Slate is a great option for hard surface flooring for a number of reasons. It is extremely durable and stain resistant, and it also provides much more secure footing than standard ceramic tiles, which can become slippery when it gets wet.
Aside from durability, slate has a unique look that sets it apart from standard ceramic tiles and other man-made products. The face of a slate tile carries the natural texture that was formed when the slate broke away from the face of the rock. This gives you the opportunity to install a truly unique flooring solution.
What you'll need:
Inspect Your Materials
Before you begin any prep work, take a few minutes to inspect your flooring. Open up the crates and check the boxes for damage. Ask the company that you buy the flooring from what their policy is on broken or damaged tile. As you go through the crates, set aside any broken boxes and make sure that you get the appropriate credit from your supplier.
If you do end up having to send some boxes back, make sure that the replacements are from the same lot number. With natural products like slate, there are slight differences in hue and color that occur with in the rock. You need to make sure that your replacement pieces came from the same rock, or they may stick out once you have your floor installed.
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.
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.
Once the last pieces of tile are set, you can begin cleaning up the slate portion of your installation. Here a few key tips about clean up.
1. Clean the wet saw very well. Most rental companies will charge you an additional cleaning fee if you bring the saw back covered with muck and dust.
2. Dispose of your cut pieces carefully; we already discussed that they can be dangerously sharp.
3. If you have leftover tile, keep at least one box in a safe place. This is just in case you should ever drop a piano on your floor and have to replace a few tiles.
4. If you have leftover tile and you want to return it to the store and get some money back, do your best to pack it in full cases. Most places won't take back individual tiles, but will have no problem giving you credit for full cases.
5. If you did get any Thinset on the face of the slate, clean it up immediately. Unlike many tile adhesives, this does not clean off with solvents and it can be a real nightmare to get off after it has set up.
Grouting and Sealing the Floor
Now that your slate has been installed and the Thinset mortar has been allowed to dry for the amount of time recommended by the manufacturer, it is time to grout and seal the floor. Make sure that the grout that you have selected is sanded. You will need the additional strength that is provided by the sand in the grout because you have fairly wide gaps in between your slate tiles.
Mix the grout as specified on the package and begin spreading it over the slate using the grout float. Use the float to make sure there are no low spots between the tiles, and then use a damp rag to wipe any excess grout from the face of the tile.
In this process, we find one of the major differences between installing slate and installing traditional ceramic tile. With ceramic tiles, it is generally acceptable to allow a hazy film of to dry on the face of the tile between applications. Since the ceramic usually has a slick surface, this haze can be buffed right off with a damp rag. This is not the case with slate. Since the surface is porous, you need to make sure that the excess grout is cleaned up as soon as the grout is applied. Don't let it set up thinking that you can come back later and buff it off. Use your commercial sponge to wipe up as much of the wet grout as you possibly can. Once you are sure you've gotten it all, let the grout dry.
As the grout dries, you will begin to see a slight haze develop over the slate. Don't panic. As long as you got all of the grout paste up off of the tile, you should be able to wipe off any residual haze that forms as it dries. Make sure you use a dry towel to wipe off this residual film, as a wet rag or sponge will just smear it around more.
If, after your first coat of grout has dried, you see that there are some low spots, go ahead and give it a second application. This will ensure a uniform appearance once the floor has been sealed.
With most ceramic tiles, it is sufficient to seal just the grout. With slate, you are going to want to seal the entire floor. Check with your tile supplier about what stone sealers are recommended for your type of slate. This sealer can usually be applied with a paint roller or a handheld paint pad.
Keep in mind that the floor will require a bit of maintenance, as it will need to be recoated with stone sealer every so often.
No doubt about it, doing your own slate tile work is a big project. However, it is one that will pay huge benefits if you go ahead and do it yourself. Labor costs for tile professionals are extremely high and by putting in the muscle and time, you can save the money that would have been spent on a contractor and put it towards your next project.