Limecrete logicality

[urowho]

Hi, I have to admit to being confused about limecrete and its theory. I'm considering spending quite a bit of cash to have a chunk put into two rooms and a pantry in my house. My underlying confusion about the concept has been brought to a head as the existing concrete floor is dug out of one room and the limeash from another.

To start with there is a huge difference of opinion between two of the major suppliers of materials; one says the surface needs to be breathable as it transmits moisture to the surface and the other says that it does not and any impermeable covering can be used. If it is the first then I can understand the concept and how it might be better than a concrete floor with DPM. If the latter then surely by stopping moisture rising at a depth of 300mm or so it is no different at all from a concrete and DPM system, any moisture sitting in the area occupied by the floor will still only be able to exit at the edges. Is the supplementary theory that is just sits there with limcrete/glapor and somehow tracks along the plastic membrane in concrete?

The main reason I ask is that in one of the rooms, excavation of the two layers of concrete and DPM has reached a layer of sub floor with preserved sleeper walls from an original suspended floor with infill between them of very damp sand. As I wanted a wooden floor (parquet) I'm now asking myself if it isn't better in this room to re-instate it along with insulation and underfloor ventilation. I'd like to have parquet and I've no idea if this will work on limecrete or if I'd be better of with plywood directly onto joists with insulation below (actually I think I do know the answer to that;-))

Any thoughts on limecrete theory or experience with laying parquet on it would be gratefully received.

 

[88v8]

Well-ventilated suspended floor wins hands down.
In terms of well-ventilated, you have to ask yourself why the original floor was infilled. Presumably it failed. Diagnose and remedy before you start.

As regards the breathability thing.... the idea is that if there is sufficient depth of underlayer - LECA or whatever you're using as the bed - and if the groundwater pressure is sufficiently low, then the underlayer can absorb and release the moisture without it ever percolating to the surface.
Too many Ifs for me.

Breathable surface on limecrete.
Not parquet nor any other wood.
Actually, what matters in terms of the top surface is that it be bedded in lime and pointed in lime. What you lay is less important, quarries, pamments, stone, because like the walls, the solid floor will breathe through its pointing.

Ivor

 

[urowho]

Certainly the previous floor failed. The ground levels outside are above the nicely maintained ventilation grills under the bay window. It was bought in the late 1970s/early 80s by a surveyor who did the usual surveyor stuff of pouring concrete in, putting woodchip everywhere, getting planning permission on the surrounding land and moving to a tax haven;-)

As I said in my post; Ty Mawr are didactic that it will not transmit moisture and wood or other impervious finishes are fine, Mike Wye take the opposite view.

Whatever happens it would be a good idea to lower the ground levels and sort out the gutter which is leaking from the bay. The sand in fill at the bottom of the floor is wetter than Ventnor beach.

Thanks for chipping in!