How to Grout a Stone Tile Floor

Grouting a Stone Tile Floor
Grouting can be rewarding because it means you're almost done with your tile project. The flip side is when something goes wrong and you use the incorrect type of grout or ruin your expensive stone tiles by making a mistake. Here are some important tips for grouting a stone tile floor.

Seal the Stone Before Grouting

Natural stone is porous to some degree, which means it can absorb liquids into its pores and tiny fissures. While grout wipes right off ceramic tile, the same cannot be said of natural-stone. You must seal natural stone tile, including marble, limestone, granite, and slate, before applying the grout. If you don't, the grout could be absorbed into the tile and ruin your finish. To seal the stone, spray a stone-safe granite sealer in 3-foot sections, immediately wipe it into the stone with a lint-free cloth, then buff it dry. Make sure you let the seal cure for about 24 hours before you start grouting.

Choose the Right Type of Grout

There are several types of grout available, each with benefits and drawbacks. The most common types of grout are sanded and unsanded. Unsanded grout is a cement-based grout product mostly used for smaller projects with a grout joint spacing of 1/16" to 1/8". Sanded grout is usually used for larger joints with sand grains that offer greater strength, and it is typically recommended for heavier natural stone because the sand increases the strength of the bond. Another option is epoxy grout. Unlike cement-based products, epoxy is nonporous and creates an impermeable barrier to water. When you use epoxy grout, you do not need to seal the grout lines, and it can also limit cracking because it tolerates some movement. However, there are two downsides to epoxy: it sets quickly and it's more expensive than cement-based grout.

Apply the Grout Carefully

Before you start grouting, make sure the mix has a creamy consistency like mayonnaise. Always let cement-based grout rest for 10 minutes and mix again by hand before applying it. This allows all dry materials to get wet. When you're ready to grout, sweep the grout diagonally across the grout lines using a grout float held at a 45-degree angle. Force the grout completely into each joint before wiping the excess grout off the surface. Work in small sections to prevent the grout from hardening. After filling the joints, let the grout rest for about 30 minutes, then tool the grout lines. The goal is to create a slightly convex surface without lumps or smears. Use a sponge that is damp—not wet—to remove grout from the surface of the tile.

Seal the Grout

The last step for your project is applying grout sealer. This should be done 24 hours after the grout dries. Grout sealer keeps the grout clean and prevents stains that could detract from the appearance of your stone floor. The sealer also keeps water from penetrating the joints and reaching the backing. Note that grout sealer only needs to be used with porous, cement-based grout, not epoxy-based grout. Keep your stone floors looking as good as new with the help of a high-quality cleaning product such as Granite Gold Squeeze & Mop Floor Cleaner®. All products made by Granite Gold® are safe to use on granite, slate, marble, quartz, and other types of natural stone. Call 1-800-475-STONE today to learn more.

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