Basically, there are seven steps separating you from your very own concrete countertops:
- Measure
- Build the forms
- Reinforce
- Mix and pour
- Polish
- Slurry
- Seal/Finish
- Install
Step 1: Measure
Steps 1 and 2 are probably the trickiest, and also the easiest to screw up. If you measure incorrectly you'll end up with one big, heavy problem on your hands. So measure twice, cut once, etc. The simplest way to explain this is just to tell you to measure all four sides of the counter surface (i.e., the tops of the cabinets). Don't assume the wall is square. They're probably not. Measure all of the sides and write those measurements down, making sure to factor in a 1/2" overhang on the front and sides of the counter surface. There: you've measured. That's step 1.
Step 2: Build the forms
You'll be making these forms out of melamine. The most important thing to note is that you'll be pouring your countertops upside down. That makes building the forms an exercise in spatial and geometric thinking. You'll want to take your time here.
So you've got your measurements. The first cut you'll make is the bottom of your form, which is also the face of your countertop. This one's easy. All you have to do is cut the exact dimensions that you'll eventually want your countertop to be. Once you've made this cut lay it out on top of your cabinet(s) and make sure the measurements look good. Think of this as a mockup of your countertop. If it looks right, it's time to make the sides.
To make the sides of your form all you have to do is rip the melamine into 2 3/4" strips. Since the melamine is 3/4" thick, this will result in a 2" thick countertop. If you want it thicker, cut the strips wider. Now cut the sides to length and screw them into the bottom of your form. Your sheets of melamine should be 3/4" thick, so by screwing the sides in flush with the bottom you should basically have a 2" deep box. Make sense?
The next step is to caulk all the seams. Your form has to be water tight, OR ELSE. The easy way to do this is to use black caulk to make sure you don't miss anything. I tape off each side of seam with painter's tape to ensure the caulk line is straight and clean. Any mistake you make caulking will show up in the concrete. If your countertop has a sink in it, you'll want to make a knockout out of rigid foam insulation. The only trick here is finishing the sides of the knockout. This has to be water tight too. You can use packing tape and a little spray adhesive to get that done. OK - your form is built. Let's reinforce that sucker.
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waterproofing the sink knockout |
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Another angle of a finished form. |
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Step 3: Reinforce that sucker
This one's fairly easy. You'll need to lay rebar along the outside edge of the form, 2" away from the edge, and then lay remesh in the middle. These things cost a few bucks at Home Depot, but they can be tricky to mark and cut. What I do is measure the length, and mark with a piece of blue painter's tape. Then I clamp the rebar down and go wild on it with a sawzall. Are there better ways to cut rebar? Maybe. Do I care to research what they are? Apparently not.
So I've read a few of these Concrete Countertops bibles, and they usually have a chapter devoted to an elaborate system of wires that suspend the rebar just off the base of the form. In my experience, that's just not necessary at all. Just cut the rebar and remesh, make sure it fits in the form and set it aside for pour day.
Step 4: Pour Day
This is where it gets fun. First, rent a concrete mixer. Don't try to do this by hand. It is NOT worth it. Next, figure out how much pigment you want to include per bag of concrete that you use. For these counters, we used about 2 tbsp of pigment per bag of concrete. Some people like to make test batches to see what it will look like. Maybe that's worth it, but concrete is pretty unpredictable. So I've never bothered.
Time to mix. Pour 2 bags into the mixer and toss in your first batch of pigment. Then add a little water and turn the thing on. Incrementally add water until the concrete is a thick, soupy consistency. Think of a good, chunky oatmeal. Or, if you're unfortunate enough to be from Canada, think of a porridge. It's a good idea to measure exactly how much water you use the get the concrete to the right consistency, then duplicate that for every batch.

Once you like the consistency, turn the mixer off and let it sit for a minute or two. Then transfer the concrete to buckets, lug those heavy bastards over to the form and get to pouring. Nothing's quite so satisfying as pouring the first batch into that form. Pour some 'crete in and spread it around with a wooden float. You want the concrete to be about 1" thick around the entire form. Really work it into the corners with the float and with your hands. If you don't spend the time to work it into the corners, you're going to end up with honeycombing, which is something we'll get into later.

Once you're comfortable that you've worked it in as good as you can, grab your orbital sander. This is a little trick I came up with that's worked great for me. What you do is cover the sander in a thick piece of plastic (I use a torn up contractor's bag) and secure it tight with rubber bands. You want it to be as close to water tight as you can. Then turn it on and press it into the wet concrete, working it over the entire surface. What you're doing is vibrating the concrete, which forces out any air bubbles and leaves an incredibly smooth surface. The official concrete countertop manuals tell you to use these big, aggressive concrete vibrators. You don't need that. This works fine.
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Left unattended, Greeks will eventually find their way to sleeveless shirts and manual labor. |
Time to lay that Rebar in. Basically all you need to do is lay it over the vibrated concrete. Keep it at least 1" away from the edge of the form, and make sure it doesn't get within 1/2" of the top of the form (what will be the bottom of the countertop). Once that's done, go ahead and pour another layer of 'crete over the top. Float it until you think it's about right.

Time to screed. You'll just need a short, straight length of wood with a clean edge. I like to use a ripped down piece of melamine. Work it back and forth in a sawing motion while dragging it across the form. You should end up with a nice, flat, smooth surface. Now, grab that orbital sander again. This time you'll just turn it on and work it around the outside or the "face" of the form. You're just trying to settle all the concrete against the melamine as nicely as you can. Once you've done that, you're done pouring. All you need to do is float the concrete ever 10 - 15 minutes or so until it's firm. This helps make the bottom of your countertop nice and flat, which you'll appreciate when you go to install it.
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beautiful... |
Step 5: Polish
The first step here is to wait. After pouring you need to give the countertops between 20 - 28 days to cure. The concrete needs to be hard enough to polish, but not too hard to polish. So once you're done waiting, go ahead and carefully flip over your countertop. That's going to be an anxious moment, but it's worth the wait. Again you'll need your trusty orbital sander and some diamond polishing pads. I get the JX Shine Diamond Polishing Pads from Toolcity (just search "diamond polishing pads" on Amazon), and they've never let me down.
So get a bucket of clean water, a sponge, a squeege, your sander and pads.
The technique here is pretty simple. I usually start with the 800 grit pad, because I don't want to expose any aggregate (i.e., stone). Just wet down the concrete with the sponge and kick on the sander. It's very important that you have the sander plugged into a GFCI. They're cheap, and they'll keep you from electrocuting yourself to death. Polish in circles and take your time. Once you're satisfied wet the concrete down again, squeegee it off and switch to the next polishing pad (probably the 1000 or 1500). Repeat this process until you get to the Buff pad. You'll be able to see and, more importantly, feel the concrete getting smoother.
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This one's all polished up and drying. |
Step 6: Slurry
This step is boring, but important. Regardless of how well you vibrated you'll end up with some small holes in your counters. This is expected. You'll have to patch these. Slurry is jut portland cement (available at the Depot), pigment and a little water. Think of it as grout used to fill those little air bubbles. Mix the slurry as close to the color of the countertop as you can. It won't be perfect, but it doesn't have to be. These minute imperfections give the countertops character.
Step 7: Seal/Finish
Concrete countertops are great. They look incredible while costing little. The biggest complaint is that they stain. The fact is: concrete is porous, and it's designed to soak up moisture. So what do you think happens when you spill red wine on your countertop? It gets soaked right up. This is why the finishing and sealing of your countertops are possibly the most important part of the process.
We've used a few products, but Counter Hard seems to be the best. This product comes with instructions, so I won't bore you here. But to summarize, you heat up the counter to steam off the moisture that's trapped within. That dries out the concrete, meaning that any moisture that touches it will be drawn right in. So when you apply the sealant, it's soaked deep into the countertop. You repeat this process a couple of times and BOOM: your countertops are bulletproof (disclaimer: product does not actually make your countertops bulletproof).
Step 8: Install
Here's something you might not know: concrete is heavy. This is why I always install a layer of 1/2" plywood over the cabinets. It helps displace the weight and keep your cabinets in one piece. Other than that, just run some caulk on the plywood and place the stupid countertops down. It's easy. If you've got a sink knockout for an undermount sink (which looks really damn good), place the countertop down and trace the sink cutout before cutting that out with a jigsaw.
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great for placing delicious treats down |
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this is a sink |
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all told the countertops cost about $250 |
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this is a cat, in a sink |
So this is a basic rundown of how to get sweet new countertops on the cheap. It's a little daunting at first glance, but I'm no professional concrete worker and we successfully did both kitchens without permanent physical, or psychological damage. If anybody has feedback, additions, omissions, insults or obscure sports trivia I'd love to hear it.
What you'll need:
- some melamine (it's plywood, but covered in a thin plastic coating)
- 1 3/4" drywall screws
- caulk and painter's tape
- Quickrete 5000 (it's what your countertops will be made of)
- rebar/remesh
- pigment, if you want it
Also you'll need these tools:
- table saw
- drill, or a screwdriver and lots of patience
- hacksaw
- orbital sander
- caulk gun
- diamond polishing pads. not as expensive as it sounds
- concrete mixer (rent it)
- squeegee