Want to know the top secrete tips for tiling over concrete ? This method will give you a strong installation that can last a lifetime. LITERALLY.
When it comes to a floor installation, the prep on the substrate (the surface you will be adhering the floor covering to) is THE MOST IMPORTANT PART OF THE INSTALL. Get this wrong and your installation will not last the test of time. In fact you can see a failure within days.
Materials such as laminate, wood, or vinyl are a bit more forgiving and don’t require as much in terms of preparation due to their flexibility. When it comes to any kind of tile, you have to be extra careful how you prep the surface before installing tile.
In this post we will cover the top secret tips for tiling over concrete.
Why you should use an underlayment for tile over concrete
An uncoupling membrane is very important as it helps prevent tiles from cracking when installing on top of concrete. Concrete naturally expands and contracts; by using the uncoupling underlayment, it mitigates this movement from cracking the tiles after installation. This is applied directly to the concrete with thin set.
Depending on your subfloor (The floor surface you are tiling to) you may need to take some precautionary steps before setting tile. Sometimes you will have a concrete subfloor or “slab on grade” like I will be demonstrating here OR you will have a wooden subfloor. A wooden subfloor can either be on the first floor of your home which would indicate your home is built on “pier and beam or block and beam” you may even have a crawl space. Sometimes the wooden subfloor is on the second story of the home. If you are trying to tile over a wooden subfloor, check out my Youtube Video Here.
Step 1: – Get rid of old thin set
The first step in tackling concrete prep is using a grinder to remove any old paint, debris, or material that may be stuck to the concrete. Here is an example of what the concrete may look like before beginning the grinding process.
After removing old flooring there will always be debris and old thin set stuck to the floor. You never want to lay tile underlayment or tile directly on a dirty and unprepped subfloor. Debris, old paint, and dust will cause poor adhesion for the thin set. This can lead to a failure in your tile installation down the road such as cracked for even loose tile.
We can prep the concrete using the 7’ floor grinder, the goal is to remove all of this material from the concrete so that it is clean. When you complete the grinding, the concrete floor should look clean and have a scuffed surface. This is similar to sanding furniture before painting. It creates a better prepped surface for thin set to adhere to.
Below is the floor after I removed all the debris. The floor is now ready for the next step.
After the grinding is complete and your concrete floor is free from debris, the next step in the process is to check for flatness. Before setting tile on a floor, you need to make sure its flat or level. Flat is when all parts of the floor are touching the bottom of the level.
** It is extremely important that you are using the proper sized level. For example, If you have a room that is 10 ft. in any direction do NOT use a 2ft level. This will not give you an accurate read of the floor and can result in poor preparation. I always like to check at least an 8ft span if my room is over 8ft.** You can get any size level here.
You may notice some high and low spots on the floor when you place a level on it. For the high spots, use a grinder to take those down. Any low spots you find may have to be filled in with a patching compound.
Once you have resolved any high or low spots on your concrete it is time to dry fit your underlayment. In this case we are using the Schluter Ditra uncoupling membrane. You can easily cut this with scissors or a pocket knife. I like to section off the room to get small working areas so that my thin set does not get dry.
Step 2: – Wet the concrete (Don’t skip)
Pro Tip: Be very careful when installing this. You want to make sure you work quick enough that the thin set doesn’t dry on you. If it is too dry you will not get the proper coverage between the substrate and the underlayment.
Concrete likes to absorb moisture, I recommended you wipe the concrete floor with a damp sponge to prevent the thin set from getting dry too quick. The quick wipe down will also remove any additional dust that may have settled on the floor. This also gives you some extra time to apply the membrane as the floor won’t pull out the moisture from the thin set as fast.
Pro Tip: Make sure to check the instructions from the manufacturer of your uncoupling membrane to see what thin set they recommend. Always double check for important installation instructions they may have. You can get a warranty if the proper installation materials are used.
Step 3: – Apply thin set
Apply your thin set along the subfloor in one direction. I used all Schluter products for this install which required a loose mix for the thin set. Make sure to double check the instructions for the product you use.
Step 4: Roll it out
After I have the thin set applied, I can lay down the underlayment (Schluter Ditra uncoupling membrane) and use a roller to collapse the ridges under and form a good bond.
As you use the roller to apply pressure, you will see the thin set will transfer to the back of the membrane forming the bond we are looking for. Repeat the same process for the rest of the sections of the floor. It is important to make sure you are collapsing the ridges behind the membrane to get full contact.
Here is what my floor looked like after laying down all the uncoupling membrane. Once the underlayment is all set, you are ready for tile!
This post is all about the 4 things you should do before tiling over concrete.
If you are planning on installing tile yourself, or looking to hire someone and want to make sure the job gets done right you can check out my video here going over this process.