From slab to kitchen floor

Continuing on from my last blog on the subject of flooring, I’d like to welcome you to the world of polished concrete floors.

Growing in popularity in both commercial and residential sectors, concrete and polished concrete floors are becoming more prevalent. There are several reasons for this:

  • The cost is the same as other premium flooring
  • Many buildings already have a concrete slab
  • They are durable and easy to clean
  • Each one is individual – they can be as polished or as dull as you want and you can add objects and colours into the mix
  • They provide great thermal gain

So to the process. While time consuming, there are six steps to great polished concrete floors.

Note: If you already have a slab, then skip the first four steps.

  • Form-work
  • Concrete pour
  • Vibrate
  • Helicopter finish
  • Diamond cut – x3 – depending on the desired finish
  • Clear seal

While the concrete pour doesn’t take long, the wooden form-work (think wooden scaffolding around the concrete reinforcement) prior to the pour does and it needs to be done well. Concrete is wet and heavy and will find holes or cracks in shoddy form-work. If this happens you’ll use a lot more concrete than budgeted and will probably end up with a substantial mess as the concrete slowly seeps down the path of less resistance (your home), so professional help is advisable.

Once the form-work is complete its time to pour the slab. This needs to be done in one swift action, so cubic calculations should be spot on – with a little excess –  before the concrete truck is brought in.

While pouring the concrete is relatively easy, there is an art to doing it and ensuring all bubbles are removed from the pour is done with a hand-held concrete vibrator (think edge trimmer or whipper snipper). This helps the concrete settle and should ensure a level surface once dry.

After pouring, the initial smoothing is done with a hand-pushed helicopter about the size of a lawn mower.

Note: Concrete floors employ the use of a lot of very heavy equipment. That’s the beauty of minimalism!

So now you have a smooth concret slab, as seen in many galleries and other commercial spaces. But moving into the residential zone, a diamond cut or three – depending on the desired finish – will give your floor a more polished finish.

Note: The diamond cut can be done wet or dry, but I recommend doing a wet cut to minimize dust.

Once again, the level of the cut is a personal preference. If aggregate (rocks) or additives were put into the concrete (eg. marbles or ring-pulls) you’ll need to cut further to see these. Again, the equipment required weighs several hundred kilos, so bringing in a professional may be the best way to go.

Once the desired cut has been achieved, the only thing left is to seal the floor. While standard clear concrete sealers and epoxy are commonly used, wax finishes (lower toxicity) for a duller sheen are also available.

Note: Wax finishes are slightly experimental, but good results can be achieved.

Sustainability tip:

While the initial off-gas from a setting concrete slab is considerable, the thermal gain from a concrete floor will outweigh the damage done to the environment and heating your home will be quicker and easier, so you’ll save on energy in the long term. Check out this climate-responsive house design using concrete.