DIY Cement Block Coffee Table
The goal: Create a large 48"x48" block style concrete coffee table, but not weighing 1000lbs of solid concrete, and also not be expensive. I searched around online and watched a handful of tutorials where people made concrete tabletops, and figured I could apply the same method to the top AND sides to create the solid block look. I documented what I did below, and what worked for us.
Here's an overview of the tools list, first:
4'x8' MDF panels
sealer (not sure I'd recommend the one I used; I'll explain later)
So here we go
I started by building the frame for our table. I used only 2x4's and secured them to one another using a kreg jig and screws. In the images below, you can see the structure of the frame I built. If you're unfamiliar with building in general, I highly recommend perusing through www.ana-white.com. She does amazing tutorials for wood building projects.
I built the frame to our desired dimensions 48x48. (The biggest bonus of DIY: making exactly what you need!) The frame needs to be slightly less than 48" to have a final width of 48" because the panels will add extra width! I made a mistake on that one, and we ended up having to add an additional small strip of MDF on the top panel, since our frame was slightly wider than the 48" panel width.
After we built the frame, we cut MDF panels to fit the sides and secured them on using a nail gun. Since the top panel is large, we made sure to add support beam across the top when we built the frame. Concrete can crack, so we wanted to make sure the top had extra support to never crack under weight of something on it. Once all of the panels were on, we used wood filler to fill in all seams and nail holes, and sanded it smooth.
Step 2: Ready for concrete. I used a bucket and paint stick to mix half the bag of concrete. A tip when working with concrete: once you start YOU CANNOT STOP, this stuff sets up fast. I mixed it with water to an 'easily spreadable peanut butter' consistency and started troweling. I spread it on in a layer about 1/8"-1/4" thick. Enough to cover and be able to sand it, but not too much to be unnecessary. I made sure all edges and corners had a decent and smooth coating, to avoid over sanding those areas and risk having MDF show through. I wanted to authentic look of trowel lines and texture, so I was not concerned with making the flat areas perfectly smooth. I knew I wanted to wait at least 24 hours to let it dry, but ended up waiting 2 days just to be safe.
Sanding. I tried using one of those hand sponge sandpaper things and it was terrible. So I broke out my orbital sander and tried it verrrrry carefully. It worked! (Phew!) I kept a light pressure, only wanting to smooth the physical texture, not eliminate the visual texture. (Does that make sense?) So I would still see the trowel line, even though it's been smoothed out. On the corners and edges I made sure I was VERY CAREFUL. If I hit the sander too hard on it, the MDF would peek through. But no worry, a touch up dab of white paint will eliminate those "oops" moments. I also learned a trick when I accidentally went into a raised bump sideways (see photo below) and it chipped off. (Dang it! I ended up using putty to patch that ding.) On any substantially raised area, like that bump, if I sanded starting straight on top of it, going downward as if I was pushing it into the table, rather than coming at it from the side, it didn't chip. Learning that was very important & helpful as I continued on the rest of the table.
The hard part was over! And it actually worked. I was pleasantly shocked. Last step was wiping it down completely (dust is the enemy prior to sealing), and use a concrete sealer. I will link the one I used (here) but I don't recommend it. So take this more as a DON'T buy that one. The sealer itself was just a tad harsh and ate at some of the concrete. Just very abrasive almost, revealing MDF peeks where they hadn't been prior. If I could do this step over, I'd just ask someone in the paint department of a hardware store what they'd recommend for sealing a delicate concrete surface. Also, the sheen matters! I wanted ours with a flat finish, so we bought matte sealer. If you want a little shine, just get one with a semi-gloss or gloss finish.
Here she is!
Here a few questions I anticipate, so I'll address them up front! :)
Q: Will it stain? Get water rings? A: I don't know yet. We sealed it, so we shall see. I also may give it a second coat of sealant using a new sealer, since we weren't crazy about ours. But time will tell and I'll update when I have an experienced answer.
Q: Can I put this outside?
A: If you weatherproof treat your wood (not the topsides of the panels because concrete will adhere to there, and then are diligent about concrete sealer... I assssuuume it would be okay? But I didn't intend for this to be an outdoor table for us, so I didn't put any research into finding that out.
Q: Can you do this with grey concrete instead?
A: Yes! The concrete coating I linked also comes in a gray finish!
If you have question I didn't answer, feel free to DM me on Instagram here!