How to Grout Outdoor Tile

Instructions

1. Clean the Tiles

   Use a utility knife to carefully scrape out any thinset mortar (the tile adhesive that you used to bond the tiles to the concrete slab) that may have squeezed out between the tiles when you set them. The thinset is a different color than the grout and can show through if it is not removed. Clean the surfaces of the tiles with a damp sponge.

2. Caulk the Expansion Joints

   Fill the grout joints that you have designated as expansion joints with a commercial silicone caulk or other flexible outdoor sealant designed for this application. Smooth the caulked joints with your finger so they will look like filled grout lines. Let the caulk cure overnight or as directed.

3. Prepare the Grout

   Mix cement-based grout in a bucket with water or a liquid additive, following the manufacturer's directions. Mix the grout thoroughly with a drill and mixing paddle, mixing only as much grout as you can use within the working time of the product. Let the grout sit, or "slake," for a few minutes, if directed by the mixing instructions. If you're using premixed grout, simply open the grout container; you do not need to mix or otherwise prepare the grout. However, you may need to moisten the tile surfaces with a damp sponge.

4. Fill the Grout Joints

   Plan to work in small areas, such as 3 by 3 feet, at a time. Scoop up some grout with a grout float and drop it onto the tile surface. Spread the grout over the tile faces and grout joints, holding the float at a 45-degree angle to the tile faces and moving it diagonally across the joints. Use the float to force the grout into the joints, making multiple passes from different diagonal directions.

5. Remove Excess Grout

   Hold the float nearly vertical (at 90 degrees) to the tile and scrape off excess grout from the tile faces, again moving diagonally across the tiles and grout joints. Moving parallel to the joints can pull out grout from the joints. Scrape the float against the edge of the bucket or container to clean the float as you work (you can use the removed grout on other tiles).

6. Sponge the Tile

   Fill a bucket with clean water. Wait the recommended amount of time (this varies by product), then wipe the tiles with a barely damp grout sponge (do not use a regular cleaning sponge) to clean the tile faces and smooth the grout joints. Make sure the sponge is just moist, not wet. The goal is to gently wipe the tiles clean while being careful not to remove grout from the joints. Don't worry about getting them perfect at this point; you will be wiping them again soon. Rinse the sponge frequently as you work.

7. Grout the Remaining Areas

   Repeat the same process to fill the grout joints and wipe the tiles in each small area over the entire tile installation.

8. Clean the Tiles Again

   Give all the tiles another wipe-down with a barely damp sponge. Rinse the sponge after every swipe to get the tile faces as clean as possible.

9. Remove the Grout Haze

   Let the grout set as directed, then buff the tiles with a microfiber cloth to remove the grout haze from the tile faces. You do not need to buff the grout joints. Allow the grout to cure fully, as directed by the manufacturer.

10. Seal the Grout (Optional)

    Seal the grout with an outdoor-rated grout sealer, using a sponge paintbrush or other applicator. You do not need to seal most premixed grouts, but this may be an option. Let the grout sealer cure fully, as directed.

Outdoor Tile Grouting Tips

One of the main challenges beginners face when grouting is the working time of the grout, or the amount of time you have before the grout starts to harden. If the weather is over 80 degrees F and/or there is direct sun hitting the tile, the grout may set up more quickly than the product's standard working time. For this reason, it's best to grout when the sun is not hitting the tile. If the weather is hot, start grouting in a very small area to get a feel for the actual working time before grouting over larger areas.