In Part 1 of this two-part series, we shared about the prep work needed for your DIY Concrete Countertops. Now we are sharing about the exciting part: pouring and installation!
Good News! The prep was the hardest part, now let’s get to pouring …
DIY Concrete Countertops Part 2
Pouring Your DIY Concrete Countertops
We are going to break pouring your counters into a few phases. Each phase is as important as the last, so be prepared to take 3-4 hours to get it right. After all, these will be the centerpiece of the kitchen.
You will first want to set up the molds on a flat surface, making sure to use a level and shims to get it totally level. We had a large concrete patio available to us, so we chose to do it there. But if you don’t, you can set it up on some sturdy sawhorses or any other flat surface. This will ensure consistency in thickness.
Next, you will again want to wipe out any dirt or dust with alcohol. This will make sure your surface is smooth.
Last, you will take mineral oil (cutting board oil) and coat the surface of the melamine with it to ensure the concrete does not stick once dry.
2. Mixing the Concrete
You should have your concrete mixer set up. Have a good water supply, trowel, and wheelbarrow ready as well. You will want to put on a good dust mask for this portion, as concrete is dangerous to breathe in.
Grab your concrete and fiberglass fibers. There is no exact science to this, but we decided to do about one good-sized handful per bag. Start by putting the recommended amount of concrete in the mixer, as prescribed by the manufacturer (typically one to three 80lb bags for a rental machine), and the appropriate amount of fibers. Turn the mixer on and begin to add water slowly.
You don’t want the concrete to become too wet, as this can weaken it. As it is churning, add water until it turns to roughly the consistency of peanut butter.
Once your concrete is ready, dump it into a wheelbarrow or buckets and begin pouring it into the molds as quickly and safely as possible. Again, it is always helpful to have a friend. Once your concrete is in the mold you will begin to screed, or use your trowel to apply pressure across the surface of the concrete to smooth and remove any excess water from the concrete. This will help prevent weak spots. You will especially want to make sure to press on all edges so that the concrete fills the mold for your DIY concrete countertops entirely.
4. Removing air
The final step will be to make sure there are no air bubbles in the concrete. To do this you will take your orbital palm sander and run it along the edges of the molds for as long as water and air are coming to the surface. Use your trowel to remove the water and repeat. Once it seems like the air and excess water is removed, the waiting begins. Concrete technically takes about 30 days to cure fully. You will want to wait roughly two weeks at least.
While the concrete is curing, you will want to keep it covered with plastic or a tarp. Every day or two, you will want to hose it down. This will slow the drying process, which strengthens the counters … because of science.
Finishing, Installation & Concrete Countertop Care
After about a week of curing, you can begin the finishing process for you DIY concrete countertops.
Smooth & Sand
The first portion of the process will be to remove any raised portion of concrete from the back so the counters sit properly on the cabinets. To do this, you will take your angle grinder with a diamond concrete grinding wheel and begin to knock back any obstructions. We also chose to smooth out all the overhangs so that it was smooth to the touch.
After two weeks, we flipped our counters over. To do this, you take a hammer and lightly tap the rail that extends past the corner. Now grab your friend. You will want to stand the counters up on their edge that will be touching the wall by lifting the melamine. Carefully peel away the melamine. It might take a little tweaking to break the seal of the caulk. Once it is free, move the melamine to the bottom side of the counters and slowly set it down. Take a good look at the surface of the counters. They look pretty nice, eh!
Once your counters are secured again, you are going to take a palm sander loaded with a 60 grit sandpaper and begin running it across the surface. This will begin to open up any air pockets on the surface of the concrete.
Once you have thoroughly sanded the surface, take some of your portland cement, mixed to manufacturer consistency, and work it into any of the openings. The only thing I would do differently here would be to add a bonding agent to the cement, as I had to do it a few more times to get everything to adhere properly. After the prescribed drying period, sand with 220 grit sandpaper. If more pockets open up, repeat the previous step until counters are smooth. Now is a good time to sweep or blow off the surface of the counters, so as not to drag any concrete dust into the house. It is no fun to try to remove.
Installation of Your DIY Concrete Countertops
Now, we are ready to install the counters. Making sure to carry them on end, begin to set the counters into their intended location. If one is not sitting flush against the wall, simply remove the drywall where it is stuck to create more room. You will want them totally flush against the wall. Once you are happy with how they are sitting against the wall, take a level and begin to make sure the counters are level on the cabinets. Where needed, shim the counters to compensate.
The last piece you will set will be your sink rails. Once the adjoining sides are in place, apply a good amount of a two-part concrete adhesive to the butt ends of the rails and their adjoining sides. Set them up so they are level and clamp them into place. It will typically take at least 24 hours or more. We had to do it twice because, after 24 hours, the glue had not hardened. After 48, it was harder than the concrete, so be patient.
Now take a color match caulk or clear silicone and run it around the bottom edge where the counters meet the cabinets. This will ensure they do not move over time.
Finishing Methods & Maintenance
There are quite a few different options for finishing these DIY concrete countertops, and what you pick simply depends on your intent. For us, we wanted them to be matte, to maintain the industrial quality, but you can go all the way up to a high gloss. We also wanted a finish that was rated for food. The downside of this is it requires a little more maintenance, but it seemed worth it for the peace of mind.
There are two kinds of finishes available. One will create a lacquer-like finish on the surface of the counters. The other will saturate the counters ensuring they do not soak anything up. This is what we went with. The instructions were simple: Start with a diluted mixture and work your way up to a pure mixture, allowing the compound to saturate the surface of the concrete. The final stage creates a hardened surface. The manufacturer recommended doing it once a year.
DIY Concrete Countertop Review After a Year
After a year of use, the counters are great. They are easy to wipe down and are very durable. I was quite nervous about them breaking, as my wife and friends have a propensity to sit on counters. But they were extremely strong. We did have a few smaller air pockets open up that we filled with concrete adhesive and porter cement. This is why I recommend using an adhesive when initially filling the air pockets.
Overall, if you have the time, curiosity, and space, I recommend taking on this project.
What did you find most helpful about this DIY concrete countertops tutorial? Do you have any questions that we didn’t answer in this post? Let us know in a comment below!