Should you go for polished concrete floors?

I was worried about how comfortable the concrete floors would be for the little people who'll live in our house, but ...
Michele Powles

I was worried about how comfortable the concrete floors would be for the little people who'll live in our house, but they appear to be loving them.

How do you know if a polished concrete floor is right for you?

Throughout a lot of the build so far I've been talking about using our suspended upper concrete floor as the basis for our thermal mass. This only works if the concrete is exposed. If we carpet or lay timber over the top of it, we lose much of the ability for it to absorb the Northern light we're hoping for.

I bought the house we currently live in partly because the Tawa timber floors were just so gorgeous that I fell in love.

So it has taken me quite some time to come to terms with the fact we'll be living on a big block of concrete. 

What does living on concrete floors do to your body?

For me, this was a big one. I worried that living on a hard unforgiving surface might impact my body and more importantly, the boys' bodies. So I had a chat to my Osteopath, Nick Karuna – Director of Well West Health Care.

His family live on a concrete floor, and if he built again he'd choose to go with concrete the second time too. Their reasons for choosing it were to avoid the dust that carpet does such a good job of trapping, and which gives his wife a bunch of health issues.

He says that there are problems with this type of floor increasing heel strike pressure as there isn't the dissipation there would be with a softer furnishing because there is no rebound (as there would be on say, a wooden floor). After working with lots of people in the film industry too, he notices issues with the outside of the lower leg taking strain from standing around with incorrect posture in a concrete warehouse all day.

For him however, these are all easily mitigated by keeping the body strong and being conscious of your posture and walking style. And for him he doesn't think it's a strong enough reason to not utilise the benefits of a concrete floor. 

I have to admit, that did make me feel better.

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Is it more expensive?

Most new New Zealand homes have their floor slab poured in concrete. However, most will then put carpet, timber or something else over the top.

We will have carpet in the bedrooms (and choosing that will be a whole other process - I'm already dreading it).

But we're sticking with concrete for two levels. Pouring the suspended concrete floor is more expensive. About 10-15% more compared to a standard particle-board floor in our case, but as I said, it forms a big part of the thermal mass to trap some of the (free) heat for our home.

If you want to polish your standard foundation floor, it's about equivalent to an expensive carpet or a mid-range solid timber overlay - getting the guys in to grind and polish is an extra cost, but you don't have to fork out for something on top of the concrete. You do however, want to make sure your concrete pour team are good and give you as even a finish as possible otherwise when the time comes to grind that sucker, they have a tough time getting it even.

What's the process?

Once your house is tucked up nice and dry, a team (hopefully as nice as ours) come and grind the top layer of the concrete away in stages, basically with massively industrial sandpaper. We wanted a "salt and pepper grind". This basically means we have a light sand all over and you see a few of the stones in the mix popping through, but it's mostly a soft grey rather than revealing the big chips of stone underneath. This is mostly an aesthetic choice. We liked the softer grey look rather than showing off the stones. It's also, happily, the cheaper option because it takes less grinding.

Side by side, polished (without the final glossy coat) and unpolished - what a difference. 

Another happy note for us was the fact our pour was a good one, so Bowie and Eru, our super friendly grind and polish team, got a really even finish.

Concrete is always going to be uneven and feature furrows and peaks, and when you're grinding it down, an uneven finish means big stones are revealed in the peaks, and none are shown in the furrows.

If you want the full rundown, for the salt and pepper they grind with an "aggressive 100" and then use grades of paper in stages from 100, 200, 400, 800 to 3000. Then they buff that baby into a shiny mirror of its former self.

And what about the finished look?

This is something I worried about too. Would I miss that inherently warm look of timber? Would the place look like some wannabe industrial post-modern complex? With the grind done, we'll cover the floor for the next couple of months and then seal it to make it pretty much child-proof and bring out the gloss.

But already I can see that it's not cold, in fact there is a lovely warmth to it, which I wasn't expecting at all, and even on a rainy Autumn day, it isn't cold underfoot, with just enough sunlight giving it some heat to hold on to.

You can also put colour in your concrete. It's relatively rare, says Bowie, but of all the colours available, black is most popular and I've seen one that looked super lux, but this takes a LOT of grinding to get right, so be prepared for some expense.

In our beautiful, glossy finish, there are a few cracks, one of them right through the middle of the main living area.

But I figure they're part of the process, so I'm thinking of giving them the stage rather than trying to hide them: perhaps a fine line of gold paint through the centre of the crack? I'll let you know what we go for in the end. 

MORE ABOUT MICHELE'S NEW HOUSE BUILD:

* Introducing the family and the build

How to price a new build

* How to find a builder

How to get resource consent

* How to work around rain

* How to: concrete foundations

* How to: build an outside office

How to: sell your own property

How we sold our house by ourselves

The truths of building: you're bound to change your mind

Timber framing goes up

How to cope with the stress of building a house

A baby, an apple tree & a broken arm

* Where does a roof shout come from?

* When an inspector calls 

* How to: Build a house in Nepal

* What you need to know about windows

 - Stuff

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