Floor slab layers & services

[Toby]

I'm considering a replacement floor, mainly to get some insulation and a dpm under my feet, but my query is about the layering. I've got a picture forming in my mind like one of those geological sedimentary layer diagrams. It seems straightforward to have (from top down)

floor finish screed insulation DPM structural slab

But whereabout would one put the various services? i.e. soil, power, ch, dhw, phone cables etc.

floor finish screed + power, ch, dhw, mains water, cables etc. insulation DPM structural slab + soil (as in 110mm stuff not earth)

And if there were UFH in the screed layer, should there be minimum separation between that and cabling? I'm sure there's a convention, although Chudley&Greeno don't shed any light, & not much in my building regs guide.

Toby.

[Mike Taylor]

In general most architects etc would do the following from bottom up drainage goes in first laid in shingle or concrete if prefered

150mm layer of well compacted hardcore toped with 25mm layer of sand On top of that would go a 1200 guauge polythene dpm On top of that 70mm Kingspan TP10 insulation or equivalent On top of that 100mm minimum concrete floor slab possibly with reinforcing mesh in On that would go any water pipes well protected from the concrete. In general electric services do not run in the floor except where necessary. These generally run in ceiling roof voids and come down the ground floor walls. If you do run in the floor they again mst be protected in a trunking On top of the floor slab bwould be a 65mm minimum sand and cement screed up to finished floor level

The insulation can go on top of the slab but you would almost certainly need a thicker screed possibly with reinforcing in (chicken wire mesh is the norm for the screed) On top of th screed would go any floor finishes suh as carpet etc

[Toby]

Excellent, thanks for that, I've just received the following as well:

150mm hardcore topped with compacted sand 100mm slab on dpm 100mm insulation panels Water pipes cut into surface of polystyrene 100mm reinforced screed with UFH tied in to mesh. All cables from from above

THe power in the rest of my ground floor is below suspended timber floors, and this was taken into the rear solid floor area at skirting level. It will now descend from above.

Toby.