Last Updated on
Of all the kitchen countertop materials out there, few are as disputed as the high-end concrete. When it comes to the physical characteristics, concrete kitchen countertops are as rock-solid as granite and slate. They can be a better fit in many modern homes than their stone or manufactured counterparts. When made by skilled contractors, concrete exudes a rustic industrial aesthetic and lasts for years. Therefore it should come as no surprise that they are gaining popularity in farmhouses. On the other hand, concrete also has some significant downsides if you are considering getting one. If you still wish to go ahead and build one on your own, this article will guide you through the process.
How to Make Concrete Countertops?
Here is how to make DIY concrete countertops.
Here are the tools you will need to build your concrete countertop. If you do not own some of these, you can rent for the day.
- Concrete mixer
- Concrete mixing tub
- Table saw
- Miter saw
- Power drill
- Drill bit sets
- Tape measures
- Masks and respirators
- Microfiber cloth
- Caulk gun
- Drywall taping and joint tool
These are the materials you need to have ready:
- Cement and concrete mix
- Painter’s tape
- Melamine MDF board 3/4th inch thick (full)
- Caulk and sealants
- Power sanding disc of different grits
- Re-bar and re-mesh
- Wood screws
- Concrete sealers
- Framing lumber
- Plastic sheeting
The process of forming concrete countertops can be divided into six steps:
Building the Mold
The mold acts as the structure to which concrete is poured to make the countertop. Remember that making the countertop thicker also increases its height. Additionally, some building codes require a space of 18 inches between the countertop and the bottom of the cabinets. Follow these instructions to make the mold:
- Place the ¾” melamine MDF sheet over two sawhorses. The sheet should be slightly bigger than the dimensions of the countertop and its mold combined. Place a few 2’x6” lumbar boards under the mold to support the final weight and avoid sagging.
- Mark the dimensions of the countertop on the MDF board with a marker. If you intend to have a sink in the countertop, mark that as well.
- Make the mold’s sides (to hold the cement inside) by cutting strips using more MDF boards. The side’s inner dimensions should be the final dimension of your countertop. The side’s thickness should be the same as the thickness of the countertop.
- Place the side strips over the marked MDF board and use wood screws to fasten them together.
- Apply a bead of silicone caulk to the inside joints of the mold where the side strips meet the MDF board and the corners.
- Run the silicone caulk with a wet finger to smoothen it and give it an even round shape. This will eventually form the chamfer on the edges of the countertop.
- Place a piece of foam of the same thickness as the countertop to cut space for the sink over the marked place on the MDF form. Glue the foam into place and use painter’s tape around the edges of the foam to stop the concrete mix from seeping in.
Reinforcement and Mold Preparation
To prepare the mold for concrete pouring:
- As the silicone caulk cures, cut the re-mesh into the dimensions of the countertop to fit it inside the mold. Allow a gap of two inches on all sides. This ensures that the re-mesh doesn’t extend to the entire length and width of the countertop.
- The inside of the mold will form the outer surfaces of the countertop. The bottom of the mold will be the top of the counter. Therefore, ensure the surface is smooth without imperfections to get a clean finish.
- Peel off any excess silicone caulk and sand the inside of the mold smooth with fine-grit sandpaper (if necessary).
- Finally, clean the inside surface with some rubbing alcohol.
Pouring the Concrete
You can use any high-strength cement to form the countertops. White cement with pigments can also be used to get the desired color. You could use a countertop mix if you want the best strength, finish, and surface properties. Here is how to work the concrete:
- Use a cement mixer to get the perfect mix and work fast before it begins to set.
- Pour the concrete out of the mixing tub into the mold and fill it about halfway in the mold. Use tools to work the cement uniformly into all sides of the mold to ensure no air bubbles are trapped in between.
- Level out the half-filled mold and lay down the reinforcement mesh on top of the wet cement, ensuring a gap of about two inches on all sides.
- Pour more cement over the mesh and fill up the mold. Use some back and forth motion to flatten the wet concrete. Use a flat piece of lumber to move up and down over the cement to give the final flat finish.
- Remove any excess cement that might have gotten into the screw heads to make it easier to release the countertop from the mold.
Removing Air Bubbles
Air bubbles/pockets can weaken the countertop and need to be tapped out before the concrete sets. Here is how to do it:
- Smooth the surface of the poured concrete with float.
- Use an orbital sander without the sandpaper to vibrate the mold. Move the sander under the MDF board forward and back and side to side. Repeat the same on the sides.
- You can also use a mallet to gently tap under the mold and release any air pockets stored within. Use the float to smoothen the surface again.
- Make a second pass with the sander to remove any more air bubbles left in the cement.
- As the concrete begins to set, make a smooth surface using a trowel. Although this surface will be the bottom, you can achieve a good degree of flatness, enough to rest it evenly over the base cabinets.
- Cover it with a plastic sheet loosely to stop it from drying out too quickly as it cures.
Removing the Mold
Give the cement about four to seven days to set before the mold is removed. Here is how to work the mold out:
- Unscrew the wooden screws that were holding the mold together.
- Using a hammer, gently tap a putty knife into the joint between the concrete and the MDF strips.
- Carefully pry the strips free from the concrete sides.
- Using the putty knife and hammer, free the sides of the mount base and insert shims to loosen it from the MDF board.
- Using some help from others, lift the slab and force the rest of the MDF board free from the countertop.
- Flip the countertop over and rest it on the sawhorses with its top pointing upwards.
- Tap the foam off of the slab to reveal the sink cut-out.
Finishing the Countertop
This activity involves some sanding and sealing of the concrete slab to turn it into a neat countertop:
- Use 80-grit sandpaper and the orbital sander and sand the whole surface of the countertop to reveal any air bubbles or pockets on the countertop surface.
- Mix a small and fine batch of the same cement and include the same proportion pigments to achieve the same color.
- Put your gloves on and apply a coat of fine cement over the surfaces to fill in any voids.
- Allow it to dry for a day or two.
- Using the same 80 grit sandpaper and orbital sander, give the countertop a thorough run. Wipe and clean with a damp cloth.
- Use 120 grit sandpaper and run another round all over the counter. For the final smoothening, use 220 grit paper for a refined and polished finish.
- Vacuum the countertop dry and wipe with a dry and damp cloth for a final round of cleaning before allowing it to dry.
- Pick a good concrete sealer that is graded for home use, especially inside the kitchen. It is better if the sealer is food-grade.
- Follow the instructions on the sealer packet and apply multiple layers of sealers with the recommended drying time in between. The sealers protect the porous concrete from stains and give it a smooth and glossy finish.
Pros of Concrete Countertops
Here are some reasons to choose concrete countertops:
- Durability: Concrete counters are highly durable as the strength of reinforced concrete far exceeds many other materials in the market.
- Customizations: The most important reason to choose concrete tops is the level of customization it allows you to have. You can choose any size or unique shapes for the edges or corners or make one that fits the contour of your kitchen.
- Styling: Concrete can be made to resemble granite, metals, or left to its natural grey color. You can also add decorative glass or stone aggregates to give it a personal touch.
- DIY: Concrete tops can be handmade if you want to save on labor costs. With a bit of skill in woodworking and working with cement, you can make a great countertop.
Cons of Concrete Countertops
Here are the things you need to be cautious about:
- Time-consuming: Concrete countertops take their own time to cure and dry multiple times. Rushing it will give poor results.
- Stains: Concrete can stain if the surface coating is not adequate to protect it. The counters need to be resealed now and then. The countertops can also scratch or crack if something heavy is dropped.
- Permanent: Concrete is permanent, and you can’t do much to change it once it is cast in place. While it can last for decades, removing it would mean a remodeling of the kitchen. The cabinets can take some damage in the process.
- Need for highly skilled professionals for the desired look: When made by an unskilled worker, the countertops can become defective with uneven surfaces and develop cracks. Some skill in working with concrete is required to get the countertop perfect the first time.
1. How Do I Clean and Maintain Concrete Countertops?
Concrete countertops that are correctly sealed are just as easy to clean as regular countertops. Here are the instructions to clean a concrete countertop:
- Depending on the type of sealer used, ensure the cleaning liquid you are using does not act as a solvent for the sealer.
- You can clean epoxy- and polyurethane-sealed concrete tops with water and soap. Avoid using solvents such as rubbing alcohol or acetone.
- Regularly wax the countertop to keep it waterproof and protect the sealer coat.
2. Can I Apply a Sealer?
Yes. Sealers are essential for concrete top to protect the porous surface of the cement from liquids that can stain the surface permanently. It also protects the surface from stagnant water damage and freeze/thaw cycles in the cold seasons.
If you have just cast your concrete top, the ideal time to wait is about 28 days to allow it to cure fully before applying a coat of sealer. The sealers can be applied once in a few years if you start noticing abrasions, cracks, or scratches.
It is also essential to understand that concrete sealers are susceptible to damage from high temperatures such as hot pots and pans. Therefore, make sure to use some form of heat protection, like trivets.
3. Does a Concrete Countertop Scratch?
Yes. Plain concrete and sealers applied to it can be scratched with steel knives as all sealer materials are less hard than steel. In general, most countertop sealers offer good resistance to scratching, but they can be scratched easily with sharp tools.
Scratches can act as staining points and need to be fixed as soon as possible. When a scratch is seen, prepare the surface for a second round of sealing as per the instructions on the packet and apply a fine coat of sealer to fill up the crack.
4. How Long Will Concrete Countertop Last?
Well-built countertops made out of high-strength concrete can last for decades, if not a lifetime. They maintain their functionality and aesthetic appeal over time and likely won’t need replacement. Because of their very high durability, they are also more environment-friendly and save you the hassle and expense of replacing worn-out surfaces.
Concrete countertops can be made to any shape and size that fits over your bottom cabinet. It takes a little bit of skill working with materials to create a high-quality countertop that will last for decades. Concrete countertops come with the advantage of customizability and low cost, especially if you like DIY projects.