Learning how to make concrete countertops is not that difficult. Proper planning and good design is key. I always visualize the entire process, step by step, before I take my first measurements.
Concrete Countertops | Step by Step
First, draw a sketch of what you have in mind for your countertop. Explore all of the design options concrete countertops has to offer. Determine what other materials (if any) you will incorporate and understand the methods of adding integral drains, decorative inserts and other opportunities to get creative.
Inspect the structural integrity of your cabinets to ensure they will hold the weight of concrete
Remove your existing countertop and prepare it for your new one by fastening plywood to the top of your cabinets. This will distribute the weight of the concrete and also give you a surface to use while you build your new concrete countertops.
Make your template. If you have an existing wall that is out of square or bowed taking measurements with a tape measure and writing them down leaves room for error. By making a template, it will ensure accuracy and make life a lot easier for you.
Build your Mold
When you’re learning how to make concrete countertops this is the part where patients and good design play a big role. Your mold is the negative image of what your countertops will be. Concrete molds can be a work of art in themselves. It breaks my heart sometimes to tear them apart after I’ve completed the pour. Here are the most important things to remember when building the mold:
Melamine is what I typically use. It is a 3/4 inch plywood with a smooth veneer on both sides. The concrete will form and take on the mold’s texture to the finest detail. So if you use a smooth surface for your mold, your concrete will have a smooth surface. If your mold has a rough surface, your concrete will have a rough surface, which is fine as long as that is the look you are going for.
Your mold has to be water tight. Concrete dehydrates as it cures, this is how it goes from a liquid material to a hard surface. We want our water to escape from the top of the mold evenly, but if your mold is not sealed water will escape were ever it can leaving a discoloration in your countertop. Making your mold water tight can simply be done with applying silicone calk at the seams, this will also round your corners for you so it’s a win win.
Use your template to make your mold. We already talked about the importance of accuracy, and besides, that’s why we made it in the first place. Simply put your template down on your melamine and form the side to it.
The bottom of your mold is the top of your concrete. So remember when you are looking at your mold you are looking at the negative image of your countertop.
Mixing the Concrete
Mixing the concrete. There is nothing wrong with buying a premixed countertop mix. There are many, very good products available. Or we can mix it from scratch. Whichever route you decide to take concrete needs a certain amount of water to properly hydrate. The water you use beyond that will weaken your concrete. If you buy a premixed countertop mix do your homework and pay attention to the water amount you put in. If you mix it from scratch, Pay attention when adding the water.
After cleaning with a shop-vac or wiping your mold clean you are ready to pour. If you have placed decorative inserts be careful during the pour, use your hands and gently place the concrete into the mold if you need to, this will ensure that you do not dislodge anything that is glued into place. Use a vibrator or gently beat on the bottom of the mold with a rubber mallet, this will work all of the air bubbles out from the face. Then simply float to the top of your edge forms, which should be cut at the thickness of your countertop. Cover with plastic and let it set up.
Strip and Polish
Gently pull the forms and, with the help of a friend or two or three, flip your countertop over. Using diamond polishing pads and a variable speed grinder start polishing. It’s just like sanding wood with sandpaper. You start with 50 grit, then 100 then 200,400,800,1500 they even have 3000 grit. By that time you should be able to see yourself.
Sealing your countertop will protect what you have worked your butt off for. Remember that sealing your countertop is not the same as sealing your driveway. You must pick a sealer that is safe enough to eat off.
Installing your countertop can sometimes be a chore. By planning this step out before you get started you can determine how to break it up into manageable sections when you install. If you think it will be too difficult to install, you have the option to pour the countertop in place instead. Pouring a countertop in place can be a messy task. Consider this before you make you decision. After you have dry fit the pieces into place to ensure a good fit, raise the pieces up, one at a time, and spread adhesive on the plywood the countertop will set on as well as to each other. Once this is done to all of the sections you can use clamps to keep everything secure while the adhesive sets up.