>Tiling Questions and Answers

Tiling Questions and Answers

Why use adhesive

To lay tiles with sand-cement traditional way is to apply the mixture of sand-cement in lump on tiles’ back so it has to be done with one tile at a time.

Without additive to help retaining water, mixture of sand-cement dries fast and then causes the difficulty to adjust the tiles after being laid. This leads to aesthetic problem of the line of tiles and also poor bonding strength, which will be the reason of de-bonded tiles later.

Laying  tiles  traditional  way  by  applying  sand- cement mixture in lump at tiles’ back will create voids underneath the tiles and water can seep through. This creates white stain problem. Moreover, tile will be fragile at the area without any adhesive underneath

Thick layer of sand-cement mixture must be used to lay tile traditionally in lump and/or to adjust the floor level, in order to gain its bonding mechanism. There will then be more loads onto structure. Moreover, there will be material wastage since the mixture dries faster than the application.

So what are the benefits for using tile adhesive to lay tiles?

  • Tile adhesive is very easy to use, it will be already ready to use after just mixing with water. Bagging product makes it convenient for transportation process, providing low dust and clean working space.
  • Tiles are not needed to be soaked, just un-box them and lay.
  • Optimum setting time of tile adhesive allows tiles to  be  easily  adjusted  within  a  certain  period  of time. It makes tiles being laid in line and gives the aesthetic final look.
  • Applying tile adhesive with notched trowel provides full spread on back of tiles and will reduce many problems like broken tiles on the corner, water seeping, and stain or efflorescent.
  • Full contact of the adhesive on tiles’ back and substrate provides strong bonding strength and long lasting tiling work.
  • Tile adhesives are formulated according to specific applications such as to lay tiles, glass mosaics, large-size granite (up from 60 x 60 cm), to lay tiles on polished substrates, on dry wall system, on existing tiles without removing them, on external areas, parking areas, industrial areas, in swimming pools, and many more.
  • Laying tiles by using tile adhesive with notched trowel requires less amount of material. Adhesive layer is a lot thinner than the mixture of sand- cement, and this leads to lighter load to building structure. A bag of 20 kg tile adhesive can be used to lay tiles on the average area of 4 – 5 m2
Loose Drummy Tiles

If your floor tiles are drummy or hollow sounding, you really do need to take some action. This situation will generally become obvious as soon as the tiles are laid.

It means that the adhesive does not have a good bond between the tiles and the substrate, or that there are hollow voids of missing adhesive under the tiles. If tiles are laid correctly and there is 100% adhesive coverage, and the bond is sound, then the tiles effectively become one with the substrate.

As the floor is used and subjected to foot traffic, the tiles that are not correctly laid will most likely break, crack, chip, or fail in some other way. In extreme circumstances, the tiles will actually lift off the floor.

What can cause the problem?

Drummy or loose tiles can be caused by a number of reasons including:

  • Not enough adhesive under the tiles, or ‘dobbing’ of the adhesive under the tiles. This leaves hollow voids.
  • The wrong adhesive has been used and it has not bonded with the tiles or substrate. Or, in wet areas, the adhesive is not suitable and has broken down.
  • The  adhesive  has  skinned  before  the  tiles  were laid. This means that the adhesive was put down and left too long and the surface has dried. This prevents a sound bond to the tile.
  • If the suspect tiling is over a timber floor, then the incorrect adhesive may have been used. Special adhesive must be used for a permanent and sound bond over timber, and the instructions followed closely.
  • Excess  movement  of  the  floor  boards  can  also create a problem, especially if the adhesive is not a ‘flexible’ product.

So what is the solution?

The bad news is that any drummy or loose tiles on a floor will cause problems down the track. This situation is not a fault of the tiles; the builder, tiler or tile retailer must take responsibility.

If the retailer specified the wrong adhesive, then that needs to be corrected. The first step is to talk to the retailer and check the suitability of the adhesive.

If the tiler has supplied the adhesive and it is not suitable, or he has let it skin, or he has not prepared the floor correctly; then he will need to correct the problem.

Likewise, if there is excessive ‘bounce’ in the timber floor, then  the  builder  or  tiler  needs  to  rectify  the  project. The excessive floor movement should have been fixed before the tiles were laid.

Loose Drummy Tiles

Structural movement in homes and buildings is a fact of life. Different substrates will move, settle, shrink, or expand depending on the conditions. Some tiles can also grow in size as they absorb moisture in the period shortly after manufacture.

Problems can develop if tiles are laid without flexible adhesives, and no allowance for the expansion and contraction of the substrate.

One situation that can develop is if tiles are laid onto concrete before it has had time to completely cure. The general rule of thumb is to allow one month to cure per 25mm of thickness of the concrete slab. Even then, the average house slab can take up to two years to completely cure (and shrink). If this Structural movement is not allowed for by using the correct adhesives and including expansion joints, something has to give. There have even been reports of tiles exploding unexpectedly. This is due to extreme lateral pressures as the walls and floor move in different directions. Nobody is expecting their tiles to explode!

What can cause the problem?

  • Not using the correct adhesive over a concrete slab that is still curing (we refer to such a slab as being green).
  • Not allowing for expansion or movement around the perimeter of a tiled area, and at 4.5 metre intervals in a grid pattern through the floor.
  • Incorrect  installation  of  movement  joints.  These must travel through the tile and adhesive to the substrate and must by fully filled with a flexible silicone or rubber compound.

Incorrectly laid tiles are solely the responsibility of the tiler or builder. You will need to arrange for the tiler or builder to fix the problem.

In the unlikely situation that the problem is discovered early, and a flexible adhesive was used, and some tiles have not actually exploded, one solution can be to cut expansion joints around the perimeter. This is done by cutting 6mm off the edge of the tiles (through both the tile and the adhesive bed) and removing that strip. Then fill it with silicone. This is not a guaranteed solution, so it may still be worth talking to your tiler or builder.

So what can I do now?

The only remedy is to remove the tiles and retile the area correctly. The movement that would cause buckling prevents replacement of the buckled area, because the removed tiles will not fit into the smaller space.

Why does grout change colour to white

Under   certain   circumstances,  a  white  powder  can form on grout, especially on floor tiles. This is a natural phenomenon called efflorescence. It is due to soluble salts rising to the surface of a cement based product. When they dry out on the surface, the remaining salts appear white and powdery.

Efflorescence  often   manifests   itself   in   the   cement joints of new brickwork. Numerous studies have been made around the world to try to determine why it can appear on one installation, and not on another under apparently identical conditions. One of the few things we do know are that it happens when Portland Cement is present, and that there is no real solution for it. Efflorescence does clear up over time unless there is an ongoing issue with rising damp from the substrate. It is defined as the ‘migration of soluble salts.’

This is not due to substandard tiles, adhesives, or grout; and generally, there is nothing to worry about.

What can cause the problem?

As explained, is it simply soluble salts that are present in the cement based product. This can be the concrete, mortar bed, tile adhesive, or grout. These rise to the the surface, and as it dries an annoying white powder remains on the surface. The grout is the weakest link in the floor surface, so this is where the salts will migrate.

So what can I do now?

The only real solution is to brush the grout with a stiff bristled brush and vacuum away. Repeat this from time to time, and eventually, it will generally stop recurring. You can also wash the area with a 50/50 mix of water and Phosphoric acid. Apply, leave for two minutes and then rinse thoroughly.

Some people advocate brushing the salts away and then applying a grout sealer. While these are great products and are worth using in many situations to keep your grout clean and seal out dirt, these products won’t always stop efflorescence.

Why does grout go crumbly and soft

Grout is used to fill the joints between tiles and help make a smooth, attractive surface that is both water resistant and easy to maintain. If the grout is crumbly, or powdery and falling out; it is obvious that it can’t perform this task.

It is important to remedy this situation quickly, especially in bathrooms where this risk of water penetrating the joints and causing damage to the substrate or the building structure.

Crumbly or powdery grout is due to poor mixing and application.

What can cause the problem?

When grout and water are mixed together, a chemical reaction called ‘hydration’ is started. It is this reaction that causes the grout to go from a thick paste to a hard tile joint. Powdery or crumbly grout is likely to occur if the tiler:

  • Doesn’t wet the joints before applying the grout.
  • Doesn’t mix the grout to a consistent, thick and creamy paste.
  • Doesn’t fill the whole grout joint and compress the grout into the joint when grouting.
  • Uses old grout that is past its expiry date or shelf life.
  • Before application, and especially on soft biscuit wall tiles, the tiler needs to wet the joints where he intends to grout. This extra moisture slows the hydration process. With soft biscuit tiles, the body of the tile soaks up the moisture in the grout. With incorrect hydration, the grout will not cure or dry correctly and the result is powdery or crumbly grout.
  • If  the  grout  is  not  mixed  thoroughly,  patches  of grouted areas on the wall or floor will end up powdery or crumbly. The use of a rubber squeegee (trowel) and a firm sweeping action across the joints ensures that the grout is compressed into the joint and completely fills the joint without voids. Incorrectly applied grout will be unserviceable and is likely to crack and fall out over time.
  • Grout  has  a  shelf  life  of  about  12  months  from date of manufacture. After this time it is likely to go powdery and is unsuitable for use.

So what can I do now?

The only way to rectify this problem is to scrape out the grout and replace it. This is done by using a grout rake (a small, cheap tool available at all Beaumont Tiles stores). Once the joints are clean, apply the correctly mixed grout.

Note: Never grout the internal corners between two walls  or  the  internal  corner  where  a  wall  and  floor meet. Movement and different rates of expansion and contraction will cause these joints to crack and fail. Silicone must be used in these places.

Why does grout go dark or black

If your grouting has gone dark or black, it is just dirty. This does not mean that you don’t keep a clean home or floor, but simply that the way you have been cleaning is not best suited to tiles.

The most common cause of this is that people wash their floors using too much water and detergent. The dirt is washed off the tiles and collects in the grout joints. It settles in these mini gutters and dries out leaving a film of dirt and detergent. Each time the floor is washed, this film builds up and eventually causes the grout to appear black. In truth, the black is just the film of grime sitting on top of the grout.

In some areas where there is ongoing dampness, such as a bathroom, this film is an ideal breeding ground for mould.

What can cause the problem?

Cleaning the floor with too much water and detergent and then not rinsing thoroughly is the most common cause. We should explain here that the way detergent works is to capture dirt and grease on the microscopic level. The reason we mix it with water is to enable this mini globules to be washed away. If we leave a floor wet without rinsing, that film will stay on the floor, especially in the grout joints.

Whenever you wash a floor using any form of detergent, rinse it well with clean water. Most soiling on glazed ceramic tiles will lift off with plain, clean, warm water. The only thing we recommend that you add to the water is a drop or two of disinfectant (or a splash of vinegar) to kill any germs. Any greasy or oily marks can be cleaned up as a spill. For overall cleaning, leave the detergent in the cupboard.

So what can I do now?

Visit your tile store and purchase a bottle of Tile and Grout Cleaner. View DuraPro tile cleaning products. Use them to wash the floor (and rinse several times) to remove all the built up grime.

From that time on, avoid detergents and just use warm water. Always use the water sparingly; there is no need to flood the floor.

Once the floor is thoroughly clean and dry, it might be wise to seal the grout joints with a grout sealer. Once light application using the trigger spray will seal the grout joints and make them water repellent and easy to clean for around five years.