Concrete countertops offer a unique, customizable option for homeowners looking to add character to their kitchens. These durable surfaces can be tailored to fit any space and style, making them an attractive alternative to traditional materials. In the above video, concrete fabricator Peter Somers walks This Old House host Kevin O’Connor through the process of building a custom concrete countertop.
Benefits of Concrete Countertops
Concrete countertops offer many benefits, making them popular in modern and traditional kitchens.
- Customizability: Concrete allows for extensive customization. It can be molded into various shapes and sizes and colored or textured to suit different styles. This flexibility enables the creation of unique, personalized countertops.
- Design flexibility: Concrete can be combined with glass, metals, or natural stone to achieve distinct patterns and finishes. Integrated features such as sinks and drainboards can be seamlessly included, offering a cohesive and streamlined appearance.
- Durability and strength: Concrete countertops are highly durable and withstand heavy use, scratches, and impact. When properly sealed, they resist stains and moisture, making them ideal for high-traffic areas.
- Eco-friendly options: Concrete countertops can be made with recycled materials and low-VOC sealers, offering a sustainable option for environmentally conscious homeowners.
- Low maintenance: After sealing, concrete countertops are easy to maintain with regular cleaning using mild soap and water. They may need periodic resealing to preserve their resistance to stains and moisture.
Tools and Materials Needed for Custom Countertops
You’ll need the following tools and materials for your countertop project.
Tools
- Air-powered sprayer
- Angle grinder with diamond-impregnated cut wheel
- Clean rag
- Electric drill (1/2-inch) with mixing paddle
- Flat bar
- Hammer
- Miter saw
- Random-orbit sander
- Sanding block
- Table saw
- Wet grinder with diamond pad
Materials
- 1/4-inch plywood
- 1-inch-thick rigid polystyrene foam board
- 1x3s (for securing foam)
- 2-inch-wide strips of melamine-faced particleboard
- 2 1/2-inch-wide strips of plywood
- Additional pigment (for slurry)
- Beeswax
- Cement
- Clean rag
- Concrete sealer
- Construction adhesive
- Glass fibers
- Liquid polymer
- Powdered pigment
- Sand
- Silicone sealant
- Steel-wool pad
- Stone aggregate
Planning and Preparation for Concrete Countertops
The first step in building custom concrete countertops is creating an accurate template of the existing countertop space.
Create a Template
- Use 2 1/2-inch-wide strips of 1/4-inch plywood to outline the countertop area.
- Adhere the plywood strips together using hot-melt glue.
- Label each template section to identify its position on the cabinets.
Build the Form
Next, you’ll create the form which serves as a mold for your concrete countertop:
- Use a melamine-faced particleboard as the base for your form.
- Cut 2-inch-wide strips of particleboard for the sides of the form.
- Place the template upside down on the melamine board.
- Hot-glue the 2-inch-wide strips around the perimeter of the template.
- Miter-cut the strips at inside corners and seal the joint with silicone sealant.
- Remove the template, then wipe beeswax around the inside of the form.
- Apply a bead of silicone sealant along all inside corners and perimeter edges of the form.
- Smooth the silicone with a length of 3/8-inch-diameter plastic dowel.
- Once the silicone has cured, peel off the excess.
Mix and Pour the Concrete
Follow this guide to properly mix and apply your concrete.
Mix the First Concrete Batch
This first batch will create the surface layer of your countertop. For the initial layer, combine the following:
- Sand
- Cement
- Liquid polymer (for increased strength)
- Powdered pigment (for color)
Mix these ingredients thoroughly using a 1/2-inch electric drill with a mixing paddle.
Apply the First Layer
Instead of pouring this initial mix, you’ll spray it into the form:
- Vacuum the form clean, then wipe it down with a clean rag dampened with acetone.
- Use an air-powered sprayer to spray a 1/4-inch-thick layer of concrete into the countertop form.
- Sprinkle a contrasting-color stone aggregate into the wet concrete to add visual interest.
Add Strength and Bulk
For the main body of the countertop, prepare a second batch of concrete:
- Mix the same ingredients as the first batch.
- Add glass fibers to increase the strength of the countertop.
- Pour this mix into the form in layers, about 3/8 inch thick at a time.
- Use a hand roller to compact each layer, removing air bubbles.
- Compact the concrete with a hand roller. Add another 3/8-inch of concrete and compact it again.
- Cut 1-inch-thick rigid polystyrene foam board 3 inches smaller than the inside of the form.
- Lay the polystyrene foam on top of the wet concrete.
- Screw 1x3s across the form to hold down the polystyrene foam.
- Pour concrete around the perimeter of the polystyrene, filling it flush with the top of the particleboard form.
Finishing Touches for Your Countertop
The final steps in creating your concrete countertop involve curing, removing it from the form, and applying the finishing touches. Use the steps below to complete your project.
Cure the Concrete
After pouring, allow the concrete to cure for three days. This allows the countertop to reach its full strength before removal from the form. To promote an even set, avoid disturbing the form or applying any weight to the countertop during curing. If possible, maintain a consistent temperature and humidity level to prevent cracking and achieve a smooth finish.
Remove From the Form
Carefully remove the countertop from the form:
- Unscrew and remove the 1x3s.
- Smooth the concrete using an angle grinder equipped with a diamond-impregnated cut wheel.
- Pry off the polystyrene foam board with a flat bar. Vacuum the surface clean.
- Use a hammer and chisel to remove the particleboard form from around the perimeter of the countertop.
- Round over the sharp countertop edges with a sanding block.
- Tap a wide-blade putty knife underneath the countertop, then insert a wood shim.
- Repeat in several places around the perimeter until the countertop breaks free from the particleboard form.
- Flip the countertop over once it’s free from the form.
Polish and Seal
The final steps involve refining the surface and protecting it:
- Lightly grind the top surface with a wet grinder and diamond pad. Continue grinding until you’ve exposed the aggregate.
- Mix cement, polymer, and pigment to create a slurry. Hand-rub the slurry into the entire countertop.
- Wait for the slurry to harden.
- Smooth the entire countertop surface and edges with a random-orbit sander fitted with an 80-grit abrasive disk.
- Switch to 100-grit abrasive and sand the surfaces again. Switch to 220-grit abrasive and smooth the countertop one last time.
- Use a steel wool pad to apply a concrete sealer to the countertop. Let dry for 10 minutes, then apply a second coat.
- Repeat until you’ve applied eight coats of sealer.
Final Installation
Once your countertops are polished and sealed, they’re ready for installation:
- Carefully transport the countertops to their final location.
- Apply a bead of construction adhesive along the tops of the cabinets.
- Set the countertops in place, making sure they’re level and properly aligned.
Personalize Your Countertops
Concrete countertops offer a great opportunity for personalization. Consider embedding decorative items such as shells, sea glass, or colored stones into the surface before it fully sets. This adds a unique, personal touch that reflects your style. For a cohesive look, choose items that complement the overall design of your kitchen or bathroom.
Experiment with different patterns or arrangements to create a unique custom design. Keep in mind that larger or heavier items may need to be carefully embedded to keep them in place during the curing process.
