self leveling concrete?

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Hi all..
I have a total of 43sqm of floor to concrete in an old terraced house.
I have used roughly 4.5cu.m to fill in void in main part of house consisting of material out of kitchen floor which comprised brick, earth, broken concrete, and wacked down..
I am now going to put 120-150mm of type 1 hardcore, dpc, 150mm of polystyrene, dpc, then 100mm of concrete.
Is there a self leveling concrete product that can be used which will give a final finish?
Ive got conflicting advice from various sources, any advice welcome...
Also, is there a major disadvantage of using 150mm of polystyrene v 100mm of kingspan.. its just I need to keep costs down.. (either is ok with the building inspector)
Thanks
legepe
 
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Pollystyrene needs more space as you know, also it can damage electric cable insulation. Other than that I can't think of any
 
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also it can damage electric cable insulation.
Not sure what you mean, how can it damage cable insulation..? it will have a full rewire.. any cables and pipes for plumbing will probably go underneath insulation
More space for insulation means less hardcore I need to shovel in..
 
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Is there a self leveling concrete product that can be used which will give a final finish?
No. Well there are some exotic specialist types that will need a specific supplier and expert team to lay it, and will cost many times as much but will never be as good as screed. But you are probably on a budget.
 
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Whats wrong with screeding?

Its a process designed specifically for levelling.
 
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Not sure what you mean, how can it damage cable insulation..? it will have a full rewire.. any cables and pipes for plumbing will probably go underneath insulation
More space for insulation means less hardcore I need to shovel in..
Basically the plasticiser will be messed up by the polystyrene and the insulation will be damaged.
That's why when you buy electrical goods in polystyrene packaging they always wrap the mains lead in a plastic bag before putting in the pollystyrene
 
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Doggit

You forgot the sand between the hardcore and the DPC, and you haven't mentioned what you're putting down afterwards. You can get flowable concrete that will get fairly flat (expensive), or you can concrete to withing a couple of inches of the final layer, and then get someone in to lay a screed, but if you're doing this yourself, then get to about half inch with concrete, and make sure the guys pouring it use a vibrating pocker, then you can lay self leveling compound for the final finish.
 
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OK thanks... never knew polystyrene could damage plastic.. there will be the DPC between the cables and the polystyrene and I would think the electrician should put the cables through some type of channeling.. the polystyrene shouldnt damage the DPC.. will it?
Yeah I forgot about the sand.. do you think a about a ton would be enough...?
I am on a budget... so I will end up laying the screed myself.. will ask the guys laying the concrete if they plan to use a vibrating pocker..
 
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Doggit

If the hardcore is well compacted, then you should get away with a ton of sand. one tone of sand equates to about .66 of a cubic metre, which at 43sqm come out at about 15mm of sand. But you still haven't mentioned whether you're laying tiles or engineered wood. If you're going to use UFH, then you need to insulate the sides of he slab as well, but there are some that will say you have to insulate on any outside walls as a matter of course.
 
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I floated and troweled a biggish concrete slab to a good finish but it was hard work and the walls weren’t built (massive post on here somewhere about it, was about a year ago). As above I’d advise the screed route in your case especially due to the size and the fact that you’re indoors and can’t tamp it and walk outside of it while doing it
 
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Ive a building regs app to cover the works.. and they insist i put 25mm kingspan up the walls to where the concrete will be finished, however i wont be installing UFH... I will finish with tiles in the bathroom and kitchen, the rest of it will be carpet.

As above I’d advise the screed route in your case especially due to the size and the fact that you’re indoors and can’t tamp it and walk outside of it while doing it

When you say screed route... it needs to be 100mm.. how can this be done? screed can only be laid 80mm max unless im mistaken? also where poss I need to keep costs down as much as poss on this...
 
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Doggit

If you want a thinner screed, then throw down more hardcore. Aim for about 70mm.
 
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If you want a thinner screed, then throw down more hardcore. Aim for about 70mm.
Im going through regs.. I have to put a minimum of 100mm concrete... with the way im building the sub floor.. brick rubble and earth to fill as much of the void as poss now i need to put 150mm hardcore , 15mm sand , dpc, 150mm polystyrene , dpc, concrete.
 
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Doggit

But if you want less screed, just add more hardcore; as long as it's compacted properly, a little more won't be an issue, or add a bit more rubble.
 
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Ok my question originally was - Is there a self leveling concrete product that can be used which will give a final finish? I guess that I will have to lay 100mm of concrete for strength and satisfy the building inspector, get it as level as poss, then from there put around 10mm of screed to get a final finish.. does this sound like it can be done?
 
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