Specify Wall and Floor Tiling With Confidence - ARDEX UK Ltd
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This CPD seminar aims to enable listeners to make informed choices when specifying wall and floor tiling by considering the impact that tiles, backgrounds and finished environments will have on the adhesive and grout specification. It will also demonstrate how to avoid common installation failures, through optimum product specification and guidance on best practice. Having listened to this CPD the audience should feel confident about selecting and specifying the appropriate fixing solutions in most situations.
Ardex UK Ltd History
Before commencing the CPD we just like to set the scene regarding Ardex still a family owned business Ardex group employs approximately 1600 employees across 50 sites and has global sales in excess of 450,000,000 pounds. Ardex has been at the forefront of the UK market for flooring and tiling products for 50 years, servicing the market from its manufacturing base in Haverhill Suffolk. Being ISO 9001 accredited you can rely on the fact that all Ardex products are manufactured to a recognised quality standard. We also take every appropriate step we can to minimise our impact on the environment. Our new products have been formulated to achieve greater coverage, so that less product is required during installation and serious consideration is given to the sources of raw materials we use. Ardex provides customers with quality products and a Technical Support network you can rely on. Our guiding principle is to have excellence in all that we do no matter how big or small the job. Tiles can create a perfect finish for most environments.
Not only are beautiful designs available they are also hygienic and provide a durable finish for years to come. We work closely with Association such as the tile Association, BASA, the stone Federation and the contract flooring Association, to promote professionalism technical standards and best practice within the tiling industry as documented in detail, in BS5385 and code of practice 8000.
The tile Association is a source of useful information relating to tiling, national building specification clauses provide best practice guidance phone support for your tiling specifications.
Backgrounds for tiling tiles and the situations we place styling in are constantly changing through a mix of new technology and fashion trends. Yet all these factors influence the choice of tile adhesive or grout and the specification.
Specifying Tile Adhesives
Let's firstly take a look at the basic principles of how a tile adhesive forms a bond. There are three main types of ceramic tiling adhesives dispersion, cement based and reaction resin. The first two are the most common. The reason it's worth taking a moment to talk about them is because they develop adhesion in different ways. Dispersion otherwise called ready mixed or paste adhesives are for wall use found most commonly in the DIY/domestic tiling market, they need to dry to develop adhesion. Cement based adhesives are commonly used in the contract market for both wall and floor tiling. These bagged adhesives when mixed with water form a mortar which sets and hardens. Reaction resin adhesives commonly referred to as epoxy or polyurethane are generally two component systems which react together when mixed to gain adhesion. These are used in specialist areas. This very basic principle is important as consideration such as the body of the tile type, its level of water absorption, the tile size or weight, the width of the grout joint, coupled with the porosity of the background or the end tiling situation will affect your choice when specifying; especially for dispersion or paste products.
As we continue through their CPD we'll build on to this initial framework. At the end of the day although not a visible part it's the correct choice of adhesive and correct installation that literally holds the overall project in place for years to come.
We will review the most common background and tile types and consider the challenges presented by today's tiling installations. We will discuss the solutions and how you can specify with confidence by reviewing the additional properties and opportunities that modern adhesive technology brings. A classic example of use of high performance adhesives in a demanding area is Saint David's shopping centre. These products are made to last.
Although we've addressed basic adhesion properties earlier, it's important to see that by adding additional polymers and formulating the products to suit given situations. We can develop a range of enhanced properties for adhesives and grouts for any installation. For example, we may start with a standard adhesive and modify the formulation to improve adhesion. Basic polymer modified adhesives were developed in the late 1960s. We made a start with a standard setting adhesive and developed it to make it rapid setting, in 1972.
We may need less water staining on a tile or need to reduce the risk of warping, so we use rapid drying technology. We may start with a standard adhesive but realise that we need more flexibility due to thermal expansion when tiling on to heated screeds. Ultimately, we may have even added all these elements, but we want to deliver fail safe technology and strength, so we add additional elements and develop unique microtec performance 2008. At this point it's useful to familiarise ourselves with the classifications within the European standards for adhesives and grouts.
Adhesives are firstly characterised by type for example C, D or R denoting cementitious dispersion or reaction resin. Then by their additional properties F,T,E. F denoting fast setting T is reduced slip and E is extended open time. Whether it be an adhesive or grout classification a level 1 product has normal characteristics and a level 2 product has additional characteristics. A C1 adhesive will have a minimum tensile strength of 0.5 newtons per millimetre squared, whereas a C2 will reach a minimum tensile strength of 1.0 newtons per millimetre squared. In addition to this there are also other properties such as enhanced slip, faster setting or longer open time.
It's important to point out that S2 adhesives due to the fact that they are highly deformable are not recommended for heavily trafficked areas as stated in BS 5385. We can provide further technical guidance when required.
C2 TE S1 adhesive is a cementitious adhesive with additional properties which are reduced slip and extended open time and is deformable. Quality products will reach and be classified to the EN standards. However the classifications only provide a guideline level of performance. Unique high performance fibre reinforced technology products demonstrate considerable advances on the standards and provide exceptional real life performance on site. These products designed for tomorrow but used on many sites today outperformed the standards.
Such products have even higher adhesion performance and can be classified as follows. For example C2FT TEE S1 adhesive offers a real performance advantage which is not apparent if you were just to use the EN classification as a reference is the open time on site. For example whereas a standard open time would be 20 minutes an extended open time would be referred to as 30 minutes under laboratory conditions. In real world site conditions this could be much less. Unique high performance fibre reinforced technology products outperformed this basic benchmark of 30 minutes with some having an open time of 60 minutes double that stated as extended in the classification. These are clever products easy to use and guaranteed to perform so you can specify with confidence. These unique high performance fibre reinforced technology products have been used on many prestigious projects and many difficult installations to date.
It's also important to understand the tile types available and how they will impact on your specification choice of adhesive from grout. Let's take a look at why. Although the tiling industries started fixing in sand and cement today's tiles and situations demand high performance adhesives with products and technical backup you can trust. Apart from the aesthetics of the design finish there are a number of suitability factors to consider when choosing tiles such as:
- will the background or base support the tiling? We will cover this in the common background section, consider the weight of the tyre.
- will the adhesive strongly adhere to the tile and background? Consider the tile and background properties including water absorbency.
- how appropriate are your tiles for the situation in which they'll be specified?
Apart from aesthetics it's important to consider the following factors when selecting tiles for your specification. Considered tile properties such as frost resistance, thermal shock, chemical resistance, bending strength and abrasion resistance. All glazed floor tiles are classified under a porcelain enamel Institute PEI rating for the suitability of the location relating to wear.
The tile Association can provide additional information regarding the testing of tiles as can the tile manufacturer or stockist. However slip resistance tends to be a main consideration when specifying tiling.
Taking the first point there is little guidance in the current British standard relating to slip resistance and there is no standard worldwide test. Different testing methods include the tortoise pendulum and ramp. The tile Association published a useful technical guide called the slip resistance of hard floor coverings which can be purchased from their website.
Ceramic historically in the UK the majority of standard wool tiles have glazed porous bodies with a water absorption between 10% and 20%. When glazed they are suitable for a wide range of internal applications. However due to their porosity they're not Frost resistant and should only be used in internal conditions above sub-zero temperatures.
Glazed ceramics are not generally suitable for heavily trafficked areas. Unglazed ceramics are more suitable for wet areas and are typically used in commercial situations. The body of these tiles allows some water absorption, therefore as a general rule are appropriate for fixing with dispersion adhesives dependent on size or weight of the tile. Fully vitrified porcelain is characterised by its very low water absorbency, it is extremely versatile and hard wearing. However due to its low water absorbency a highly polymer modified cement based adhesive would always be the preferred option with these tiles but in some cases, for example when specifying small wool tiles and mosaics, a dispersion product may be appropriate. Always check if in doubt.
Vitrified and porcelain tiles with water absorption less than 3% can be used in conditions subject to frost, for example exterior use. Vitrified or semi vitrified although the porosity of the tile is not as low as porcelain, we cannot rely on porosity of the materials to enable bonding, so we still need to specify a highly polymer modified adhesive here. Mosaics these are generally defined by their size rather than the body of the tile. Classed as a mosaic when the individual tesserae are less than 25mm these can be glazed or unglazed porcelain vitrified earthenware ceramic glass or natural stone. Mosaics tend to be either mesh bag or plastic or paper faced it's essential that any backing mesh and its water resistant glue does not occupy more than 25% of the area of each mosaic. The choice of tiles or mosaics for utilization in swimming pools and other submerged areas is an application which demands careful consideration prior to specification, and further guidance is provided by the tile manufacturers that TTA and in BS5835. Essentially the tiles need to be technically fit for purpose, and they should have a low water absorption of 3% or preferably less. Individual advice can be given regarding the suitability of the adhesives and the best practice application method if you need more detail when specifying mosaics. Remember that unique high performance fibre reinforced technology products are suitable for all these tile types.
Agglomerated stone previously referred to his conglomerate stone tends to look like polished granite or terrazzo. The tiles are made by mixing marble or granite chips with polyester or epoxy resin. These are important to identify as sometimes the resin can be attacked by cement and or absorb moisture which may cause the tile to expand. As with every tile type mentioned it's important to remember that unique high performance fibre reinforced technology products are suitable here.
Natural stone for the last decade the popularity of natural stone has increased. Natural stone adhesives have been formulated to address the main considerations when fixing these tiles.
Common natural stone types are travertine, marble, limestone, slate, granite all have unique considerations when specifying generally due to their chemical composition, water absorbency, size and thickness and surface texture. Some natural stone and agglomerate stone tiles are more demanding as their moisture sensitive and prone to water staining and or warping which can lead to a greater risk for the specifier. Therefore always check stone types with the manufacturer and seek guidance on fixing products. It's important to consider when specifying the grout or adhesive.
Modern rapid drying adhesives avoid this issue, for total Peace of Mind specify a rapid drying formula product. Natural stone looks beautiful when specified and installed well however we often see the effects of wrongly selected or wrongly applied product and the effect left behind.
Here we see an example of blood fixing where normal cemented he says has been used. The water from the adhesive has penetrated into the porous tile. We would never condone blog fixing as we explain later in this CPD. However the problem of water staining into the tile can be avoided by the use of rapid drive rapid drying technology adhesives and grouts designed for use with natural stone. The rapid drive formula system binds the mix water with the adhesive or grout virtually eliminating the risk of water staining, warping or distortion and thereby guaranteeing the best possible finish to all natural and agglomerate stone applications.
Although we offer a detailed separate CPD on the subject of fixing natural stone due to its current popularity, we feel it's important to highlight the need to specify appropriately designed rapid dry adhesives and grouts when dealing with this finish.
Tile Trends and Backgrounds
Tile types are constantly evolving, and fashion trends often provide new fixing challenges for porcelain, glass, natural stone, large format and ultra-thin tiles. The new ultra-thin tiles heighten technical and installation considerations when specifying. In this instance always call the manufacturer for advice.
It's also important to understand the backgrounds we need to bond our tiles to and how they will affect your specification choice of adhesive. Let's take a look at the most common backgrounds and tile adhesive specification considerations.
Always specify that backgrounds are free from debris, clean, sound, dimensionally stable, important when considering expansion and shrinkage, which can be caused by the effects of changes in moisture content. For example avoid wood based materials such as sheets and boards that expand or contract with changes in atmospheric humidity, as explained in BS5385. Dimensionally stable is also important when considering movement under loads. A lack of rigidity of the supporting background will incur unacceptable deflections under loads and impacts. Ceramic tiling is basically a rigid finish and therefore requires rigid support. Backgrounds should also be level, dry, appropriate for the given conditions. When specifying onto boards and membranes always refer to the manufacturer’s instructions. Check for surface regularity as specified in BS5385.
Any holes can be filled with rapid repair mortar. As you need a flat base to tile on smoothing compounds are an ideal cost effective way to achieve this. Some adhesives may be used for pre smoothing, although this is convenient it may not be the most cost effective method. Commonly there are two types of adhesives 2 part latex or powder and water based. Our Technical Support can provide detailed guidance. Many compounds can be pumped at the rate of 3 to 400 metres squared per hour, ideal for large projects.
All screeds must be thoroughly mixed at the right consistency by weight that’s 1 part cement to 4 parts correctly graded screeding sand, they must also be well compacted.
Bonded screed must have a minimum thickness of 25 millimetres to a maximum of about 40mm. The concrete base must be prepared, and a bonding treatment applied to ensure adequate adhesion of cement and sand screed. Unbounded screed unbounded screed must have a minimum thickness of 50mm applied to a concrete base over a slip separating or damp proof membrane e.g. polyethylene sheet or where slab cannot be prepared. Note that the uniform screed thickness is preferable so the concrete base should be reasonably flat with no steps etcetera that could lock the screed and cause cracking.
Floating screed must have a minimum thickness of 75mm, 65mm for light loads. Applied over compressible insulation materials for acoustical thermal insulation. Note that a uniform screed thickness is preferable. We have a product for every screeding situation and being renowned as the experts in fast track tiling, we can offer appropriate advice on product specifications and methods of work, which will provide you with more options than the standard recommended drying times.
Traditional screeds require a minimum of 3 weeks prior to tiling. Background shrinkage and recommended drying times can cause practical timing problems on site, with this in mind a number of rapid drying and rapid hardening screeds and renders have been formulated.
Bonded screed rapid hardening screeds.
Bonded screed rapid hardening screeds will allow installation after 3 hours, concrete base must have finished shrinking 6 weeks minimum. Unbonded screed rapid drying screeds will allow installation after 24 hours, even if the concrete base is still shrinking.
Floating screed rapid drying screeds
Floating screed rapid drying screeds will allow installation after 24 hours even if the concrete base is still shrinking. Note that some high performance screeds are only appropriate in dry locations. Rapid hardening renders will also allow tiling after just 2 hours.
Common Tiling Backgrounds
BS8000 workmanship on building sites which is currently under review contains useful information on drying times of backgrounds, surface regularity of backgrounds and the installed tiling as well as differences in height either side of tile joints. It's important to allow backgrounds to fully dry out before tiling. Here’s an audience question- what do you think happened here? Did the tiles get bigger? Or the background get smaller? The answer is the background got smaller.
Portland cement and sand screeds after 7 days curing allow at least 2 weeks drying time under good site conditions 20°C and 65% relative humidity before fixing ceramic tiles or natural stones. For gypsum base creeds allow 1 week per 10mm thickness drying time up to 40mm at a relative humidity of 65% and a temperature of 20°C.
Note drying times can be considerably extended where the above conditions do not prevail, and all the gypsum base cream thickness exceeds 40mm. For cement and sand renders allow at least 2 weeks drying time under good conditions after 1 to 2 days curing before fixing ceramic tiles or natural stones. For swimming pools allow 3 weeks drying. For concrete allow at least 6 weeks drying time under good conditions. Mass concrete structures for example swimming pool tanks may take longer to dry.
In northern Europe the statutory drying time is 6 months. For concrete block work including air rated or brickwork, allow at least 6 weeks drying time under good conditions before rendering or direct fixing the tiles. Note that have rendered the above drying times for render or plaster then apply giving a total of at least 6 to 8 weeks. Plaster check the masonry background is dry before plastering minimum 6 weeks. Plastering should be done in accordance with BS5492 and modified in BS5385 part 1 section 3.4. Then allow at least 4 weeks for gypsum based plaster to dry. Don't forget plaster is not a satisfactory base for tiling in wet locations. In these cases a waterproof coating should be applied. Some plaster walls may be painted. Check that the paint is firmly adhered generally a hard gloss paint will be able to be tiled over if firmly adhered to its background. Emulsion paints should be mechanically removed.
In addition to these standard recommendations it's worth noting that some rapid renders have been introduced which assuming that the block work or brickwork is mature or has been allowed sufficient time to dry can save up to 4 weeks drying time. Some may be tired after as little as 2 hours after application even when applied at a thickness of 20mm. Note, if the background is new and still shrinking than a rapid hardening render will be of no benefit.
In some cases a rapid hardening and rapid drying render can be installed on proprietary mesh reinforcement systems over new backgrounds so that the tiles can be installed 24 hours later. This procedure allows the background to continue to dry and shrink without affecting the applied materials.
If tiling direct to timber is contemplated all timber has to be conditioned before any tiles are fixed to it. The backs and edges of the timber must be sealed. Ensure that the timber is capable of carrying the additional load and is sufficiently rigid. To provide extra rigidity noggin should be fitted between joists as recommended in BS5385 part 3 and fix exterior grade W BP or marine grade plywood minimum 15mm thickness over existing boards screwed down at 300mm centres. Check that there is adequate ventilation and a damp proof course.
When tiling direct to tongue and groove specify the appropriate unique high performance fibre reinforced technology products. In areas subject to vibration or areas where any risk of cracking would be unacceptable then the timber background should be over sheeted with a suitable tile backing system as recommended in BS5385. We have listed the most common backgrounds here but there are more, if in doubt always seek our technical guidance.
The ideal substrate for tiling is render concrete or concrete block work, for other backgrounds guidance is given to weight limit as follows:
The maximum weight of tiling which can be supported by a dry well adhered gypsum plaster background is 20 kg per square metre i.e. equivalent to ceramic tiles with a maximum thickness of 8mm plus tile adhesive, or natural stone tiles with a maximum thickness of 7 millimetres plus tile adhesive.
The weight of tiling direct to a plasterboard background should not exceed 32 kg per metre squared i.e. equivalent to ceramic tile adhesive with a maximum thickness of 12.5 millimetres and natural stone at adhesive with a maximum thickness of 10mm.
Hence in general it's always best not to skim plaster that will be tiled. It is important to emphasise that the weights quoted include both the tile and adhesive.
The variety of situations in which tiling is specified is endless, from a domestic splashback, through to an Olympic pool or even the reptile house at London Zoo. All have issues to be considered such as where is the tiling to be installed? What would it be used for? A dry area or wet area might the tiling be subject to aggressive conditions.
With exterior use we would need to consider Frost resistance for tiles adhesives and grouts. Unique high performance fibre reinforced technology products are required for facades and exterior tiling where conditions in use can be challenging. For instance from thermal shock. You need to consider wearing of tiles load very solid bed fixing, remember that S2 adhesives are not suitable in these situations, again unique high performance fibre reinforced technology products are.
High performance flexible adhesives such as fibre reinforced technology are ideal also consider project parameters. The window of opportunity for refurbishment work is short here so rapid drying and or rapid hardening systems are essential.
Water resistant cement based adhesives and grouts will be essential to resist total immersion. Unbalanced or aggressive water can be damaging to grouts adhesives and the pool structure. We cover this area in more detail in our leisure CPD.
The recent trend for wet rooms and power showers has led to a greater need for waterproofing systems prior to tiling. The majority of wall backgrounds are moisture sensitive such as plaster and plasterboard. This coupled with high levels of water from today's power showers and complete wet room systems with the water no longer contained in a preformed shower tray, place yet more challenges on the tiling specification. There is a difference between water resistant and waterproof. Waterproof stops the transfer of water. Water resistant means the water can pass through, but it won't break the material down. Tile adhesives with enhanced properties tend to fall into the latter category and a water resistant. Therefore on their own and when used with cement based grouts, they will not hold the transfer of water to the background. Water penetration effects can be damaging to the background and lead to failures. BS5385 part 4 recommends tanking backgrounds in shower areas. To produce a watertight specification adding in a waterproof coating guaranteed to stop the transfer of water to the background easy to apply and it can be tiled on within 2 hours. As tiling in wet areas is a detailed subject, we covered this in our leisure CPD seminar.
Specifying Tile Grouts
This is the final most visible part of the fixing process and it's important to get it right. Beautiful tiles will look beautiful when grouted well. As with tile adhesive selection it's equally important to consider the parameters of the tile and the finished environment. Although dispersion or ready mix crowd tends to be popular with the DIY sector, professionals will use a cementitious or reaction resin system. Due to a number of issues relating to ready mixed grouts. A highly polymer modified grout may be required. Nowadays it's more likely that the flexible polymers are built in or added as a bottle admix. Consider water absorption levels of the tile. A porcelain tile will have very low absorption thus requiring a highly polymer modified grout to bond to the tile edges. Remember a natural stone maybe moisture sensitive there for a rapid dry technology grout should be selected. Also consider aggressive environments and whether a reaction resin grout is required.
BS EN 13888 provides classification for grouts although both types of grout so specified the most commonly used or cement based.
Reaction resin grouts are usually up oxide based and used in specialist areas such as swimming pool surrounds and specialist industrial locations. However we continue to invest our resources in research and development to innovate and invent new technologies. We have a number of exciting innovations in the pipeline which will be able to discuss in more detail in the near future.
Whether it be in adhesive or grout classification are level 1 product has normal characteristics and a level 2 product has additional characteristics as explained earlier.
But jointing of tiles is not recommended. Consider movement implications and where necessary the adhesives ability to lose water through the tile joints to form an adequate bond. BS5385 recommends the following minimum grout joints for tiles, wall 2mm floor 3 millimetres. However it's important for us to recognise that grout joints these days are much thinner than the British standard recommendation. If this is the requirement for specification, then it's essential that backgrounds and bases are dimensionally stable with no thermal movement. Finer aggregate grouts are suitable for normal joint widths of 1 to 5mm at the coarser grade aggregates from 3 to 10mm. Of course for tiles prone to scratching a fine aggregate is recommended. Nowadays modern production techniques enabled us to produce a number of grout colours to suit most tastes. Through investment in R&D we have designed formulations which retained their colour integrity and through regulated production processes raw materials and quality control systems were able to provide excellent colour consistency across the range. A useful tool when specifying is a grout colour selector which clearly demonstrates the finished colour for your tile specification. We've covered the key considerations relating to the tile choice background preparation and adhesive and grout selection. Now let's take a look at best practice advice regarding installation techniques.
An essential part of any tiling project is the correct specification of movement joints. Guidance on where to install a movement joint is detailed in BS5385 parts 1 2 and 3. Essentially movement joints should be installed over existing or structural movement joints, where tiling abouts other materials, where tiling is continuous across junction's of other background materials, in large tiled areas at internal vertical corners and as intermediate joints, and where stresses are likely to be concentrated.
Once you've specified your tiling project it's essential that the tiling work is undertaken correctly. Let's take a look at best practice regarding adhesive application techniques. The size of notch trowel chosen depends on the surface being tiled the profile on the back of the tile and the degree of coverage required.
For tiling wall in dry internal conditions the adhesive contact should be a minimum of 50% of the back of the tile, ideally 75%. However when tiling to flaws all external locations and wet areas such as showers and swimming pools solid bed fixing should be achieved with 100% coverage to the back of the tile. It's advisable to lift a tile now and again to check solid bed fixing is achieved.
Ensure that the adhesive has been applied in ribs and the back of the tile buttered with a thin layer of adhesive before it's firmly pressed in place with a twisting and sliding action within the open time of the adhesive, prior to a skin forming. This method of fixing allows full contact of the adhesive with the back of the tile and substrate. One method of achieving solid bed fixing is to butter the back of the tile for floor tiling but with pourable adhesives this is not necessary.
In the last decade there has been a trend to larger format tiles in order to achieve a solid thick bed under these tiles pourable adhesives have been innovated to help succeed in solid bed fixing without the need to butter the back of the tile. Particularly when rapid drying these can effectively speed the installation time.
Here we see an example of how solid bed fixing can be achieved by using modern pourable floor tile adhesives. We would never condone blob fixing of tiles it often leads to cracking and delamination as the tiles are subject to a lack of support and differential stresses. A lack of solid bed fixing can leave the installation prone to impact damage in the future or cracking tiles.
Having researched and produced the specification and contractor’s guidance, once the project is underway:
- Site visits monitor best practice to ensure that your specification is followed.
- Future trip hazards, cracked tiles etcetera are avoided.
- Movement joints are incorporated.
- The background is as specified.
- The tiles are as specified.
- The adhesive installation is tiled with solid bed fixing using the advised trowels and specified products.
- The grout joins her as specified and adequately filled with the specified products and well cleaned off.
- The contractor is aware of Coshh health and safety on site.
- A cleaning and maintenance regime is observed especially when specifying natural stone or wear slip resistance is essential.
We have reviewed the three main considerations when specifying tiling and the effect that each has on adhesive and grout selection. We have looked at the pivotal role that the adhesive plays in the overall success of the installation. We have reviewed products like microtec, which are considerably advanced on the standards and provide exceptional real life performance on site. These products were designed for tomorrow but used on many sites today and outperform the standards. Clever products, easy to use and guaranteed to perform.
With microtec you can specify with confidence. They have been used on many prestigious projects and many difficult installations to date. Tiles can create a perfect finish for most environments.