How to Build a Rock Sidewalk With Grout

Spray landscaping paint along the ground to mark out the two sides of your rock sidewalk.

Use a spade to dig an 8-inch deep trench between the sprayed lines. Compact the bottom of the trench with a tamper to level out the soil and create a steady base for the sidewalk.

Pour a 2-inch layer of gravel into the trench, covering the entire base. Compact the gravel with the tamper then pour and compact an additional 2-inch layer. The compacted gravel not only supports the rocks you’re using for the sidewalk surface but also provides drainage to avoid pooling along the sidewalk length.

Add a 2-inch layer of sand to the trench above the gravel layers to serve as a final support layer for the rocks. Compact the sand with the tamper as well.

Mix a batch of thinset mortar in a large bucket, adding enough water to the mixture to create the consistency of peanut butter. Spread the thinset over the sand with a trowel, creating a layer about 1-inch thick.

Apply mortar to the back of the rocks for your sidewalk with a steel trowel. Use rocks that have a flat side to serve as the sidewalk surface and place them so that the flat sides are as level as possible with the rocks surrounding them. Adjust the stones' level by pushing larger rocks deeper into the layer of mortar than thinner ones. Maintain a consistent space of about 1/5-inch between the rocks to allow room for the grout. Let the mortar cure for about seven days.

Mix the sanded grout, following the manufacturer’s directions. Cut the corner from a grout bag then fill the bag with the mixed grout. Pipe the grout between the rocks by placing the tip of the bag between two adjacent rocks and squeezing the bag to force the grout from the bag’s opening. Fill the spaces between the rocks to the surface with the grout, removing any excess grout with a damp sponge. Allow the grout to cure for an additional week.

Spray the sidewalk with stone sealant to prevent water stains on the rocks and grout. Cover the sidewalk with a moderate layer of the sealant, providing enough to penetrate the rocks liberally. Wait 48 hours, after sealing, before using the sidewalk.