Build Your Own Concrete Countertops – It’s Easier Than You Think
This is its own project all together, but when it goes on your island it will be most impressive! We will start similar to the foundation, not with digging, but with a form.
First Things First
Measure your island and be sure of the dimensions before you start. Because of the irregular shape of the stones on the sides I wanted a 2” overhang on all sides. This time instead of using 2 x 4’s for forms we are going to use melamine. The reason for this is it is much easier to remove, and the texture leaves the countertop with a relatively smooth surface.
Cut your pieces for the top of the countertop 1.5 inches wider, to accommodate for the installation of the side pieces. Cut strips for side pieces as thick as you want your countertop. Mine was about 2” thick.
Clamp the side pieces in place one at a time and predrill and countersink the screws. If you don’t countersink the screws, they will be in your way when it comes down to leveling off the concrete.
Once your form is all screwed together, remove any dirt or sawdust that is on the surface. This can be done with a lint free rag and rubbing alcohol. Compressed air also works well to remove sawdust, just be sure to wipe it down before you go to the next step.
Using clear or white silicone place a small bead ¼ inch or so, on all the seams and smooth them out with your finger. Be sure there is no excess, as that will leave a void in the finished product. Again, be sure the surface is clean and let the silicone set up for 24 hours before the next step.
There are two ways to go about making this countertop. One is to pour your concrete, let it cure, remove the form, flip it over, seal it and viola “instant” countertop! If this is the route you choose then you can skip down to the next section. If you want to stick with me, then read on. The other option is the same, except after you flip it over the top and sides get polished. This is the rout I chose. If you plan on polishing your project, it allows you to place objects and designs into your top!
Now is the time to unleash your creative side! For my project I needed to create 2 forms. One for the main surface for grilling, and one for people to sit at and enjoy the food and conversation. For the latter, I decided to place some broken glass and a “K” representing my last name. Now you don’t have to do as I do… I’m just giving an idea of what is possible.
To create the “K” I took one of the rocks and sliced it into ½ inch thick pieces on my wet saw. Then I cut the slices into strips to form the letter. Then I drew a circle on my form, and used white glue and covered the circle. I was thinking it would work the same way glitter works, on projects from preschool. I’m returning to my childhood here!
I placed my pieces of cut stone and pressed them into the center to form the letter. Then I took the broken red glass and sprinkled it all around within the circle. Allow the whole thing to dry overnight. Not sure if regular white glue is the best thing to use to hold it all in place, but it worked OK for me.
Mix It Up
It’s time to get our hands dirty once again. My choice in concrete was a high early strength concrete. There are other types of concrete on the market specifically for concrete countertops, but for price and convenience I choose a type that was readily available to me at my local Home Depot.
Mix the concrete thoroughly into a peanut butter like consistency, then shovel, or bucket it into your form. I started in the corners first, and made sure to pack it tightly. If you are going to put a design on your top, be sure not to disturb it too much when you place the concrete on top of it. It works OK if you pack it straight down, but try not to move it side to side.
Fill the form completely, then use a straight 2 x 4, or other straight edge level off the top, by moving it back and forth in a sawing motion. The same way it was done for the foundation.
To remove any voids and air pockets the whole thing needs to be vibrated. This allows the air to rise to the surface. Remember, your countertop is upside down, so any air will leave a void in the top. I’ve seen people use a rubber mallet to accomplish this, but it seemed like a lot of work, especially on a large countertop. My solution was to use my reciprocating saw without a blade on it. I held it directly under the form, and on the sides, and vibrated it like crazy. It’s amazing how much air gets trapped in the concrete during the pouring process. Do this until minimal air bubbles rise to the surface… yes, it takes a while.
Take A Break
The key to curing concrete is to not let it cure too quickly. I kept my counter covered with plastic for a week, spraying it with a hose daily to keep it moist. This helps to slow down the curing process, and to keep it from cracking. I poured my concrete into the form that I had resting right on the grill island. It took approximately 4 and ½, 80 lbs. bags weighing 360 lbs. total. That’s 163.3 kilograms for my friends outside the United States. This thing is too heavy for one man to move!
After it was cured for a minimum of one L O N G week it was time to remove the form and reveal my creation. Take care in removing the form. The concrete can still chip off the edges. Use a pry-bar against a piece of wood for the stubborn pieces, never use your pry-bar directly on the concrete.
This next part took some engineering for sure. The task was to flip this monster and then place it exactly where it had to be. This is where we go back to that famous nation… DETERMI-NATION. There were 5 people to help and a determined mind, so using leverage, the top was maneuvered onto a few 2 x 4’s and my picnic table. We then slid the top, with the form still under it and the sides removed onto the 2 x 4’s.
With the counter off the island I mixed up a batch of mortar and placed a bed all around the perimeter of the grill island. Then using all our might, we flipped the monstrosity over. Slowly and carefully we put it in position and laid it to rest. If you do this, remember communication is key when working with other people. The whole process is no way to lose a finger, or worse, just be careful!
I repeated this step again for the upper countertop. That’s the one with the broken glass in it. Being much smaller and lighter, it was easier to maneuver, and required fewer of my tired friends. In the next segment you can see the entire project completed.
As you can see, it’s not too difficult to build your own concrete countertops, and get a professional looking result. If all you were after is a solid place to slice, dice, and roll out your pizza dough, mission accomplished. Just seal the concrete and enjoy. If you are like me and just HAVE to go that one step further, go to the next post to see how it all comes together.