A river rock floor looks like natural stone inserted into concrete. Instead, it is composed of thin sections of rock attached to a heavy mesh. This makes it easy to install and achieve a natural look with little effort.
Step 1: Prepare the sub floor as necessary. For a concrete slab, the area should be smooth, clean, and free of debris. Otherwise, you should install a layer of cement fiber board to ensure that the sub floor Is sturdy enough to withstand the weight of the river rock.
Step 2: Apply a layer of thinset over a small section of the floor using a notched trowel. Always start on a section of flooring that is the furthest away from the exit.
TIP: When choosing a thinset, be sure that you choose one appropriate to the floor you are installing. There are outdoor and indoor thinsets, as well as thinset used for high moisture applications.
Step 3: Place a sheet of river rock over the thinset. Lightly press the river rock into the thinset. Add another sheet of river rocks next to the first piece. Allow for a space between the tiles of river rock that mimics the space between the individual rocks attached to the sheets.
Step 4: Place a piece of plywood approximately 2 square feet over a section of the river rock. Hit the plywood with a rubber mallet, forcing the river rock into the thinset evenly.
Step 5: Continue installing sheets of river rock onto the sections of the floor until the entire floor is covered. Allow the thinset to cure for 24 hours before proceeding.
Step 6: Apply a penetrating sealant to the river rock. Due to the crevices inherant in the river rock, you will not be able to use a paint roller to apply the sealant. Instead, apply the sealant with a natural sponge while wearing gloves. This should create a coat that evenly coats the river rock. Allow the penetrating sealant to cure for at least 24 hours or as directed by the manufacturer.
Step 7: Apply a sand free grout to the crevices between the river rock with a rubber float in small sections. This will cover the mesh that holds the pieces of river rock together. Be sure to use enough grout to cover the mesh, but not enough to conceal most of the river rock and make the floor level. Wait 30 minutes before continuing.
Step 8: Remove the haze from the surface of the river stone with a damp sponge. Buff carefully until no grout remains.
Step 9: Continue applying grout and buffing away any grout haze after 30 minutes until the entire floor has been grouted. Wait 24 hours before continuing with this project.
Step 10: Apply another coat of penetrating sealant to the floor with a natural sponge. Allow the penetrating sealant to cure completely before walking on it.