How to Make a Concrete Vanity Top
Keep your bathroom looking and feeling cool with this unique concrete vanity top. Instead of a sleek marble or granite countertop, concrete adds an industrial feel to your bathroom. It looks great mixed with silver and holds an interesting juxtaposition against a wood floor. Custom-make your own concrete vanity top with our easy-to-follow instructions below.
What You Need
- Drop-in sink
- Tape measure
- 1/2-inch-thick melamine board
- Table saw
- 2-inch-thick rigid foam insulation (a bit larger than your vanity base)
- Medium-grit sandpaper
- Packing tape
- Silicone caulk
- 3/16-inch rebar
- Galvanized-steel hardware cloth
- Florists wire
- Countertop concrete
- Plastic concrete-mixing tub
- Shovel for mixing concrete
- Nonstick cooking spray
- Plastic drop cloth
- Protective gloves
- 2x4 board
- Utility knife
- Concrete sealer (we used Safecoat Acrylacq in satin)
Step 1: Make Concrete Form
To measure for concrete form, measure the top of your vanity and add 1-1/2 inches on each side and front for a lip.
To make form, cut melamine board to the dimensions determined above. Make a frame with pieces that are 2-1/2 inches tall; you want your countertop to be 1-1/2 inches deep, so measure to accommodate melamine board thickness. Predrill holes, then screw on side melamine pieces.
Step 2: Trace Sink
Next, use a marker to trace the outline of the drop-in sink onto the rigid foam insulation. For later reference, trace the sink hole openings as well. Be sure to hold the sink steady as you trace to get the most accurate markings.
Step 3: Cut Foam
Using a measuring tape, mark the inside of the sink tracing to shrink it to about 1 inch smaller, or however much smaller the lip of your sink is so that the sink will sit in the opening without falling through.
Cut the foam using a jigsaw on the slowest setting. You should cut along the markings of the inner circle. Sand the edges of the foam to create a smooth edge.
Step 4: Wrap Edges
Put a strip of packing tape around the edge of the rigid foam insulation to create an easy-release surface. Be sure to get large packing tape with a handle for the easiest application. If your tape isn't wide enough for the whole edge, go around the foam core again to make sure all is covered.
Step 5: Position Foam
Find the center of your form; this is where your sink will be. Use silicone caulk to glue your rigid foam insulation cutout where the sink will sit, and then use a drill to secure the melamine board form to keep it in place. Use scrap wood to float on top of insulation to ensure the screws don't sink into the insulation.
Step 6: Caulk Edges
Run a bead of silicone caulk around the edges of the melamine board and the edge where the insulation cutout meets the melamine board, making sure there are no gaps for the concrete to leak out. Use your finger to smooth the caulk.
Step 7: Assemble Rebar and Mesh
Cut four pieces of rebar (two 24 inches and two 20-1/2 inches) and wire together using florists wire. Cut hardware cloth into two pieces 20x8 inches and attach to opposite sides of rebar square. Secure everything with wire so the pieces won't shift when you add them to the concrete. Set aside.
Step 8: Pour Concrete
Spray the form with cooking spray so the concrete will easily separate from the form when cured.
Mix the concrete in a plastic tub using a shovel, then pour into the form, filling about halfway. Place rebar and mesh on top. Then fill the form the rest of the way with concrete while smoothing with a trowel.
Editor's tip: Before pouring concrete, cover your work space in a plastic tarp to protect from drips. Also wear protective gloves.
Step 9: Smooth Top
Next, run a smooth 2x4-inch board over the form. Be sure the board is wider than the vanity top so both ends can rest on the form structure while you smooth. Because the top of the form will end up being the bottom of your countertop, it should be smooth and level so it sits nicely on the vanity base.
Step 10: Let Cure
Lay a plastic drop cloth over the top of the form and let cure for a week. The drop cloth slows the curing process, which makes for a stronger concrete top.
Step 11: Remove Concrete
Remove the concrete top by unscrewing the sides of the melamine form. Then remove the insulation cutout piece with a utility knife.
Step 12: Install Vanity Top
Apply a bead of clear silicone to the rim of the vanity base, then place the concrete on top and drop in the sink.
Seal the concrete with a concrete sealant.
Editor's tip: When selecting your silicone, choose a clear solution that is mold- and mildew-resistant.