Concrete garage floor

11 Jan 2013
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United Kingdom
Apologies if this has been done to death- I've done a search but not come up with a definite answer to my queries.
Scenario- concrete block garage 6400 x 9100 internal dims with buttresses. Floor spec- min 100mm hardcore (it'll be 150 in places, subsoil wasn't particularly level) whacked down in 25mm layers, 25mm blinding sand, DPM, 100mm concrete- using readymix or whatever, hand-batching 6 cubic metres doesn't appeal. Loading- heaviest thing in there will be a 7.5 ton van.
Detail- to be in with a shout of getting a level floor I'm contemplating doing it in 2 batches- shutter off (and batten walls) for 6 squares about 3000 x 3000. Pour rear left, middle right, front left squares (with excessive DPM poking up above the shuttering), tamp finish. Leave for 2 or 3 days. Remove shuttering boards, lay and tape DPM for other squares, pour rear right, middle left, front right, tamp finish. Wait for about 2 weeks, slather with garage floor paint to give nice smooth finish
Does this sound reasonable?
Does this sound doable for 2 of us (I can get the concrete wagon to the garage door so no massive barrow runs required)
Do I need to put any sort of divider between the squares?
Does the DPM have to bond with the DPC in the walls (please say no, 150mm of black plastic is going to look sooooo shoddy)
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It might be worth having a read of this as it gives some good info on concrete slabs etc.

If you're pouring the slab in a few sections you might want to think about the joints. It might be worth having a layer of mesh in the slab so that it'll tie the different pours together and reduce the risk of cracking. Generally I'd say keep the joints to a minimum.

I would strive to do it in one hit, even if it means paying for either a conc' pump and/or more bodies and barrows on site.

Your biggest problem is achieving a paintable finish. Simply tamping is not going to work. You either need to maul your socks off with a floor trowel or get it power-floated. You could add a floor levelling compound later on but I doubt it will be durable.
Just to add.....

The dpm can be trimmed off once the floor is set and (as it is a garage) does not need to lap onto the dpc.
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Ta all. Pouring in one hit would be easy enough (wagon can get to the door)- trying to level a slab that size never mind finish it nicely is the worry. Might have an enquire see how much it would cost for someone to do it for me- with the concrete alone coming in at about £900 I don't want to spoil the job pennypinching.
And ta for info re DPM- I'm very glad about that

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