Wall Tile Adhesive- Choice
Choosing a tile adhesive for your walls in usually quite straight forward, traditionally you would go to your supplier od DIY chain and pick up a bucket of ready mixed wall tile adhesive which is usually available in a 15kg bucket and is ready to be applied to the wall, but there are some important points to consider before you make your adhesive selection:
- What material are my tiles manufactured from?
- How fast do I need to complete the tiling?
- Do I require a specific colour of adhesive?
- Do I need to buy a water-resistant tile adhesive?
- Is my substrate a stud type wall and in need of flexible adhesive?
A ready mixed wall tile adhesive that typically is available in a bucket as shown (10 litre or 15kg) has some limitations in its use, especially now that we are wanting to use many different tile types in our bathrooms. A ready mixed wall tile adhesive should only be used with a porous type tile such as ceramic and with tiles that are relatively small in dimension by todays standards, such as tiles under 300mm x 300mm. The reason for this is that ready mixed adhesives cure by way of the water dispersing into air and therefore requires a porous surface or tile to dry into and it will dry from the grout joints with air transporting from the edge of the tile to the centre (over time) If the tile is a large format size then the adhesive in the centre of the tile will struggle to dry, or it will take an extremely long time. This is the reason that it is very important to not grout the tiles until the adhesive is dry, as by grouting the tiles you are creating another barrier which will inhibit the drying of the adhesive. This is a similar reason as to why you should not really consider a ready mixed wall tile adhesive to fix glass tiles or porcelain tiles, these tiles have none or virtually no porosity in their body and the adhesive will struggle to dry and create a strong bond with the substrate. If you are going to use a ready mixed wall tile adhesive with glass or porcelain then please make sure that the tiles are very small which then will give the adhesive a chance to dry out through the grout joints (under 100mm x 100mm is a good guide)
The same can be said if you are tiling onto a substrate which is waterproof such as a tanking system or a waterproof cement backer board, the ready mixed wall tile adhesive will take much longer to cure as it cannot dry into the substrate as it would with something like plaster or plasterboard, so instead of a 24 hour cure , you may be looking at 72 hours or more. You can use a ready mixed wall tile adhesive to tile onto existing tiles, but again leave the adhesive enough time to dry before grouting as the existing tiles will slow down the drying process.
If you are choosing a ready mixed wall tile adhesive for your bathroom, then you should really choose a water-resistant type which in the UK will have a stamp on it somewhere that will say (D2) or Class AA. Do not be mislead by the descriptions on the buckets as you can easily make the wrong choice. There are adhesives that may have “showerproof” in their title or “suitable for domestic showers” in their description, but if you examine a little more then you will notice that a feww of these products will be type (D1) which means not water-resistant and therefore possible to dissolve in water over time. The reason that these products can be described as suitable for domestic showers is that with a domestic shower, it is expected that it may get used once or twice inh the morning and then will have all day to dry out during the day before being used again in the evening. This type of use is unlikely to cause any problem and break down the adhesive causing failure, but would you really want to take the chance? I am sure you sert out to use a water-resistant product in a shower, if just for peace of mind and we are using higher power showers these days which will be transferring more water through the adhesive. You can easily tell the difference between a water-resistant and non water-resistant adhesive as you are using them, when you go to clean off your tools, trowel etc the water-resistant adhesive will be much more difficult to clean than the non water-resistant. Also do not expect to find a truly “waterproof” tile adhesive, even if the packaging tells you otherwise, there is no such product as they all contain water, this is a scientific impossibility to have a waterproof product that contains water. Water resistant means in basic terms that water will pass through the material but will not affect its properties or degrade it in any way, do not fall into the trap of believing tiles and grout will protect your substrate from water.
The positive aspects of ready mixed wall tile adhesive are that it is ready to go from the bucket with no other preparation needed, it also can be used onto gypsum based substrates directly with no priming required. Gypsum (otherwise known as plaster products) are most popular in the UK as opposed to other countries. Plaster will be the substrate in 80-90% of bathrooms in the UK and is not actually an ideal substrate to tile onto. The reasons plaster is not great as a tiling substrate is firstly that it is not water-resistant, so if enough water comes into contact with it, then it could eventually fail. If you do not want to take the risks then you can overcome the water sensitivity issue by tanking the plaster with a suitable system, which will protect the plaster or plasterboard from water ingress for the life of the tiling. Plaster also has a low weight limit of 20kg per metre square which includes adhesive and grout, as tiles are becoming thicker and heavier this can become an issue. plasterboard is less of an issue with weight as it is possible to hold 32kg per metre square onto plasterboard. Plaster will also need to be dry before you consider tiling onto it, this is recommended to be 4 weeks from the plaster being applied. A major mistake often made by building companies and individuals is that they plaster skim plasterboard substrates prior to tiling which is a total waste of time and money and an exercise in actually degrading the installation. If you have a plasterboard substrate, then tile it directly as it holds more weight and has no drying time.
Choose a flexible wall tile adhesive if you are tiling onto a stud type wall such as plasterboard or cement backer boards, these flexible adhesive allow for small amounts of expansion, contraction and vibration through the walls and also give you a stronger bond with the substrate, but do not tile onto any substrate which is physically moving or deflecting too much as flexible tile adhesive cannot overcome these issues mainly because tiles are a rigid finish and cannot take any movement at all so will either de-bond from the substrate or crack depending on the weakest point at the time of the excessive movement, every substrate should be clean, dry, stable and flat.
Wall Tile Adhesive- Alternatives
If you would like an alternative to ready mixed wall tile adhesive then you can go for the safer option of cement based adhesive which covers many more bases than the ready mixed wall tile adhesive. Firstly make sure that the cement based adhesive you’re considering has the words “non slip” somewhere, as this basically means that it is suitable for wall tiling, as some cement based adhesives are designed only for floor tiling where non slip is not required and if used on a wall will provide a rather frustrating experience for the tiler as the tiles start sliding down the walls
Cement based adhesive has the added benefit of being a hydraulic cure, which means that it will dry regardless of the type of tile or where it is used. If you mix a cement based adhesive in a bucket and then put the lid on top, it will still dry in the specified time, unlike ready mixed adhesive. This gives us more control over the job when using low porosity tiles or waterproof substrates such as tanking as we will not have to wait extra time for the adhesive to dry. There are two setting speeds of cement based adhesive, standard which is usually 24 hours and rapidset which is typically 3 hours. You will find that rapidset adhesives are mostly used by professionals as when mixed with water in the bucket, the pot life of such products is only about 30 minutes before the adhesive becomes un-useable, so if you are not fast, you could end up throwing lot’s of expensive product away. Rapidset adhesive is also mostly used on floors because of the need to be able to walk on a floor, but this is not essential and only if for example you have only one toilet that you cannot be without for 24 hours. Standard setting products have a much more forgiving pot life or approx 4-5 hours once mixed in the bucket and therefore can also be used by the DIY tiler. Mostly the standard set will be used on walls as walls tend to have more cutting to deal with and takes a little more time, plus the need to dry fast is not a pre-requisite.
If you are wall tiling then you will probably need a white adhesive (especially if grouting with a light coloured grout) or if you are tiling a natural stone or a glass tile. Light coloured natural stone is translucent and if a dark coloured adhesive is used, you can have dark shadows appear through the tiles which will not disappear, when in doubt use white. Make sure that you achive a good coverage of adhesive behind the tile, especially in shower areas and especially when using glass or translucent tiles, this gives you a good contact with the substrate and also should there be any transparency, you will not be able to see the shadows behind the tiles. The choice of trowel and size of the tile will denote the coverage achievable, if you’re not confident in achieving this, it is always better to get in the professionals.
Wall Tile adhesive- Priming
If you are using a cement based tile adhesive and the substrate is either plaster or plasterboard, then you will need to prime the surface first as there can be a chemical reaction between cement and plaster when used directly onto each other. Please do not use PVA type primers to prime the surface as this should not be used in any capacity with tiling, it is water sensitive and dries like a skin onto the surface of the plaster, which basically means you are sticking your tiles to a thin skin, this is a potential failure. If you need to prime, then purchase a proper SBR type primer which is designed to be used in tiling applications and is water-resistant and strengthens the bond of the adhesives to the substrate, it has many uses as a primer for tiling. read the manufactures instructions on the packaging for information in regards to dilution and use as this does vary slightly depending on what tiling situation.
The only wood you should consider tiling onto is marine grade plywood, this is because it is a good quality wood but it will still require tanking in a wet area and secure fixing to a baton framework behind. The picture here shows a sterling type board being prepared for tiling, this type of wood is not suitable for tiling full stop, even primer cannot make a difference here and it is a significant risk to tile onto such boards.
Wall Tile Adhesive- Conclusion
There is still a place in the market for the ready mixed wall tile adhesive type, this will be when fixing small ceramic tiles to large areas such as contracts or in the home when you are tiling a kitchen or toilet with ceramic type tiles, it is convenient to use with no need for priming in most instances. But, this product is starting to become less and less used as the tiles we use changes and our expectations as to where we want to tile are evolving. A Tiler who wants to cover all eventualities without keeping every type of adhesive on his van will have only cement based adhesive, as he knows he can use this iv virtually any situation and he has more control over its consistency. The most important factor is that if you are going to use cement based adhesive, it is very,very important that you prime gypsum substrates first. As you can see, there are some serious considerations to make when choosing your tiles and ancillaries, people tend to ignore the importance of adhesive in favour of investing heavily in their tiles, but do this at your peril as the cheapest option can often lead to failure. Use some of the information contained on this page to make an informed decision on which wall tile adhesive to choose and you can rest easy.
If you have any questions or comments in regards to wall tile adhesive, then please post in the comment section below.