Laying a new concrete floor.

[Alcazar]

Just been on the phone to my builder in France. he went up to our house and has quoted me about 3400 to put in a solid floor to one of our barns, about 75 square metres. I'm not that worried about the price, but he can't do it until the end of summer, and wifey is wanting it done sooner!
We talked about getting some "Redimix" type concrete delivered, but I don't feel confident that I could lay that sort of area before it "went off".
He also mentioned to me some sort of plastic shuttering that you leave in place, and it helps you to do it by hand, (mixing the concrete with a cement mixer), and giving you a level to work to.
Has anyone had any experience of doing this sort of job themselves, or any other tips? Or am I best to cut my losses and have it done as soon as my builder is able?
Alcazar

[Anton Redman]

Quick calculation assuming 15 cm depth means about 11 cubic metres of cement and say 22 tonnes to shift ? ( assumes concrete had a density of about 2 ) Could be wrong 35 years since I last opened a physics text book.

For a cement mixer I think you need a gang of three people one to mix, one to barrow and one to level. For piped ready mix you might get away with two but I would prefer three. Plastic shuttering used by neighbours who self built. Basically the worked in strips using shuttering as a level seemed to work OK and is shown in the French DIY books. It also allows you to work small section and therefore work single handed but it is still horse work.

I have also sent you a note / check your in box.

[Carnige]

The best way to lay a concrete floor is to shutter the barn off in to bays. You barn sounds about the same size as ours. Firstley make sure you have a good base to work on - this will usually mean 100ml of compacted hardcore with a blinding of sand to stop any sharpe points puncturing the membrane. The membrane should be a minimum of 1000 gauge - I personally prefer to use 1200 gauge. A bay running the length of the barn approx 2.5 - 3mtrs wide made from rough sawn 100ml timber will give you the 4" depth you require. A good tip is if you do alternate bays then you are never working across a freshly layed bay and the timbers can be removed and reused elswhere on the floor hence cutting down on the cost. My friend and I Used approx 30tons of Sharp sand and gravel(20ml down) and from start to finish it had taken about four days. I must say though we had a good neighbour with a digger.

Hope this helps

[sdt]

hi
i know in the uk you can get retarders to keep the concrete from going off to quick, i sure you will be able to get the in france, at least this will give you a bit of breathing space.

regards steve

[ljnw27746]

Divide your floor area up into about 1200mm squares then pour concrete into every other one, when set remove shuttering and fill in unconcreted areas.
this should give you a good level base and allow you enough time to compact and smooth out without too much difficulty.
That's the way I learnt in the Army( Royal Engineers).

p.s Make shure you lock up any animals or as sure as hell you'll have foot prints.

[Les Flamands]

The way we do it is:
Dig out barn floor to 250mm from your finished floor hieght (can be less in many cases), then shutter up doorways, then level off with 'Toutvennant' which is the cheap sand and aggregate you can buy anywhere. Put in your heavy plastic membrane and fix it to the wall about 500 mm up using battens and Hilti gun (for speed, but screws and rawlplugs or masonry nails will do). Put in your insulation (we use 50mm extruded polystyrene sheet which are tongued and grooved). Now fit your underfloor heating circuits, you can get special clips to clip it to the polystyrene. Calculate the quantity you need (75sq.metres by 100mm =7.5cu.metres). Order two trucks one with 4 cu.m. and the second with 3.5 cu.m. (don't allow any extra, as it's a pain to get rid of). Now hire a powerfloat (helicopter - 50 euros for the day). When the readimix arrives show him the powerfloat and get him to add a lot of water. Tip it in, rake it out, it should level itself but it is useful to have a couple of extra hands as it can turn pretty quickly with all that water in it. Once it is just hard enough to walk on without sinking in, start with the powerfloat which is easy to use and if you keep going back and forth you will end up with a level, flat polished concrete floor.
The result is so good you can tile straight onto it so you probably only need to dig out 150 mm instead of 250 mm which allows you 100mm for screed.
You can put in wire grid for extra strength but it's not really necessary as the floor is all poured at once.

Regards

Charles

[Me0wp00]

I know this is a very old post, but once it's powerfloated, what's the final floor finish like and do you need to seal it with anything

thanks

[just john]

I had my garage power-floated and the finished result was like glass, except around the edge of the walls, it still needed painting to stop the dust but looked as good as tiles [8-|]

[ventodue]

Like JustJohn said, powerfloat is a great finish for something like a garage, being smooth, hard and impermeable. (I've used it in warehouses, distribution units etc - its relatively quick and cheap and allows the use of forklifts etc without the surface being damaged).  Depending on the skill of the operator and the time taken on the polishing, the finish ranges from matt to a semi-gloss.   Whether you want it as a finish in a house is a matter of taste - I've seen it looking ok and I've seen it looking horrible.

But it does need to be done by people who know what they're doing - there's no going back if you muck it up ...  If done properly, no, it doesn't need sealing afterwards, but you can apply a cement wax which will make it shinier and tend to darken the finish colour.

HTH

Craig

[BIG MAC]

If going for a powerfloat finish you can also pop in a surface hardener..........

[Me0wp00]

can I ask the ready mix company to add some hardener into the mix, does anyone know if they would add a colourant too.  I'll get on the phone to them in the week anyway.

thanks

[BIG MAC]

I would think slim chance on the colour (potential contaminant of later batches) Hardener as an admix may reduce your dwell time too much its probably better to use a treatment based on silicate resins once the placement has been made. Surface hardeners also help prevent dust being given off by concrete floors.