How to Seal Outdoor Slate Tile

  • 72-96 hours
  • Intermediate
  • 100-175
What You'll Need
Natural stone cleanser
Soft scrub brush
Slate sealant
Sponge roller
Painters tray
Rubber float
Lint-free cloth

It is vital that you seal outdoor slate tile during installation. This must be done before you apply the grout. If applied to unsealed slate tiles, the grout infiltrates the tiles and causes stains. Use a silicone-based sealer to give the slate higher resistance against moisture. This helps to maintain the slate in good condition which enhances the natural beauty of your home. Below is a guide on how to seal this tile.

Step 1 – Clean the Slate Tile

Prepare a solution of natural stone cleanser and water in a bucket. Use a soft scrub brush to clear away all dust and debris from the floor. This will leave you with a clean floor which is vital before you apply sealant. Rinse the floor well. Use water sparingly so that the floor doesn’t get saturated with water. Remove excess water from the floor with a dry mop. Leave the slate tile to air-dry for 24 hours.

Step 2 – Apply Sealant

Pour some sealant onto a painter’s tray. Begin application at one corner of the floor with a sponge roller. Apply sealant in short, even strokes to achieve uniform coverage. It is best to apply a thin coat as it attaches to the slate better. Too much sealant will collect in puddles and give you inconsistencies in appearance. Work your way from one corner and move across the width of the floor to the opposite corner. Steadily apply a thin, even coat as you move downwards until you complete the entire floor. Allow the sealant to dry for the stipulated time. An overnight wait is usually sufficient.

Step 3 – Apply Grout

Prepare grout as per the instructions that come with the product. Use a rubber float to apply grout along the joints. Press the grout firmly into the joints. Work in small sections. This way, you can wipe away the excess grout before it dries. Use a damp sponge to wipe away excess grout. Be sure to rinse the sponge in a bucket of clean water before you do each wipe. Change the water when it begins to look cloudy. Allow about 3 hours for the grout to cure. Wipe the floor with a clean, lint-free cloth. This removes residual grout which can give your slate tiled floor a hazy look.

Step 4 – Clean the Floor

Mop the entire floor with plain water. This will clear the floor of residual dirt and fine debris. Dry the floor with a dry mop. Allow 24 hours for the floor to air-dry in readiness for more sealant.

Step 5 – Add More Sealant

Use a clean sponge roller to apply sealant to the floor in the same manner as applied in Step 2. In most cases, 2 to 3 coats are required for higher efficacy. However, you must ensure that each coat dries completely before a subsequent coat is applied. It is best to apply sealant every 2 to 3 years. This helps to give your exterior slate tile floor higher protection against the elements.