Install a Slate Floor 2 - Installing the Slate

Prepare the Underlayment

After you have inspected your materials and are comfortable with what you have, it's time to begin your prep work. You will need to make sure that all of the baseboard and quarter round is taken up from the perimeter of the room. If there was carpet installed previously, then you will also need to take up the tack strip from around the edge. (This is Part 2 of a 3 part series. Click to view Part 1 or Part 3.)

When the floor clean and free of obstructions, you can begin putting down the underlayment. This is a crucial step, so don't cut short the quality of the work that you do here. The cement based underlayment creates a foundation for your slate to sit on. You need to make sure that it does not flex. Any flex or rocking motion in the floor will cause the slate tiles to come loose and the grout to crack. The best way to ensure that the foundation is solid is to follow the manufacturer's exact instructions for installing the underlayment. Most brands are engineered to be screwed down with a specific pattern. Follow it to the letter.

Plan Your Tile Layout

Once the subfloor is set, secure and ready to go, the next thing you need to do is establish the center point of your room and lay out some guidelines. Use your tape measure to find the center of each wall and mark it on the floor. Use the chalk line to snap a line between those points. The place where the two lines intersect is the center of the room.

Before you mix any mortar, begin laying out the tile so that you can establish the pattern. There should be a sketch of the recommended pattern attached to the crates that the tile came in. Once you are comfortable with the pattern and have a better idea about spacing, then you are ready to move on.

At this point, you have one more task to accomplish before you mix mortar. Take a look at all of the doorjambs that lead into the room. Is there space at the bottom to slide the slate underneath? Unless you took up a hardwood floor or removed old tile first, then probably not. Take a piece of your new slate and set it down next to the base of the jamb. Draw a pencil line on the jamb along the top of the tile. Use your saber saw with a nice long blade to slowly cut away the bottom of the jamb. You will be surprised at how easily the piece pops out. Once the bottom of the jamb has been cut away, you should be able to slide the slate underneath the jamb, creating a clean, professional looking edge. Repeat this step for every facing jamb in the room.

Apply the Mortar and Slate

Finally, you are ready to begin mixing mortar and laying tile. It is a good idea to mix a small batch of mortar at first so you can get a good feel for how fast you can work. Nothing is more frustrating than mixing up a big batch of mortar, only to have it start to harden in your pail before you get a chance to use it. The instructions about how much water you should add should be on the package.

Once you have a small batch of mortar ready to go, begin working along the gridlines that you snapped with the chalk line earlier. Use the trowel to spread the mortar in small sections and set the tile fairly quickly. Take care not to get any of the Thinset on the face of the tile, as it is very aggressive and can be difficult to clean off. Work slowly with your gridlines, making sure that your spacers are straight and that each pattern repeat fits uniformly with the others. The key to making sure that the patterns fit together properly is spacing. The spacing between each tile must be identical or the repeats won't mesh together.

Cutting Slate Tiles

When you get to the edge of the room, you will need to begin cutting the slate to fit next to the wall. This is the job for the diamond bladed wet saw. It may seem like a large expense in order to just cut a few tiles around the edge of the room, but if you've ever tried to cut slate by hand, then you know that it is well worth it. Measure each cut carefully, making sure you take into account the spacing necessary to make the appearance of the tiles consistent. Mark each tile on the back with a pencil, and then cut it on the wet saw.

Keep a few safety tips in mind as you use the wet saw. First, always wear safely glasses. These machines can spit out a lot of residue and you don't want powdered slate in your eyes. Second, be careful of the edges of the cut tiles. The diamond blade leaves a very sharp edge when it cuts the slate. The tile will be wet right after you cut it and so will your hands. Don't let the wet tile slide through your fingers or you may end up with a nasty cut. Lastly, the wet saw is an electric power tool that uses a tub full of water. Typically, this water starts to end up on the floor as you progress with your work. Make sure the plug is safely out of the way of the water spray and that you aren't standing in any puddles while working.

Make sure that you don't save the pieces that go under the door jambs for last. If you do, you won't have any room to slide them under the jamb. Install the jamb pieces first, and then work the cut pieces around it.

Continue to Part 3: Grouting and Clean Up >