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How to apply mortar to floor

You’re finally ready to get your hands – or at least your trowel – dirty and lay your tiles. After consulting its label, carefully mix your mortar.

Quick Tip

You're "combing" the mortar right if you hear a grainy scrape. If you can see pinholes in the mortar, then you're not applying the mortar properly.

A graphic highlighting the 6 steps showing how to lay floor tile with mortar.

1. Use the flat edge of your trowel to apply mortar.

An image of a person using the flat edge of a trowel to apply tile floor mortar.Install your floor according to the quarters you drew in chalk while laying out your tile design. So, plan to begin at the center point of the surface and move outward – covering one quarter at a time.

Begin in the farthest quarter from the exit and work toward it, to avoid walking all over freshly laid tile. When this is unavoidable, put a plywood sheet over freshly laid tile and kneel on it while installing. Make sure there is no adhesive between your plywood and the tile – otherwise, you’ll pull up tile when you move the board. With the flat edge of the trowel, apply thin-set mortar, beginning at the intersection of the guidelines and working outward.


2. "Comb" the mortar

An image of a person combing tile floor mortar to form even ridges.

Then, using the notched section of the trowel, go back and “comb” the floor mortar to form straight, even ridges. Don’t be afraid to apply pressure to your trowel! 

Work in areas of about 3 square feet at a time. If your adhesive loses its tackiness to the touch before you lay tiles, you’ll need to stop setting, scrape the floor clean and re-apply mortar.




3. Bond the Tile

Two hands laying down tile, bonding it to the tile floor mortar.

If you carefully laid out your tile before mortaring, bonding the tile to the 3-square-foot sections you’ve mortared should be relatively simple.

Press your first tile firmly into position at the intersection of the lines, with a slight twisting motion. Do not slide the tile into place.



4. Use tile spacers
A diagram to show how to adjust tile spacing when doing a floor tile installation.If your tiles are not self-spacing, place spacers between them to maintain even grout joints. You can buy tile spacers at Lowe's.






5. Work upward and outward

Two sets of hands doing a floor tile installation in an upward and outward direction.Install tiles in a step-like pattern, working upward and outward. That is, the first row of tile placed in the mortared area should have the largest number of tiles, and each row after that should have one or two fewer tiles. Installing in this pattern allows for easier adjustment of tiles if there is an error. 

No matter how “in the zone” you get, periodically take a step back from your floor to make sure that your joint lines are straight and even.



6. Tap down tiles 

A person using a blue mallet to tap down the floor tile to ensure they are level.

If you're happy with your floor's appearance, tap down tiles with a beating block and mallet to ensure that they are level. Make sure to use a beating block – otherwise, you might crack your tile. If adhesive oozes from the joints, wipe them with warm, soapy water. At least 2/3 of the tile thickness in the grout joints should be completely clean to allow for grout. 

Complete one quarter of the floor before going on to the next – remembering to leave room for movement joints between the tile and adjacent walls. 


Wait Time 

Patiently follow instructions on the mortar regarding its wait time. If you’re setting tile in an especially cold or humid environment or over existing tile or laminate, allow more time for the tile to set before grouting. Similarly, larger porcelain and glass tiles also have extended set times.

After the floor mortar has been laid and the floor tiles are installed, the next step on the path to a great floor tile installation is to grout the floor.

Our diy Expert

Ron Sheldon

Ron Sheldon is a tile and floor installation guru. He has far too much knowledge on obscure topics like grout and floor leveling. A passionate tile contractor by trade, Ron’s spent the past decade dedicated to educating people about tiling, and has great advice on how to perfect your project.

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