.

·         Tiling and grouting for hygiene or chemical environments – including the use of epoxy adhesives and grouts.

·         Preparing and tiling wetrooms – in-depth course on waterproofing/tanking wet rooms, fixing, grouting and essential products.

·         Introduction to adhesives and grouts – foundation level course on cementitious and ready-mixed adhesives and grouts, basic fixing techniques for inexperienced tilers/apprentices.

·         Five day wall and floor tiling course – introduction to preparation, setting-out, fixing and cutting of wall and floor tiles and including grout and finishings.

BAL also provides bespoke courses to suit individual training needs, for example, the company recently held a special one-day course for mosaic mural artists, and thanks to the flexibility of the ITC, more bespoke courses like this can be held at the centre.

A new course on the company External Tiling Solutions for balconies, ground-floor terraces and roof terraces has also been launched and is available to book through BAL Product Support Technicians (PSTs).

Launched this year, BAL’s External Tiling Solutions uses proven technology from sister company Gutjahr, which protects outdoor covering against the unpredictable British weather and diverse extremities such as rain, frost and heat.

Gutjahr System Technology from BAL offers designers and contractors innovative drainage, ventilating and uncoupling solutions for cantilevered balconies, roof terraces and ground terraces.

The one-day training course for tilers and contractors provides an overview of the system, practical demonstrations and theoretical presentations.

Those completing courses at BAL receive a certificate of completion, plus merchandise and product worth more that the course.

To find out more about BAL’s range of training courses and to book yourself a place visit www.bal-adhesives.com/training or call 01782 591100.

[FIRST PUBLISHED IN TOMORROW’S TILE AND STONE]

Getting the natural look with stone tiles

Throughout history, natural stone has been used as a building material, and to this day it continues to be used as a wall and floor cladding.

Natural stone has a timeless beauty that comes in a wide range of colours, sizes and textures. It also has practical qualities, providing a durable surface that will look good for years to come, making it a favourable choice for commercial and domestic installations.

Installation of natural stone is a matter of knowledge and balance; the knowledge to identify the variables that can affect i.e. adhesion to a suitable substrate, and the ability to get the right balance between the stone, the substrate, and the environmental conditions to which the stone will be subjected to on site and in service.

Granite, limestone, marble, travertine, sandstone and slate all have different physical properties and correct selection of a suitable tile adhesive is very important, dependent upon where the stone is being installed

The first consideration when tiling with natural stone is making sure your background is prepared correctly in accordance with the recommendations given in British Standards BS 5385: Part 1 (internal walls) ) Part 5 (includes Natural stone and slab flooring) and Annex E of  BS 5385 Part 3 (underfloor heating).

New concrete must be air dried for at least 6 weeks before tiling, while new sand:cement screeds need a minimum of three weeks. If you’re in a hurry, there is always the potential to use a quick-setting product, such as BAL Quickset Cement as replacement for Portland cement in cement:sand screeds that you can tile on in just 24 hours (4 hours for bonded screeds) or use BAL Flexbone 2Easy a floating uncoupling mat that can go on new screeds that are walkable. Plus with Flexbone 2Easy no preparation is required under the mat.

Before tiling onto calcium sulfate screed, it’s important that all laitance is removed after 2-6 days, and the floor is fully dry with moisture levels less than 75% relative humidity (0.5% CM). This can take anywhere from  40 – 80 days depending on thickness. Drying time is approximately 1 day per mm up to 40mm, and 2 days per mm for  screeds greater than 40mm. Alternatively you can use new BAL Flexbone 2Easy which can be laid direct to an anhydrite screed at 1.5% CM.

If you’re tiling onto a screed that incorporates underfloor heating, there are more considerations before fixing can commence. For sand:cement screeds a minimum of 3-week drying period should be followed by a slow warming of the screed: about 5oC per day up to the maximum operation where it needs to be held for three days, or as per the heating manufacturer’s recommendation. Then allow it to cool, preferably with the heating off, or turned down below 15oC if the weather’s cold. A pre-warm up should also be considered for other backgrounds with underfloor heating, including anhydrite screeds. If commissioned, temperature should be gradually increased by 5°C per day approximately 7 days after initial drying until the maximum required working temperature is reached. This should be maintained for a minimum of one week, before being gradually reduced to around 15-20°C.

For heated floors use of suitable uncoupling matting, such as BAL Rapid-Mat or BAL Flexbone is recommended for applying stone tiles onto heated screeds.

For new walls, don’t expect to fix over new Portland cement:sand render before at least 2 weeks’ drying – unless you’ve using BAL Quickset Render or similar, which sets in two hours at 20°C.

No such waiting, though, if boards – such as new BAL Board –  are the background substrate.  But you must check that the stone tiles (plus adhesive) aren’t going to be too heavy.  On gypsum plasterboard, for example, the limit is 32kg/m² – typically 10mm thickness for stone is the maximum. For other proprietary boards, such as lightweight tilebacker boards and glass reinforced cement boards, check with manufacturer as they may able to cope with heavier weights. With BAL Board, the weight limit is 100kg/m², making it perfect for use with natural stone tiles.

When installing  natural stone with tile adhesives, special attention should be given to your choice of adhesive. Some carbonate-based stones, such as marble, travertine and limestone, may be susceptible to drawing in residual moisture from the tile adhesive, which has the potential to cause problems. If this happens there is a strong risk of the stone being stained or watermarked. Furthermore, excessive residual moisture has the potential to react with certain minerals (such as iron oxides) and organic deposits in the stone, which could discolour the face of the tile. For certain types of stone use a rapid-setting white cement based adhesive such as BAL Rapid-Flex One.

When using large format un-calibrated stone, to achieve a flat tiled surface, it is advisable to use a thick-bed pourable adhesive, such as BAL Pourable One. Trusted pourable products can offer bed thickness up to 25mm, and can be grouted after three hours due to fast-setting properties. The cement chemistry in this product uses up more of the water during hydration, thereby reducing water that could cause staining or reducing the likelihood of water staining.

Some types of ‘green’ stone, can become dimensionally unstable when wet.  Always fix these with a resin-based adhesive – for example, an epoxide resin type R1 or R2 to BS EN 12004: 2007+A1 2012.

Importantly, when fixing, don’t ever consider spot fixing natural stone tiles. “Dob & Dab” fixing is the cause of many installation failures. As with ceramic tiles, when fixing in wet duty areas or on floors, they must have a solid bed of adhesive to ensure all voids beneath the stone are eliminated.

When tiling natural stone, solid-bed fixing should be adopted to achieve 100% bonding at the back of the tiles. Back buttering of a tile is recommended with uneven stone and/or large format tiles. Alternatively  a suitable pourable flexible adhesives may alleviate the need for back buttering with large format stone and can help to speed up project time when floor tiling.

The risk of spoiling the effect of natural stone is greatest when the grouting stage is reached.  It’s generally wise to choose a grout colour that is similar to the stone tile colour – particularly with porous stone..

On very porous stone, the result can be a rough ‘picture frame’ effect around stone edges, unless tiles are sealed with a suitable sealer.  The risk is also reduced by using reputable cement-based grouts containing a water-retaining agent, or by use of a rapid setting grout.

When grouting natural stone, it’s advisable to carry out a trial on a small area to determine the risk of staining. When in doubt, use a suitable protective sealer and repeat the trial to ensure a satisfactory result is achieved.

Finally to ensure installation success, it’s important that movement joints are incorporated in the floor tiling. For perimeter joints, a suitable neutral curing silicone or similar is generally advised in movement joints for stone tiling. That’s because acid curing sealants (e.g. acetoxy silicones) are bad news for some types of natural stone, especially marble and limestone.  They chemically react with carbonates in the stone causing de-bonding at the edges.

In high traffic areas, however, avoid sealant movement joints should be avoided altogether because they won’t prevent stone edge damage. In these cases, proprietary pre-formed movement joints are recommended.

Overall there is a lot for fixers to consider, but by taking the appropriate steps at each stage, there is no reason why the beauty of a natural stone finish cannot be successfully installed and maintained for years to come.

For technical advice and training that can be trusted, contact BAL Technical Advisory Service on 03330 030160 or our Innovation and Technology Centre on 01782 591120.

By David Wilson, UK Technical Services Manager

(First published in Tile and Stone Journal)

Tiling onto Calcium Sulfate (anhydrite) screeds

Calcium Sulfate or anhydrite screeds have grown in popularity over the last decade as they offer substantial benefits over traditional sand:cement screeds.

Anhydrite screed web

Easy to lay, low cost, fast-drying, pumpable, self-levelling and offering minimal shrinkage, anhydrite screeds are perfect for domestic or commercial projects. They are also suitable for underfloor heating so long as the pipes and associated heating elements are covered with at least 25mm of screed.

However, despite the numerous benefits associated with anhydrite screeds, fixers and installers need to aware of potential problems.

These types of screeds contain anhydrous (dry) Calcium Sulfate and aggregates instead of a cement-based binder. The binder comes as either an alpha hemi-hydrate (a stronger and harder crystalline form) or anhydrous Calcium Sulfate. When water is added the binders will form calcium Sulfate dihydrate – more commonly known as Gypsum. This reaction stops when the vast majority of the Calcium Sulfate binder is used up and is generally complete after a period of 3-7 days, leaving the remaining water to evaporate through the surface of the screed.

Before laying onto Calcium Sulfate screeds it is vital to ensure that the moisture content is at the correct level for the required floor finish. Typical values for moisture sensitive floor finishes are less than 0.5%  Water by Weight  or less than 75% relative humidity (RH) for impermeable floors and less than 1% w/w for more permeable floors. When fast-track tiling is required consider the use of a Damp Proof Membrane such as BAL DPM. BAL DPM can be used on anhydrite screeds up to 87% RH.

As a general rule thumb the drying time for a Calcium Sulfate screed, so the moisture content reaches 0.5% w/w, is approximately 1mm per day up to 40mm in ideal drying conditions – i.e. air temperature of 20C with a relative humidity not greater than 65%. Drying times will significantly increase for thicker screeds or those in poor drying conditions.

Accelerated drying of Calcium Sulfate screeds may be used once the screed is at least 7 days old. It is at this point that we would recommend commissioning any underfloor heating. The system should be increased by approximately 5°C per day until the maximum required working temperature is reached or as per the underfloor heating manufacturer’s recommendations. This should be maintained for a minimum of one week, before being gradually reduced to around 15-20°C. Do not exceed a temperature of 55°C. Use of dehumidifiers will also help.

Before laying tiles or other finishes onto Calcium Sulfate screed one of the most important tasks is the removal of laitance.

Laitance is a weak layer of fine particles deposited on the surface of the screed as the anhydrite cures. This layer is too weak to tile onto and can also inhibit  drying  of the screed. Many of the failures we see are as a result of contamination of the adhesive by laitance – highlighting the importance of carrying out this step.

Laitance should be removed by light abrasion using a suitable sanding machine i.e. a rotary floor scarifier and a 60’s grit sandpaper. Remove excess dust completely with a vacuum cleaner. Abrading the surface is best carried out 4-6 days after the application of the screed and can assist in the drying out process. Scarifying the surface is even recommended with low laitance Calcium Sulfate/anhydrite screeds as this further aids adhesion.

All traffic should be kept off the screed until it has hardened sufficiently in accordance with the screed manufacturer’s instructions and should always be protected from contamination and damage from other trades. It is best to protect the screed fully until the flooring is applied using boarding.

If not protected as the project progresses it may result in the wearing or grinding down of the screed’s surface. If this does occur then further surface treatment may be required. Moisture should also be avoided as any reintroduction of water can result in damage to the screed integrity and may affect any installed heating pipes.

Before tiling we would recommend applying a primer to the prepared screed surface before application of the tile adhesive. Priming created an effective barrier and assists in making the surface more stable.

When selecting your tile adhesive, consideration should be given to factors such as the tile type, and the type and method of cleaning the floor whilst in service – i.e. how wet the finished floor may become and what are the risks associated with limited water penetration. Slow or rapid-setting tile adhesives can be used, depending on the tile type and environment.

When the adhesive is cured, the joints between the tiles should be filled with a suitable grout – please note that a minimum of 3mm for floor tiling is recommended.

For ceramic tiling movement joints will be required in these installations. Any movement joint, or joints likely to be subject to movement, in the Calcium Sulfate screed should coincide with the movement joints in the tile bed. Movement joints should be incorporated as outlined in British Standard BS 5385-3, 2014 Clauses 6.8 and 7.1.6. For heated screeds also refer to The TTA technical document Tiling to Calcium Sulfate based screeds

Last, but not least, before tiling onto Calcium Sulfate screeds we would always recommend getting professional technical advice from manufacturers to ensure your installations look great and last the test of time.

By David Wilson, UK Technical Services Manager

(First published in Contract Flooring Journal)