Floor tile installation problems and solutions

As in most things, knowledge is key and laying floor tile is no exception. Today we'll look at some potential problems that can occur from incorrect floor tile installations and what you can do to avoid them.

Concrete slabs

Many tile installations are laid directly onto concrete slabs by adding a layer of thinset and applying the tile directly. However the potential problem here lies in the two items, the concrete slab and the tile. Concrete, like everything, expands and contracts and it does so at a different rate than the tile that is adhered to it. Naturally when two attached items move at different rates, something has to give and in this case it's usually the tile. Wooden sub floors will also move at different rates. The resulting movement to the tile is called "tenting" and much as the name implies the tile looks like a little tent when forced together.

Tenting

"Tenting in a tile floor"

The solution is to add a layer between the subfloor and the tile that uncouples the floor whether that floor is concrete or wood. Using a cement board from various manufacturers or a product from Schluter called "Ditra."

Cement backer board

Illustration of Ditra installation

Both products will effectively keep the subfloor and tile moving around at their own rates, leaving all parties content and in place.

Below is a great video showing the installation of floor tile and Ditra done properly. This is for a wood substrate but Ditra is also a great product to use on concrete slabs too.

Tenting can also happen because the tile was grouted right to the baseboard versus leaving that last wall to joint empty (no grout there) and applying the baseboard above the tile. This leaves a place for expansion. Another area of potential concern are kitchen and bath cabinets so make sure that you allow for expansion areas along those edges too.

Plants

Oddly you may not even consider this one but plants that are large and in heavy pots can cause tenting. Due to the large size of the plant, pot and soil and if they are occupying a few tiles on the floor, those tiles are not being allowed to move at the same rate as their neighboring tiles and the result may be a large cracking noise some evening as the tile moves or rather the other tiles move.

Expansion joints in large areas

You may also want to consider or confer with your installer about installing an expansion joint and again this one is made by Schluter. Generally a distance of 25'-30' is the most that an area should be tiled without adding an expansion joint such as shown below.

Expansion joint

Another area that re-modelers often face is when two different substrates are to receive a new tile floor. For example part of the area to be tiled is concrete and part is wood. Here we have two different movements to contend with as they both contract and expand at totally different rates. Adding a layer of cement board or Ditra will uncouple the two from the tile and allow them to move at their own rates without effecting the tile above.

Thinset and grout

This one is easy. Just remember that all thinset and grout are made with Portland cement and are dry bagged products. If you are doing the installation yourself and see a premixed thinset or grout on your store shelf and think you'll be saving time and effort, you probably won't be. The product you are viewing is not what you generally will be needing. My advice if you are trying to do a tile installation for the first time, make sure you read and learn all that you can to avoid problems down the road. If you are not 100% sure? My advice would be to hire a professional installer as it will be money well spent over the lifetime of your tiled floor and avoidance of future problems.

Why grout cracks in tile installations

The most visible part of any tile installation is, of course, the tile but what is the next thing you see. The grout! The grout, in many ways, is more visible as the smaller lines that make that up can draw your attention away from the tile itself. If those grout lines have cracks or are crumbling, your eye will naturally shoot right to it.

So let's look at few things and how they should be handled to make sure that the grout you use compliments your beautiful tile. Do you know the difference between sanded and unsanded grout and where each should be used? Now the difference in the two is easy. One has sand, one doesn't.

Applying grout

Now where to use which one is determined, not by the tile itself, but rather by the width of the joint between them. 

"Narrow joints of 1/8 inch or less call for unsanded grout, a pudding-smooth blend of Portland cement and powdered pigments mixed with water. Joints wider than 1/8 inch get sanded grout — the same material, but with sand added. The sand helps bulk up the grout and keeps it from shrinking in the joints." - ThisOldhouse.com

Now why does grout crack? You've applied the proper grout but down the road cracks start to appear in your grout lines and there can be many reasons but most have to do with the installation long before the grout was added. Most of what we will look at today is in reference to flooring but there are many points that are similar with all tile installations.

1. The first potential reason is that the thinset below the tile was improperly applied and does not have enough thinset.

Applying thinset properly

2. The subfloor is moving and as it moves the grout lines crack.  Did you apply the tile directly to the wooden subfloor? Tile should never be applied to a wooden subfloor due to the natural movement that is part of wood.

3. Was the cementious backer board that was applied over the subfloor installed correctly? Maybe there weren't enough screws or thinset below or it was spaced improperly. Any of these could cause movement and that causes cracks.

Proper spacing of backer board

4. As another possibility- Is there adequate space between your wall or wooden trim and your grout? Grout doesn't contract and expand but wood does and that could be part of the issue too. It is a good idea to leave a 1/4" space between any tile and wooden baseboards or trim so that if the wood expands, it will not apply pressure to the tile and possible crack the grout. To accomplish this a "shoe" molding can be applied to the baseboard, effectively covering the gap and allowing the baseboard to move above the tile while applying no force to the tile or grout.

5. Did you apply your tile on a newly finished/poured concrete slab? Concrete has to cure and as it does it moves, so if your concrete floor or base is new and the tile was applied too soon, it could be the reason your grout is cracking. 

Cracks may develop and also crack the tile

I would also add there could be other reasons for grout to crack other than those listed above such as improper mixing  ie too much water in the mix. This would cause the grout to improperly dry leaving it prone to cracking later.  It could also be that water was added again later in the mixing process and this will cause the grout to be dry and crumbly.

Now if you are still in the planning stage I would offer a suggestion or rather a product and installation method that will help avoid the problem of movement and grout cracks. It's a mat that is laid in a bed of thinset and then a layer of thinset is applied above with the tile and grout.

Schluter-DITRA-X

What this mat does is provide a separation between the sub flooring material, whether that be wood or concrete so that if there is movement in the concrete/wooden sub floor, it will not translate up into the tile and grout and cause cracking.The mat will take the added stress of the movement below and not the tile/ grout therefore helping to eliminate cracking. For further reading about this product-http://www.schluter.com/Schluter-DITRA-XL.aspx 


As we have pointed out before, planning ahead and armed with knowledge will lead to a successful installation as it is so much easier to do right the first time than have to go back and correct later.