Please note: Learning how to make concrete countertops is a big one. If you've never mixed and poured concrete before, then you should not try this one because making a countertop is an advanced concrete project.
That being reality, if you have substantial concrete experience, solid DIY skills, and the tools and materials, give it a shot if you feel you have what it takes after reading this page.
No matter your concrete aptitude, this one is a two-person job because of all the heavy and awkward lifting involved.
Ok, no more cautionary notes... ...Let's get started.
Your First DIY Concrete Countertop
You might know first-hand that working with concrete can be backbreaking work; plus, the creation of anything made of concrete takes time, not only to build it, but also to let it cure properly.
As a result, it is best for your first DIY concrete countertop to be small, such as a small outdoor "island" for a barbecue area, and it should be simple and require minimal finishing and coloring.
There are many reasons why concrete kitchen countertops are gaining popularity, but the primary reason is because if they are well-crafted, they are a unique and amazing-looking kitchen eye-catcher and conversation piece.
Plus, they are wonderfully functional...
...concrete countertops can incorporate kitchen features like back splashes, butcher blocks, and sinks, and they can be created in a huge range of colors, designs, and textures.
Concrete countertops are made with fiber reinforcement, acrylic, and silica fume pozzolan.
Pozzolan is a material which is combined with calcium hydroxide to create a substance with cement-like qualities.
Silica fume is a byproduct of silicon metal production and it happens to make a really good pozzolan.
Silica fume pozzolan adds strength and durability to concrete.
- Beeswax is a decent sealer for a bathroom vanity; less so for a kitchen countertop
- Pure tung oil can be used as a sealer
- Wet grinding and polishing is recommended or you'll be cleaning up dust for weeks afterward
- Make sure the countertop cures for 28 days before wet grinding
- If you want a matte finish, you can stop with 800 grit diamond sanding pads
- The shinier you want your concrete countertop, the higher grit you should work up to, up to 3000 grit.
- A mold made of melamine will release the countertop easier than wood, without a releasing agent - however, Melamine is more expensive
A number of tools and supplies are needed for making a concrete countertop. Here is a partial list:
Concrete countertop molds
Concrete countertop mix
Electric Concrete Mixer
Knockouts for sinks and other integrated features
To appreciate the process of how to make concrete countertops correctly requires you to have a thorough understanding of properly mixing and reinforcing concrete to prevent cracks from developing.
To truly know how to make concrete countertops effectively, a good understanding of countertop sealers is also essential.
Many concrete countertop pros mix their own custom sealer combinations to get the best results. This is a skill they've likely learned through experience, by trial and error.
Some concrete countertop makers use a polisher to grind the cement to a smooth surface.
Skilled makers of countertops will grind the skin from the concrete surface by using fine diamond polishing stones to maximize durability and appearance.
After curing and polishing, countertops are sealed. Different people use different techniques for this.
Epoxy Sealers have a good reputation, but take a week to apply properly.
Clearly there is a lot to learn when it comes to building custom concrete countertops, and fortunately there are classes offered in the U.S. and Canada where you can learn more about the process of making concrete countertops.
It would definitely be a good idea to do tons of research on how to make concrete countertops first, before tackling your project.
The first step when deciding how to make concrete countertops is planning.
You do not want to finish a countertop and then have to maneuver it around tight corners or over long distance.
Each foot of countertop space can weigh 20 lbs depending on thickness.
Your workspace must be well-ventilated and there must be plenty of room.
A final very important preparatory step is to make sure that the cabinetry under the countertop is going support the weight of the concrete countertop.
Make Countertop Template
Acquire a sheet of wood veneer, sized depending upon how big the countertop will be. You'll also need a glue gun and glue sticks.
Onto the sheet of wood veneer, trace the base of the countertop.
It is important to note that you're tracing the base of the countertop - in other words the dimensions of the cabinetry that the counter top will rest upon.
Overhangs for a typical countertop are 0.5 to 0.75 inches.
Next, you'll mark the template with control joints.
Let's say your concrete counter is 10' in length. The distance between the control joints should never exceed four feet.
If we divide the 10-foot section into thirds, and place the control joints at 1/3 of the length and 2/3 of the length, we'll place them at 40" (3'4") and 80" (6'8").
These joints are less than four feet apart, so they should work fine.
Obviously, the longer the countertop, the more control joints there will be.
Control joints are a way for you to influence where concrete cracks. Control joints allow for movement due to temperature changes and shrinkage as the concrete dries.
In general, space the control joints in feet no more than two to three times the slab thickness in inches.
If your slab is 3 inches thick, control joints should be placed 6 to 8 feet apart.
Control joints are cut to 25% of the depth of the slab. So for a 3 inch thick slab, control joints should be 0.75 inches deep.
Precisely when you cut these control joints has to do with the curing of the concrete and the weather and other atmospheric conditions.
Build Countertop Frame
The next step is to build the frame for your DIY concrete countertop using poplar or pine 1 x 3s held together with screws.
Use a 0.75 inch medium density fiber board for the bottom of the frame.
Attach this with deck screws too. Seal inside edges and corners with caulk to give the countertop slightly rounded edges.
Coat the inside of the frame with paste wax. Make a rebar grid with intersections approximately every 4 inches and secure the intersections with plastic zip ties.
Suspend the grid by placing two pieces of 1 x 2s or scrap across the frame and suspend the rebar halfway up from the bottom of the frame from them using wire.