The material we used for the frame was white laminated melamine boards. These boards provide a smooth non-porous surface to pour the concrete into. So we cut a board larger than we wanted the finish slab to be. Then stripped out side pieces, with a table saw for the frame of the slab. We decided on 1 1/2 inch thick countertops. So the stripes we cut 1 1/2 inch wide. We marked off the dimensions on the flat melamine board and screwed the strips to the board using wood screws. This formed a tray on the surface of the larger board. (sorry, I don't a photo of this)
Once the frame is built, you want to run a bead of chalking along all the corners inside the frame. Then remove any excess chalking so the corners are still square. I just used my finger to run along the chalking line and wiped off the excess chalking. This allowed me to feel that there was no large buildup of chalking in the corners. We also experimented with using 1/2 round shoe molding to form a beveled edge to the overhang. We decided it was worth adding the molding. We cut the molding to fit snuggly into the frame along the front and used the chalking to hold it in place. (note: if using the molding, do all the chalking after the molding is in place.) You also want to keep in mind that you are pouring the countertops upside down. Be sure the beveled edge is where it needs to be once the tops are flipped over.
You can see the beveled edge in the photo below.
Once the chalk is dry, you want to oil the inside of your tray with vegetable oil. You just want a very thin coating. We actually wiped off the excess with a paper towel. You don't want to seeing in pooling of the oil. (The oil is to allow the concrete to detach smoothly from the boards once it's dry). We placed our frame on two saw horses. Be sure once the frame is in place that it is level. You also, want to place sheets of plastic under the saw horses. The concrete will be spilling over the edges and falling to the floor.
Now it's time to mix your quikrete according to the directions. We only mixed enough to pour one slab at a time. So we just stirred the mixture by hand. We didn't use a mixer. You want the mixture to be completely wet and easy to pour into the mold, but not to soupy. Pour into the mold and begin to smooth the surface with a trowel. As you smooth the surface water will be rising to the top and pouring over the edges. You want to be sure that your frame is full to the top with concrete but not rising above your side boards. So just keep troweling over the surface until it looks smooth and water rising begins to slow down.
Then you want to vibrate the frame. We just used a rubber mallet and gently tapped all around the frame and underneath the frame. As you do this you will see bubbles rise to the surface. You want to continue tapping until you are seeing very few bubbles coming up. You also want to smooth with the trowel several times during this process. Once the bubbles are becoming less and less and the surface is fairly smooth, you want to leave it to sit for at least 3-4 days.
Once the concrete has dried completely, you can remove the screws holding side pieces. Gently remove the side pieces and turn your slab over. Hopefully, you have a smooth concrete surface.
We did have to re-pour one piece of our countertops. The piece had a lot of larger pits and I knew I wouldn't be happy with it. So we poured another one and it was great. This error only cost us a few more dollars! There are machines that you can purchase or rent that do the vibrating for you. If you are pouring larger sections, it may be worth using the machine. Our longest section was 52" long.
Also, keep in mind they are going to be heavy. The 52" long section was to heavy for my husband and I to lift. Thankfully our builder was on site to help him.
We also experimented with putting dye in the concrete mix to give it color and also staining the concrete after if was dried. All of these techniques worked, however in the end I preferred the natural color of the concrete. We were able to use a concrete chalk to seal the seams and attach to the cabinets and it was a flawless look.
This photo shows the concrete chalk line where we joined the two pieces together.
Once the countertops were installed, I used a water based sealer from my faux finishing days to seal the surface and keep stains from attaching to the countertops. This was my most expensive purchase for the countertops. I knew it would hold up well against water and around the stove top. I applied the sealer with a sponge roller and applied in very thin coats. I sealed 3 times over a period of 3 weeks. I didn't want the sealer to build up to quickly, because I had heard that the sealer sometimes wants to peel off the concrete. By allowing an extended drying time, we have not had that problem.
Here is a list of our materials. Everything was purchased at Lowes Home Improvement except the sealer.
White Laminated Melamine Board 8'x4' cut to sizes needed
concrete colored chalking for sealing & connecting edges once installed
vegetable oil (any brand will do-purchased grocery store)
medium metal trowel
plastic or something to protect your floors
food safe sealer - I used C-500 Urethane Satin from Faux Effects, Inc.
If you have any questions, PLEASE DO NOT LEAVE A COMMENT ON THIS BLOG. Please connect with me through Instagram and I'll be happy to reply.
I'm sure there are other more professional tips about how to build your own countertops, however, it worked for us and saved us a lot of money. We are very happy with how they look. We've been in the house for over 6 months and they are holding up great.