Doing some things around your house by yourself is a great way to get several high-end home features without increasing the base cost of the home. One feature most can take is concrete countertops.
When planning kitchen renovation, stone countertops can cost quite a bit. The composite materials for the kitchen and baths can cost anything from around $1000 to upwards. Granite materials can cost even more.
If you have any DIY spirit in you, making countertops to your house can drop the price to a third. Even less depending on what you have to buy yourself. Here is a short tutorial how to achieve that yourself.
Step 1: concrete countertop template
It’s good to plan ahead with cheap materials. If you can get your hands on second-hand card-boards, they might be a good solution. Lay them on top of your cabinets where the concrete countertops would be and cut them as you desire. After you have the templates, you’re ready to proceed.
Step 2: concrete countertop form
Using the cardboard cutouts as patterns, trace them onto 4′ by 8′ sheets of ¾” melamine coated particleboard. Once the melamine sheets are cut to the shape of the concrete countertops, sides need to be attached to form a mold.
Use a table saw to cut several 2 ¾” strips of melamine for 2″ thick concrete countertops. If a thicker or thinner countertop is wanted, add ¾” to the desired thickness. Nail, staple, or screw the strips of melamine into the edge of the melamine form. The form will look like a shallow box.
Next, determine where any sink or faucet openings will be required. You can use a 2″ thick foam insulation board for the sink and faucet voids. Wrap the edges of the insulation with 2″ acrylic tape. Stacked plywood cutouts work well also.
With the foam insulation, a few beads of liquid nails or other adhesive is used to attach the cutout in the correct spot on the form. With plywood layers, screw the first layer into the melamine form. Then stack the next layer and screw it into the previous layer until the height matches the edge height of the mold.
The final step in concrete countertop mold preparation is to run a bead of silicone adhesive between all inside corners of the mold. A piece of ½” PVC pipe pressed against the bottom and side of the form and dragged across the silicone bead will leave a nice rounded edge. Be sure to caulk around the sink and faucet voids.
Step 3: concrete countertop reinforcement
For reinforcing material you can use 3/8″ rebar. Metal lath or concrete mesh will also work, but it is recommended to use rebar near the sink where extra strength is required. The melamine surface at the bottom of the mold will be in contact with the top surface of the concrete countertops. It is important that no reinforcement material is in contact with the bottom of the mold.
You can span two by four across the mold. Then with thin wire suspend a rebar matrix from the two by fours. After the concrete countertops are dry the wires are cut flush with the bottom surfaces. Rebar matrix can have bars crossing in a one square foot pattern with tie wires at each intersection.
Step 4: concrete for concrete countertop
For dark-colored concrete countertops, high strength concrete mix with fiber reinforcement is the way to go. The mix is available at home depot. For lighter colored countertops, white Portland cement and light sand will be required to make your own concrete mix. Home Depot carries several colors of concrete dye powders in one-pound boxes. For custom colors, a masonry supply store will need to be contacted.
I’ve mixed one box of concrete dye powder per bag of concrete. You may want to make several mini-batches to get the final color you want. I saved my test batch samples and wrote the mix ratio on the underside for future reference. Mix the concrete per the direction on the bag. Pour the concrete and screed until the form is full.
Step 5: concrete countertop form vibration
Once the form is filled it is imperative that the concrete be agitated. There are several ways to do this. The easiest is to rent a stinger which is a device designed to vibrate wet concrete. The vibration causes any trapped air to rise to the surface.
Any air bubbles left at the bottom of the mold will result in a small hole in the concrete countertop surface or on the edges. A rubber mallet with a lot of pounding on and against the sides will also remove air bubbles. This method will save the rental cost but will leave you tired. A lot of pounding on the form will be needed, at least an hour.
The method I’ve used before was an air hammer. I put a rubber plug over the end of an air hammer tip and proceeded to pound the form at the base of the sides. I continued to pound around the perimeter of the form for about a half-hour.
Once all bubbles are removed, allow the countertops to dry and cure. Depending on climate and temperature, this may take two to three days or more than a week.
Step 6: concrete countertop installation
Gently pry the sides off of the concrete countertops form. With help, lift the concrete countertops, rotate them, and lay them onto the cabinets with the smooth surface facing up. After the test fit, remove the countertop and run a small bead of liquid nails or construction adhesive along the top edge of the cabinets. Lift the concrete countertops and set them in place on the cabinets.
Optional step: sand the surface of the counter. It will make it smoother and if there are rough spots, they will level a bit. You can use some sanding tool to help you, have one with a vacuum attachment so it won’t be so dusty. You can also further dye your concrete.
Use a deep penetrating concrete sealant from a masonry supply store to seal and waterproof the concrete countertops. For a high luster shine, I polish with a 100% Carnauba car wax every six months.
To complete the install, make a tile backsplash and you’re done. You will have the satisfaction that comes only from a do-it-yourself job done right. Enjoy the great money savings from not paying for expensive labor and the high-end look of concrete countertops.
This is one way more to build a concrete countertop. Situations are different and sometimes one way to build it won’t work, that’s why it’s good to have multiple ways to do it.
There are also different ways to decorate them, here is a guide on staining concrete countertops.