How to Make Concrete Countertops With an Integrated Sink

Place the countertop form onto a flat surface with the drain side of the sink insert facing upwards.

Mix a batch of GFRC face mix in a bucket to the consistency of a thin milkshake. Use a drill with a grout mixing attachment to mix the water into the face mix thoroughly.

Fill a texture spray hopper with the mix and then turn the compressor of the hopper on to start the flow of air.

Hold the nozzle of the texture sprayer about 4 or 5 inches from the surface of the form and begin to cover the surface of the form and sink insert with a thin layer of the mix, building it to a thickness of about 1/8 inch along all surfaces.

Mix a batch of GFRC backer mix, which contains glass AR fibers throughout the mixture for added strength. Add enough water to the mix to create a high slump concrete with the consistency of mud.

Fill the rest of the form by hand with the backer mix, patting it in place to the rim of the concrete form. Cover the sink insert with the backer mix as well to a thickness of about 1/2 inch, smoothing the mix out as you go.

Place a layer of fiberglass mesh onto the flat area of the form after filling it to the halfway mark. Cut the mesh to fit using a utility knife. Continue to place the remaining concrete over the mesh, making sure to rub the concrete through all of the holes in the mesh to allow it to reinforcement the countertop. Do not cover the plug in the drain hole at the top of the insert.

Allow the concrete to cure between 10 days and two weeks.

Remove the form from around the edges of the countertop, and then pull the drain plug from the drain. Flip the countertop over so that the drain hole is pointed downwards. Remove the bottom sheet of the form from the countertop. The sink insert will come off with the bottom sheet, revealing the completed countertop with the integrated sink bowl.