How to Lay Tile Over Concrete

Lead Image
What You'll Need
TSP (tri-sodium phosphate solution)
Concrete Patch/floor leveler
Concrete Sealer
Chalk line
Grout Float

Ordinary concrete is fine for your average backyard patio, but to create a rich, inviting outdoor patio space, installing tile is the best way to go. There is a huge selection of tile styles and colors for you to choose from, and the greatest benefit of using tiles is that they can be laid directly on top of preexisting concrete.

Once you've gone through all your options and found a tile style that suits you, these instructions will help you plan out your project and install the pieces without overlooking important details.

Laying floor tile over concrete is not a technically demanding job. It can be physically strenuous and messy, but it is a home improvement project that will allow you to cut labor costs by doing it yourself.

Step 1 - Preparing the Concrete

Before you begin to lay the tile over your concrete slab, make sure the concrete is properly prepared. Mix up a bucket of TSP (tri-sodium phosphate) solution. TSP is a high-strength cleaner, which is useful for removing dirt, grease, and oil from your existing surface. Scrub the floor with a brush and TSP, and allow it to dry thoroughly. Then examine the floor and see if there are any cracks or pits that need to be fixed before you lay the tile.

Keep in mind, any uneven areas will allow the tile to rock back and forth, even after installation. If the tile isn't completely flat, it will probably crack somewhere down the road. Take the time now to use the concrete patch or leveler to ensure you have a flat surface with no defects.

Step 2 - Seal the Concrete

Once your repairs have dried, seal the concrete. True, using a sealant is an extra step in the process, and you don't really need to do it, but in the long run, it will be time well spent. Applying a sealant will prevent moisture from settling under your tiles and will allow your mortar to stick tightly.

Step 3 - Plan Your Layout in Advance

As you get ready to begin laying the tile, you will need to decide ahead of time where you want your configuration to begin and end. This is important because you will most likely have to cut pieces at the end to make them fit. It is usually best if these cut pieces are in inconspicuous places, such as against the home. Plan your starting point accordingly to ensure that you can hide the cut pieces as well as possible. It is best to mark your starting point on the concrete floor and snap a chalk line the entire length of the room. You can use this line as a reference point to make sure that your first row is square and even.

Step 4 - Mixing Mortar

After you have decided where you want to begin, you must mix and put down a layer of mortar. Keep in mind that different varieties of mortar work best with different types of tiling so you should make sure your selections are compatible. Once you've chosen a mortar, follow the instructions provided by the manufacturer and begin to mix the mortar. Don't mix too far in advance, as it will begin to set on you before you can use it.

Step 5 - Applying Mortar

Begin spreading the mortar over a small area using a trowel. As a tip, a grooved trowel will work the best for this kind of a job.

Never spread out more than what you can cover with three or four tiles at a time. If you run into trouble and have to stop or slow down but you've got a huge area of mortar already spread, it may start to set up before you can get the tile down. Just do a little at a time, and you will save yourself a potentially huge headache.

Step 6 - Installing the Tiles

Lay the tiles into the mortar, and using the spacers, make sure you are running even with the chalk line. As you move on to the subsequent rows, use the spacers to keep your pattern square. Once a tile is set, try to avoid touching it again. As soon as you make a small adjustment to one, you will find that you need to adjust them all. It is far more efficient to get it right the first time and not have to touch it again.

Wash the tiles off with a damp rag as you go. If you leave clumps of mortar to dry on the surface of the tile, it will make cleaning them later much more difficult. As you get to the end of the room, make sure your cut pieces fit properly, and then leave the mortar to dry as specified by the manufacturer's instructions.

Step 7 - Grouting the Tile

The next step is to grout the tile. Mix the grout as specified on the package, and begin liberally spreading it over the tile using the grout float. Use the float to make sure there are no low spots. Then use a damp rag to wipe any excess grout from the face of the tile. Once the grout has had time to set, repeat the process. Don't worry at this point if the tile appears a little cloudy.

Step 8 - Cleaning Up

Once the grout is completely dry, take a wet rag and wash the surface of the entire floor. As the floor dries, you will probably notice a haze forming over the tile. Allow it to dry completely, and then go back over it with a slightly damp rag. This should polish the haze right off.

Once you have polished the remaining grout and mortar residue off of the floor and are confident that the grout has fully cured, use the grout sealer to prevent stains and mildew from taking hold in the future.

Brian Simkins is a freelance writer living in Chicago. He enjoys using his 14 years of home improvement experience to educate and equip new home owners.