How to make concrete countertops

How to make concrete countertops

Are you considering replacing your old kitchen countertops? You’ve been browsing different options but haven’t found anything that feels right.

You may enjoy doing things yourself or want something truly unique. In this article, I will show you how to make concrete countertops independently.

Poured concrete is a trendy choice for countertops these days. You might assume it would look cold and industrial, more like a workspace in a garage than a kitchen countertop.

However, this is different. Concrete countertops can be finished to be as smooth as glass and just as glossy as granite. They can be stained, colored, textured, patterned, or left plain.

If you’re familiar with this blog, polishing, staining, or stamping concrete floors is no different from making concrete countertops. You can achieve great results that can rival any commercial options. Buying pre-made concrete countertops may be more expensive due to the added labor cost.

How to make concrete countertops in place

Poured countertops can be a DIY project, but it is relatively high on the difficulty scale. It can be done, though, and I’ll explain how you can successfully pour concrete counters yourself. I will provide a simple outline of what needs to be done, and you can decide if it’s something you want to try.

Making the base of the form for concrete countertop

First, you need to remove all old countertop material and discard them. You will need to shore up the top of the countertop using plywood. You’re making a form for the concrete here, so you want it to be well attached to the kitchen cabinets beneath.

Cover the plywood with tarpaper to prevent the concrete from seeping into the plywood. If you don’t have a tarpaper, you can do it without.

Remember, the concrete will stick to the plywood, and it might need some muscle to remove it someday. One way to avoid this is using form oil or cooking oil on the plywood so it won’t stick to it so much.

The plywood might need to come out so you can attach the edge support under it. It has to be under the plywood so your concrete table edge will cover the plywood from the side when you look at it. You want to avoid seeing concrete on top of plywood, as it’s just plain ugly.

Attach the edge to the concrete countertop form.

There are two ways to do this: bottom plywood stays, or bottom you remove it after the concrete is curing/hardening.

Purchase Styrofoam for forming the edges or some other material like it. If you’re okay with straight edges, even plywood will do OK here. Styrofoam gives us something easy to shape.

  1. Bottom plywood stays

Shape the inside of the Styrofoam in the shape you would like your countertop’s outer edges to have. You are using the appropriate tools to ensure evenness. Place the Styrofoam against the countertop edges. Place a 1″ x 2″ strip of wood along the outside edge of the Styrofoam.

Now, you have the outer edge of your form done. We need to attach it so the plywood won’t show from the side. This might be achieved by attaching a plywood slide under the counter plywood we installed to come a little over the cabinet edge. 1″ should be enough for there to be enough concrete that it won’t crack.

Now nail or screw through the wood and the foam into the plywood under the countertop. This will provide the outside for the concrete that hides the underside plywood.

You can use the wood alone to form around the hole for the sink. Also, the sides and back can be done with plain plywood and removed after the concrete has cured for some time.

B: All the plywood will be removed

This way, your bottom plywood has to be the exact size of the countertop, and the edges can be done like above. Depending on the countertop size, it can be done like this: Remember, the weight will add very fast with a bigger pour, and it won’t be a solo operation to remove the bottom plywood.

I suggest leaving the bottom plywood in place. It will also make a thick-looking countertop weightless.

Adding the rebar for the concrete countertop

Using rebar, placed from front, back, side to side in a grid-like pattern from board to board. This will form a skeleton, provide strength, and help prevent cracks in your concrete. The rebar has to be lifted a little from the bottom form so the concrete can get under it; this way, it will provide the needed strength.

Use cooking oil as concrete form oil substitute

Pouring concrete countertop

Mix your concrete according to the instructions. It will be the correct consistency when you can form a ball that does not droop or crumble in your hand, holding its shape. When you have achieved the proper consistency, pour or shovel the concrete into the frame you have prepared.

Depending on the rebar, the height from the bottom plywood and the total thickness of the countertop might be the hardest part. Again, spraying the form with some oil and wetting the surface before adding the concrete will make removing the forms more accessible.

Once the concrete is in the frame, we must give the form bottom little hits with a hammer. This will help air escape from under the concrete and be denser and better around the rebar. You will notice from the surface of the concrete that it will level a bit when you hammer the bottom.

Then, you screed it level, adding or removing concrete as necessary. Suppose you’re still getting familiar with the term. In that case, you take a level tool as comprehensive as your frame and move it back and forth so the extra concrete on top of the frame moves towards the end that has yet to be concrete.

Work quickly, though; concrete begins to dry in about an hour. The heavy aggregates will settle to the bottom, and the slurry will move to the top, giving you a smooth finish.

If you are using color, it is time to sprinkle the color evenly over the concrete. Make sure you cover every inch and try to get it all even. Using the trowel, continue smoothing the concrete. This will force the color into the concrete and prepare a smooth surface on the concrete.

Another way to add pigment is during the mixing of the concrete. This will need some testing before you make anything to get it right. Pigments should be available in hardware stores and on the Internet. You can also search for other things people might put into their concrete. Like troweling of pigment, you could add something to give a little sparkle.

When the concrete is curing, you might sparkle some water so it won’t crack so much on the surface. You don’t want to pour water on it; spray that gets the surface. A little moisture is enough. You can repeat this every few hours; it will make the concrete harder as it cures.

Time to finish and coat your concrete countertop

When the concrete has hardened, remove the frames. Mix colored powder into a grout-like mixture of concrete and spread this along the edges of the countertop to add color to the bullnose portion of the countertop and fill the possible air bubbles from the edge; this will give it a smoother look when we use a coating.

When the frames are off, it’s time for the finishing touch. The concrete, at this point, is still rough. We could polish it smooth and then stain it or use a pigment coating to make patterns with stencils. The options are limitless.

When the coating has been done, the surface of the concrete is waterproof and ready for whatever purpose you might come up with. As I said, DIY concrete countertops can rival any other sold-ready countertop, which is truly unique.

Conclusion

Before you start making concrete countertops, it’s essential to keep a few things in mind. Firstly, if you’re working alone, consider making the countertops in place, as they can be challenging to move depending on their size.

In case you cannot do so, seeking some lifting help is recommended to make the process easier.

While making concrete countertops, there are two main challenges that you might face – air pockets and forming them on the spot. The edges of the form can be particularly tricky to get right.

To avoid air pockets, you must be patient and knock out any trapped air. Additionally, it’s essential to ensure that the edges of the form are well-made, as this can make all the difference in the final product.