How to make concrete countertops

How to make concrete countertops

It might be time to replace your old kitchen countertops. You’re browsing different options, but none of those feel right for you. Maybe you like doing things yourself or want something truly unique. Here, I’ll show you how to make concrete countertops by yourself.

A new, and very popular, countertop choice is poured concrete. You might think that it would be cold and industrial, looking more like a garage workspace than a kitchen countertop. If you think so, you’re wrong. There are concrete countertops that will give granite a run for its money. Poured concrete can be finish as smooth as glass and just as glossy. It can be stained, colored and textured, patterned or plain.

If you’re a reader of this blog, the concept isn’t any different from polishing, staining, or stamping concrete floors. It’s exactly the same and it can bring great results that don’t lose to any commercial options. We could even say that buying them would be even more expensive as we need to count on the labor.

How to make concrete countertops in place

Poured countertops can be a DIY project, but is fairly high on the difficulty scale. It can be done though and I’ll explain how you can have success pouring concrete counters yourself. I will provide a simple outline of what needs to be done, and you can make a decision with that if it’s something you want to try yourself.

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

The plywood might need to come out a little 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 don’t want to see concrete on top of plywood as it’s just plain ugly.

Attach edge to the concrete countertop form

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

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

A. Bottom plywood stays

Shape the inside of the Styrofoam in the shape that you would like the outer edges of your countertop to have. 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. Now we need to attach it so that the plywood won’t show from the side. This might be achieved by attaching a plywood slide under the counter plywood that we have 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 can be 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 size of the countertop it can be done like this, just remember the weight will add very fast with bigger pour and it won’t be solo operation to remove the bottom plywood.

I’d rather leave the bottom plywood in place if possible. It will also make thick looking countertop weight less if that makes any sense.

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 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, it’s the height from the bottom plywood, and the total thickness of the countertop, this might be the hardest part. Again spraying the form with some sort of oil, wetting the surface before adding the concrete will make removing the forms easier.

Once the concrete is in the frame, we need to give the form bottom little hits with a hammer if possible. This will help air escape from under concrete and it will 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. If you’re unfamiliar with the term, you take a level tool that’s as wide as your frame and move it back and forth so the extra concrete on top of the frame moves towards the end that has no concrete yet.

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 as well as preparing 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 be putting into their concrete. Like troweling of pigment, you could add something to give little sparkle maybe.

When the concrete is curing, you might sparkle some water on it so it won’t crack so much on the surface. You don’t want to pour water on it, just spray that gets the surface 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 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 might want to polish it smooth and then maybe stain it or use a coating that has pigment in it to do patterns with stencils. The options are limitless really.

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

Conclusion

You should have some idea how to make concrete countertops now. Before you start you should really think about how to make concrete countertops in place as if you’re working alone they can be hard to move, depending on size.

It’s advisable to get some lifting help if doing them on spot doesn’t work. The problems with concrete countertops I can think of are air pockets and doing the forming on spot. Having the edges of the form done properly can be a little tricky. Air you just have to knock out patiently.

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