9 Tips for Perfectly Laying Tile Over Concrete

Kristin Luna
Written by Kristin Luna
Updated April 27, 2022
A mother and her daughter putting shoes on the kitchen tile floor
Photo: Chad Springer / Image Source / Getty Images

Install a showstopping floor with these tiling tricks

Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.

The prospect of a new tile floor is all kinds of exciting. It lets you alter your environment while leaning into your specific aesthetic. But if you’re new to DIY tile installation, there are a few tips you’ll want to follow to make the process of laying tile over concrete as painless as possible.

1. Get the Underlying Surface as Level as Possible

Before you begin tile installation, it’s important to address the underlying concrete slab. If you’re dealing with an old floor that is chock full of cracks and patches, you’ll need to level it first. Tile will fracture along its underlying subfloor edges and seams, so it’s worthwhile to spend some time making sure that you remedy these situations before starting to lay tile over the concrete. 

If it isn’t possible to get your floor perfectly even from tip to tail, don’t worry: You can use thinset mortar to build up the lower areas to be even with the highest point in the room.

2. Smooth Your Subfloor as Much as You Can

A professional levelling a room’s subfloor
Photo: BanksPhotos / iStock / Getty Images Plus / Getty Images

Your flooring job is only as good as the surface beneath it. After you’ve made sure the concrete subfloor that will house your tile is as level as it can be, you’ll want to smooth it all out. A smooth concrete surface is the most ideal substrate for tile because you don’t need to waterproof it or worry about conflicting materials like wood. If the floor is especially rough, use a concrete grinder to polish the surface as much as you can, and if the substrate was previously a painted concrete floor, you’ll want to remove everything that is easily separated. 

3. Find Your Midway Line to Keep Tiles Even

Before you begin to install tile, you need to measure out your room and find the midpoint. Use a chalk line in 12-inch intervals to keep your edges and lines tight. This also will help you figure out the best layout so that there aren’t any awkwardly cut tiles at the end of the room. Before applying mortar to the concrete, it’s smart to lay out a row of tiles starting at the midpoint; that way, if either end results in a tiny sliver, you can adjust the midpoint slightly in either direction.

4. Avoid Tiling Over Cracks

If there’s a seam in your concrete floor as you prepare to lay your ceramic tile, avoid placing a tile over its line as your tile will eventually crack along that line. Instead, create your grout line to be harmonious with the seam or crack to ensure that when it does crack that it’ll be along a clean line instead of in the middle of a tile.

5. Be Sure to Spread the Thin Set Evenly

One way to wind up with hilly terrain for a floor is to spread mortar thick in one part and lightly in another. To avoid this from happening, strictly mix the product according to the manufacturer’s instructions and work the job in sections that you can handle. Using the proper notched trowel for the job is also important, so read the specs for your ceramic or porcelain tiles carefully.

6. Consider a Glue Mastic as an Adhesive

If you have a perfectly smooth floor, you don’t necessarily need to use a mortar-based mastic for the mortar bed as an adhesive to install ceramic tiles. Advances in materials technology have made it possible to use products other than the traditional cementitious mix that is thinset, and you should take advantage of this. Using a glue-based mastic has numerous benefits, including easier cleanup, less waste material, and the ability to carefully mete out the glue from a squeeze bag as you move along the floor.

7. Always Start Laying Tile From the Entrance

A worker laying tiles over concrete
Photo: alexandrumagurean / E+ / Getty Images

When you’re laying the tile over concrete, in addition to working from midpoint out, you’ll want to start with full tile pieces from the entrance of the room and work your way from front to back. That way, all those odd cuts that finalize the project are hidden against the least visible edge of the room. Again, once you’ve laid them all out prior to securing with mastic, you can adjust accordingly in either direction as needed. Lay large pieces of plywood over the top to enable walking over your finished work as you tile those harder-to-access areas.

8. Use a Level to Check Each Tile

Every time you’ve installed your tile spacers, use both a level and straight edge to ensure the tile is even with the previous piece. Getting into this rhythm will save you trouble down the line—the last thing you want is to realize the tiles aren’t even with each other after the mortar has already dried and the pieces aren’t as easy to maneuver.

9. Use a Grout Float on the Cracks, and Clean It Up

Once you’re ready to grout your masterpiece, be sure to use a grout float to squeeze the material into the lines. This will help clean up excess grout as you work, minimizing the amount of work needed to keep everything looking clean. You can even use your finger to trace each line and finalize the grouted areas. 

When everything has dried, you’ll need to go back over the tiles a couple times with a wet sponge to clean up the thin film of dried grout. Plan on making at least two passes before applying a grout sealer over the whole thing to prevent dirt and debris from building up as you start to use the room. 

If laying tile on a concrete slab isn’t your idea of a fun DIY project, you can always hire a local tile installer to tackle the job.

Need professional help with your project?
Get quotes from top-rated pros.