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concrete floors - what underlies them?


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My builder is laying a concrete floor in the kitchen after taking out the old wooden floor in order to lay tiles eventually - he plans to lay the screed, the waterproof membrane, the metal bits (not sure what this is called) then pour the concrete. But in reading about this, a layer of sand is usually mentioned as having to go on top of the screed as well. Will it be a problem if this isn't there - should I insist on it? He also says it will dry (cure?) within a week but I've read that it can take a month!

From your experiences does anyone know how this should be done and what to expect ?

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We hae done a similar thing in one of our rooms, remove the rotten wooden floor, that was directly on top of an earthen one.

We had hardcore (6 inches) scalpings, the small rough stones (3 inches) then instead of sand we used sheets of foam (2 inches) this leaves a smooth service for the plastic sheeting, membrane, also extra insulation.  Then the membrane, then the concrete.

Think the whole lot cost 150.00 euros, hardcore was free and this included 30.00 euros delivery.  Think the area we did was 3 x 4 metres I think.  I'm a bit hopeless with sizes, but its a rough estimate you know.

Not sure if its ok to give the name of the supplier, so PM me for more details.


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    ok for a standard floor with no under floor heating you should have first

     a layer of hard core. then your layer of crush and run , then the sand layer binded in ,then the dpc course ,you can then lay an insulation layer now if you want , then the concrete with the wire mesh , and the final layer is the screed.

      but ...... if you are going to tile it ,no need for a screed layer this is just to give a flat finnish and to stop dusting , ok for carpets ect. so just lay in extra concrete..

you can leave out the wire mesh if you order pre-mixed floor grade.

the depth of the   hard core does depend on the ground conditions

  just make sure every layer is vibrated down with a whacker plate or simmilar ,and the sand layer has time to dry out and is whacked again when dry , because it will ( egg timer) into the crush and run layer



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1. Hardcore (10-15cm)

2. Sand (5cm +/-)

3. DPC Membrane

4. Concrete ( reinforced if large area)

As mentioned, compact the HC and sand layers first. The sand layer is purely there to stop the HC from perforating the DPC. If your builder has used 0/30 (calcaire melange) and compacted this well (ie. flat surface) then the sand layer isn't 'really' necessary. If he's used broken tiles, then beware!!!

Hope this helps.

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To completely dry, concrete takes one month per inch thickness to dry. So, if tiling on top, you should theoretically wait 6months for 6'' (150mm) of concrete. If final floor finish is permeable / porous, you don't need to wait so long.


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