What kind of grout to use on slate?

When installing slate tile, choosing the right grout is an important decision that will impact the look and durability of your flooring. The grout fills the joints between slate tiles and locks the tiles in place. Using the wrong type of grout with slate tile can lead to staining, cracking, and other problems down the road.

What are the different types of grout?

There are three main categories of grout available:

• Cement-based grout – This is a mixture of Portland cement, sand, and other ingredients. It provides a strong bond but can be prone to cracking and color inconsistencies.
• Epoxy grout – Epoxy grouts contain epoxy resins and a filler such as sand or silica. They are extremely durable, resistant to stains, and come in a wide range of colors.
• Urethane grout – Urethane grouts contain polyurethane resins. They are flexible, waterproof, and resistant to chemicals.

Within each category, there are different grout formulations available that offer various performance properties.

What factors should you consider when choosing grout for slate tile?

When deciding on the best grout for your slate tile, there are several important considerations:

• Color – You’ll want to choose a grout color that matches or complements the color of your slate. Natural gray shades are popular choices.
• Width of slate tile joints – The width or spacing between slate tiles will impact what grout types will work best. Wider joints may require more flexible grout.
• Location – Is the slate tile being installed in a wet area like a bathroom or kitchen? Moisture-resistant epoxy or urethane grouts are best for wet areas.
• Foot traffic – Areas with heavier foot traffic need grout that can withstand daily wear and tear without cracking or crumbling.
• Exposure to chemicals – Grout needs to be resistant to any household chemicals it may come in contact with, like cleaners or bleach.

What is the best grout for slate floors?

For most slate floor tile installations, an epoxy grout is the best choice. Here’s why:

• Extremely durable and stain resistant
• Available in a wide range of colors to match slate tile
• Resists mold and mildew growth
• Withstands heavy foot traffic without cracking
• Easy to keep clean

Epoxy grouts are made of tough epoxy resins that cure to a hard finish. This prevents staining, resists damage from impacts, and won’t be affected by moisture. Epoxy grouts come in various colors to match or accentuate slate floors.

For slate tile with wider grout joints, flexible “soft” epoxy grouts are a good option. The flexibility reduces the chance of cracking. Urethane grouts also provide flexibility for wider joints.

What’s the best grout color for slate floors?

Choosing a grout color that matches or contrasts nicely with the slate tile is important for the look of the finished floor. Here are some popular grout color choices for slate floors:

• Natural gray – Matches most slate tile colors for a seamless look.
• White – Provides contrast against dark charcoal slate colors.
• Black – Makes light gray or green slate tiles pop.
• Dark gray – Complements medium to dark slate tile colors.

Be sure to look at grout color charts and compare to the actual slate tile before deciding. The grout should match the undertones of the slate to avoid clashing. Go with a darker shade for a subtle contrast or lighter for more pop.

What’s the best way to apply and grout slate tile?

Proper application of grout into the joints of slate tile is crucial for a lasting finish:

1. Use a premium quality thinset mortar suitable for natural stone when setting the slate tiles. This provides maximum adhesion.
2. Apply grout sealer to the slate tile before grouting. This prevents staining of the slate surface.
3. Use a rubber grout float and work the grout thoroughly into the joints, packing tightly to avoid air pockets.
4. Wipe diagonally across the joints to remove excess grout and shape the joints.
5. Clean any remaining grout haze off the slate tile surface with a sponge and pH neutral cleaner.
6. After curing, apply grout sealer to protect joints and enhance stain resistance.

Following these application tips will give you clean, uniform grout lines that are attractive and long-lasting.

Can you use sanded grout on slate tile?

Sanded grout contains fine sand or silica particles that help fill in wider joints and provide a stronger finished joint. However, the sand can scratch more delicate natural stone surfaces like slate during installation.

For slate tile, it’s best to use an unsanded grout. Unsanded grouts are smoother, reducing the risk of surface scratches. They are ideal for grout joints 1/8 inch or smaller typically found with slate tiles.

If wider grout joints are needed for a unique slate pattern, use a “soft” epoxy grout that contains fine aggregates rather than sharp sand. This allows wider joints up to 5/8 inch while minimizing scratching or damaging the slate tile surface during application.

How do you seal grout for slate tile?

Sealing the grout after installation is highly recommended to protect slate floors. Here are tips on choosing and applying grout sealer:

• Use a penetrating sealer formulated for grout rather than a surface coating.
• Apply sealer to clean, dry grout joints per manufacturer instructions.
• Use an angled applicator bottle to target sealer into the grout lines and edges.
• Wipe off any excess sealer from the slate tile surface.
• Allow sealer to cure fully before washing the floor.
• Reapply grout sealer every 1-2 years for continued protection.

Sealed grout resists staining, reduces mold/mildew growth, and makes routine cleaning much easier. Grout sealers may also make the joint color more uniform.

How do you clean grout on slate tile floors?

Regular cleaning keeps your slate and grout looking their best. Here are some tips:

• Vacuum or sweep floor frequently to remove dirt and grit from grout joints.
• Mix a pH neutral tile & grout cleaner with water per label instructions.
• Use a stiff nylon bristle brush to scrub the grout joints and loosen staining.
• Rinse thoroughly until water runs clear.
• Once dry, seal any new unsealed areas of grout exposed during cleaning.

For stubborn stains in porous grout, use an oxygen-based bleach cleaner designed for natural stone and grout. Always test cleaners first on an inconspicuous area.

Resealing the grout once a year will make regular maintenance cleaning easier. Avoid harsh acidic cleaners which can damage grout over time.

Can you change the color of existing grout on slate tile?

If your existing grout has become discolored or stained over time, the color can be changed:

• Use a grout saw or Dremel tool to cut out old grout at least 1/8 inch deep.
• Vacuum out all debris and apply new matching grout into joints.
• Another option is to apply a grout colorant per manufacturer instructions without removing old grout.
• Grout colorants sit on top of the grout joint vs. changing the color throughout.
• Colorants last 1-3 years before reapplying is needed.

Always test grout colorants in an inconspicuous spot first. Change the entire floor’s grout color for most consistent results. Make sure any new grout matches the old in terms of type and performance.

Can you use epoxy grout over existing grout?

Installing epoxy grout over existing cement grout is possible in some cases to improve stain resistance and appearance:

• The existing grout joints must be clean and free of cracks, damage, or powdery areas.
• Use a grout saw to cut out any loose, crumbling grout so new epoxy has a solid base.
• Wash the floor with a pH neutral cleaner and let dry completely.
• Apply epoxy grout per manufacturer instructions up to existing grout line.
• Take care to pack epoxy tightly into joints for good adhesion.

The epoxy will bond to old grout if the joints are stable and properly prepped. Avoid overlapping onto the slate tiles which can be hard to remove once cured.

Replacing all old grout ensures the best results, but epoxy can be a cost-effective grout upgrade alternative in some slate floor renovation projects. Always test in an inconspicuous area first.

Conclusion

Choosing the optimal grout for your slate tile floors involves considering color, slate joint size, location, traffic, and other factors unique to your space. In most cases, epoxy grout is recommended for its durability, stain resistance, and color consistency with slate. Proper application and sealing of the joints will protect your slate investment for years of beauty and enjoyment. Don’t be afraid to get creative with grout color choices to make your slate floors truly one-of-a-kind.