… floor levels are dictated by a heady blend of building reg’s, foundations, ceiling height and final finishes – you need to consider each of these – tricky!
What goes into the floor? Literally – hardcore, sand, insulation, a damp proof membrane – in many parts of the UK this will need to also be a radon barrier membrane, then the concrete or limecrete slab (more below). You should also consider slipping under-floor heating (UFH) cables or piping in there. Admittedly, UFH costs more, but it provides two things I like – no radiators and radiant heat (even heating throughout the room – no hot spots / cool spots and lovely warm floors).
As a slight aside, if you install under-floor heating ensure that you use appropriate materials when installing your finished floor – an appropriate adhesive for tiling or kiln dried (bone dry) wood. This will add extra cost but is essential.
The limecrete or concrete question is still one that is open to debate in my mind. Undoubtedly, there are environmental and ‘healthy house’ benefits from using lime. However, it’s also more tricky and expensive to use, is different from concrete (and therefore needs to be ‘understood’ by those working with it) and is more sensitive to weather conditions. My position is to use lime if the three B’s line up – that is, if the Build, the Builder and the Budget all allow or encourage the use of lime then use it!
For the record, we didn’t use limecrete at the barn.