How to Lay Slate Tile on Concrete

Slate is one of several forms of stone tile, along with marble, granite and travertine. Slate is known for its natural, slightly rustic look and the thinly layered formation of the stone. Like all stone tiles, slate has to be cut with a wet saw rather than a regular tile cutter. You’ll use unsanded grout when laying slate, to avoid scratching its natural surface.

Things You'll Need

• Trisodium phosphate
• Bucket
• Stiff scrubbing brush
• Mop
• Chalk snap line
• Carpenter’s square
• Thin set mortar
• Notched mortar trowel
• Slate floor tiles
• Tile spacers
• Wet saw
• Unsanded grout
• Grout float
• Sponge

Instructions

1. Mix 1/2 cup of trisodium phosphate in a bucket of warm water. Scrub the concrete thoroughly. Mop-rinse it. Let it dry three to four days.

2. Divide the cement floor into four sections, using your chalk snap line to lay two perpendicular lines that each cut the floor in half and intersect in the middle. Adjust the lines as needed against a carpenter’s square to ensure they are exactly 90 degrees off each other.

3. Spread thin set mortar over the intersection with your notched mortar trowel, covering enough area to encompass four tiles.

4. Set four slate tiles in place at the intersection, with spacers between them. Press them firmly into the mortar. Spread additional mortar and begin building outward, along the lines, in a grid pattern.

5. Tile the whole floor, putting spacers between all the tiles. Cut the partial tiles by the walls on your wet saw as needed. Wait at least one night.

6. Remove the spacers from the tiles. Grout the floor, starting at the far corner of the room from the entrance and working your way out. Use the grout float to press the grout into the spaces between the tiles, scraping it off the surface. Use a damp sponge to wipe up the excess grout. Let the grout set for 48 hours before walking on it.

Tips & Warnings

• Wear goggles when cutting the slate on the wet saw.

References

• Home Improvement Time: Floor Tiling