This is the tale of my adventures pouring a concrete counter top. Given the length it came to, I somewhat arbitrarily broke it up in 3 parts. Here in part 1, I’ll just go over some terms and background; in part 2 I’ll cover some details on forms and the actual concrete pour, and in part 3 go over the staining and sealing. Disclaimer – I am not an expert. I don’t do this for a living. Everything here was learn as you go and I make no claims as to whether any of it is correct, let alone the best way to do any one thing. Caveat emptor.

Concrete counter tops can be beautiful and come at a fraction of the cost of higher end counter tops. By way of quantifying that last item, the pour I’ll describe here cost me roughly $300 for material, including polishing pads but neglecting more ‘durable’ goods, e.g. powered grinder/polisher, and various floats and trowels. This is in contrast to, depending on the exact granite selected, something like $2000 installed for this size of countertop. Let’s ignore the labor; and since I enjoy the creative process, it’s not really time lost.

So before proceeding, you have to decide what type of pour you are going to do: Cast-in-place (CIP) vs pre-cast (PC). CIP is, as the name suggests the assembly of the form, pouring, and finishing the counter top at its final location. PC is built, poured, and finished “off-site” and moved into place after it’s completed. Each has its pros and cons.

The main difference in the pours is of course where you build the counter top; in addition, PC is the lager of concrete counter tops and CIP the ale. A PC counter top is (generally) poured upside down with the final counter top being at the bottom of the form whereas a CIP is poured “face-up” – your finished surface is visible from the start of the process.

A CIP pour has the advantage of there being no need to move the counter top after the process is complete. That can be a major advantage for large pours or more complicated shapes. Except for a very small pieces, a PC pour is just not in the cards for a 1-2 person job and if you have a large angled piece, moving it without damage is a challenge. I don’t think I’d DIY a large PC pour. Of course the disadvantage is that you are going to make a somewhat of a mess; careful preparation can mitigate that, but you will inevitably have a lot of clean-up to do. In addition, since the pour is in place, you will remove that area from use during the build – for something like a kitchen where you use it day in and day out, that can be a significant issue.

A PC pour has the advantage that all the mess can be restricted to a place where a mess is less of an issue – garage, back-yard, warehouse, etc. Additionally, you don’t put the area you are installing it to out of circulation during the build. Since the final surface is usually face down, you don’t see it during the build. This can be a pro or a con – on the pro side, you can get a close to finished surface if you prep the bottom of your form (top of the counter) well and pour carefully. On the con side, you won’t see any issues until the concrete is set and you flip your project. Of course I don’t see any reason you couldn’t do a PC face-up, but it seems that in most cases it’s done face down. I’ve also found that you can get a pretty nice finish just from the pour and troweling in a CIP, so on this front, there’s probably little difference. On the other hand, with PC, you better have lots of help, and be very careful, and be able to get around corners etc, or there’s a decent chance you will ruin your work (or PC in pieces and ‘merge’ them place).

I prefer the CIP and this is a CIP build and all the following is specific to a CIP pour – some steps and materials may not be necessary for a PC and vice versa. In either case, I strongly suggest that you do a test pour before proceeding to you project. This applies to both pour methods. This is my fourth pour: utility sink in the garage (PC), vanity for the bathroom (CIP, but poured outside, vanity moved after the fact), small utility cabinet (CIP, but poured outside, cabinet moved after), and this job (CIP). For each one, I still did a small test pour. It can be as simple as just pouring a 2×2 slab and going through the full process to make sure you can get the result you are looking for and that you like it. For this pour, I did a small garden bench.

Equipment

To tackle this project, you’ll need some equipment:

  • Cabinet/base – we’ll assume you already have those and won’t trouble you with the details for this build.
  • Cement board substrate – This goes down on the counter tops before you pour the concrete.
  • Concrete – This is self explanatory. Some detail below (but probably best to avoid any rapid set!)
  • Edge form (contain concrete, removed after is sets)
  • Mesh/rebar – Re-enforce/strengthen the concrete and minimize chance of cracking in the final product.
  • Polishers – Bring the countertop surface to your final desired smoothness. This can be done by hand or with a powered polisher and can be done wet or dry. I used all combinations.
  • Stain and sealers – If you want the finish color to be whatever your concrete color is (e.g. you can add dies directly at mix time – I did this on my PC pour and didn’t care for the result), you don’t need the stain. You will want to seal the counter top though since concrete is a porous material and will absorb whatever you put on it. I had both from previous projects – if, as is likely, you don’t, add $150 to the cost quoted above
  • Misc – plastic (to cover things), rollers, paint pans, small quart measuring ‘pails’, lots of tape – I’m partial to the 3M No Residue Duct Tape

Here’s my base prior to any prep for the pour.

Preparation

Given the base cabinets, the first step is to place base layer. I used Hardie Backer. In my case, given the large span over the beer fridge, I put down 1/2″ MDF. This raised the counter top surface and resulted in more exposure of an unfinished surface below the form (see “Form” section). In retrospect, should have put steel braces in instead of the MDF – 1/2″ changes feel of the height more than one would think and there was additional work to cover the exposed edge. Don’t (or do) screw the concrete board down to the cabinets. I initially did, but removed the screws and filled the holes with caulk. If you ever want to tear out the counter top, it’s going to be much harder to do that if you’ve screwed your base down into the cabinets. I just tacked it down with some caulk – the weight of the top should be plenty to hold it in place, and now I can just pull the whole counter top up/break it up without damaging the cabinets should I ever want to do something different.

HardieBacker substrate installed. On the right, you can see the screw holes I initially put in. I removed them an filled with caulk. The gap between the two pieces of cement board were also caulked as was the gap against the wall.

In the next Episode, we’ll talk about building the concrete form and pouring the concrete.