How to Prepare a Subfloor for Terrazzo Tile
Before you can install floor tile, there must be a viable subfloor that the tiles can adhere to. Follow these step-by-step instructions to prepare a wood subfloor for tilework.
Terrazzo is composed of marble chips and/or dust with a cement binder. It is available as finished individual tiles or as poured in place over a concrete slab, and then ground to the polished finish. When using tiles, many contractors try to replicate the look of the slab terrazzo by butting the tiles up against one another.
After taking measurements, dry fit the first row of full tile from the chalk line to the outside wall; lay out and mark the last row of tiles that will need to be cut to fit. To determine the tile cuts, you can use a technique called "jump scribing," which is simply to overlay the second tile from the wall and scribe a line down the first tile for the cut as shown in the image.
Use a diamond-edge wet saw to cut any tiles that need to be cut to fit. A wet saw, which costs about $40 - $50 to rent, creates a clean and smooth tile cut.
After you have dry-fit all of the tiles, spread a thin layer of wet-set adhesive onto the floor using a 1/16" square notch trowel. Don't cover the chalk mark you made with the adhesive -- spread the adhesive up to the line instead of over it.
Let the adhesive set for a few minutes until it's tacky (read the directions specific to adhesive product).
Starting at your middle line and working toward the outside wall, lay the first row of full tiles, placing the tile firmly into position, butting each one snugly up against the next so there is no joint.
Check that the tile is flat and level and square to the chalk lines. You may need to press the tiles into the adhesive or to gently tap them with a rubber mallet.
Next, lay the outermost row of cut tiles into place. Once this has been done, proceed laying the rest of the tile in the same manner.
If you're working in a kitchen or utility room, be sure to tile underneath appliances such as the dishwasher, refrigerator or washer so that the floor won't be damaged in the event of a leak.
Once the tiles have set well into the adhesive and are beginning to become difficult to move, roll the floor with a 150-lb. roller to ensure that the tile and adhesive have bonded completely.
Let the tiles set and the adhesive to dry for at least 12 hours before walking on the tiles. Then apply a sealer to the tile floor.
A good rule of thumb for choosing a sealer for your terrazzo floor. Working with the store merchant from whom you bought your tile, choose a sealer for the least absorbent of the marble chip components. That way you seal the stone without building up sealers on the denser marble chips.
When all the tile is sealed and the seal is completely dry (read directions), sweet the floor with a broom and run a light mop over it to test the sealer. Water should bead up on top of the sealer.