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Grouting Slate Tile

Pull Up Your Socks and Follow These Tips for Grouting Slate Tile

Grouting slate tile correctly is an essential step toward minimizing water seepage and maintaining the durability of slate flooring. With careful do-it-yourself steps, you can easily grout slate tile floors like a professional.
Ningthoujam Sandhyarani
Last Updated: Dec 10, 2017
Did You Know?
The saying 'to have a clean slate' comes from old tavern menu writing slates that would be cleaned every day to put up new recipes.
Grout is used in the construction of buildings, flooring and sealing joints. It is a must for joining pieces of tiles together so they do not move from their designated places or location. Grout is made from water, sand and cement, depending on the requirements of the tiling. Grouting is a process by which the grout mix is applied to floor tiles to fix them in.
Installing slate tile floor is a sure way to enhance the elegance of any room, while you get the advantage of highly durable flooring. Nevertheless, during installation, make sure you purchase appropriate slate tiles of the correct thickness that suit the room temperature and foot traffic. Another advantage of slate tiles is that they have a slightly rough surface and are slip resistant even in wet conditions. Since they are easy to install, you can consider laying them on your own, as you do for ceramic tiles.
Steps to Grout a Slate Tile Floor
A tip before you start grouting, take up a smaller area, or a patch of the floor, about 8'X10', for grouting and not the entire area at one go. This is advisable simply because cleaning the entire floor at one go can be tedious and daunting, hence better to approach the task in small patches. Another concern is, purchasing an appropriate grout (or thinset), and grouting slate tile properly, so as to seal the tile surface and protect water penetration to the sub floor.
Step 1: Getting Started
Slate is not inferior to other tiling material, such as marble or granite or ceramic tiles, in terms of variety and versatility. It can be found in a variety of colors such as red, blue and green. It also gives a natural tint to the floor. Before you can start grouting your newly laid slate tiles, you must know which grout to use. A grout that is suitable for your floor will hold the tiles together better, and last much longer. Here are a few types of grout available in the market:
  • Unsanded grout: This is the simplest of grout, having a mix of water and cement. It is commonly used on small tiles in the range of 1/6th to 1/8th of an inch. Since unsanded grout adheres better than its sanded counterpart, it is often used on walls and other vertical surfaces.
  • Sanded grout: This type of grout has little particles of sand added to it to make the bond stronger. It is used on larger tiles and also for tougher tiling made from marble or granite.
  • Epoxy grout: Epoxy is a sealant, and when added to grout makes it water-resistant. It is best for bathroom floors and kitchen tabletops. It dries quickly and needs fast hands to apply.
  • Furan Grout: Furan grout is mostly used in industries and large laboratories because of its chemical resistant properties. It is mixed with a blend of polymers that give it such properties, but an expert or professional is required for proper application.
Once you have your choice of grout, you need to select your tools. There are various equipment used in the application of grout, such as rubber float, tile sealer, grout sealer, hand sealer, sponge mop, bucket and a paintbrush. You may also require a grout scraper if your old grouting work has stained, or is chipping away.

Step 2: Sealing the Tiles
  • Slate tiles are porous and hence there is a chance they might absorb the grout itself and, once hardened, might begin to look dull. It is necessary to read the manufacturer's instructions before any grouting work is done on slate tiles.
  • Another point to keep in mind, you must seal your tiles and not the grout. Water or moisture will get through sooner or later, if not through the grout then through imperfections in the tile itself. This is especially relevant for natural stone flooring such as slate or marble.
  • Make sure to seal the tiles first and then apply grout, to prevent loss of texture and shine.

Step 3: Applying Grout
  • Use a mask or air filter while mixing the grout in a bucket with a drill bit. The tiled area should be free of debris and other implements.
  • Take some grout mixture in your rubber float and spread it over the tiled area in sweeping motions at a rough 45 degree angle. Make sure the tiles have dried and the adhesive applied has had enough time to set in.
  • Add more grout and focus on the joints between the tiles.

Step 4: Wiping the Grout
  • Read the manufacturer's instructions carefully, and let the grout set for the recommended period of time.
  • Cover one joint at a time to grout the slate tiles properly.
  • After you complete grouting one portion of the slate tile, wipe excess grout before it dries out. This will save time while cleaning the slate tile floor.
  • Repeat the same to cover all the spaces, taking extra care while applying grout in the joint angles.

Step 5: Cleaning your Slate Tiles
Once the excess grout is removed, and it has dried, you can take a hand sander or floor buffer and run it over the tiled area a few times until the remains have been wiped away. A damp sponge will also do the job but be sure not to insert it between the tile joints, as this will remove the newly set grout or cause chipping later on.

With numerous grout sealing products available in hardware stores, the dilemma of whether to seal the grouted slate tile floor or not can be confusing. Many products claim to provide waterproof protection and extra strength to grout, but this can be misleading as the final results may vary. Slate tiles should be sealed before they are grouted and further sealing of the grout may not be required. However, a slate tile back-splash should be sealed as it is frequently exposed to water and moisture.
Make sure to follow these steps and refer to the grout instruction manual before you begin grouting slate tile floor on your own. Grouting can get messy and may leave debris and grain on your floor if not spread evenly, or if the mix is not prepared right. However, it is easy to do and small bathroom walls or kitchen tiles can even be grouted in a single day's work.