Help!: Screed on Hardcore

[qwertyking]

Hi all,

Another question. Would you recommend screed straight on hardcore with no concrete for a small kitchen floor? I would be looking at 80mm of Screed.

Thanks

[Scott]

I doubt that would be strong enough and where would the insulation be?

[nybor62]

what about damp proof membrane?

[Scott]

what about damp proof membrane?

I knew i was missing something else

[nybor62]

the way to go imo is as follows
about 100mm of hard core tamped down, abot 50 mm of sand tamped down, dpm make sure it also raps up the edges of walls, can cut it down later, at least 50 mm insulation, also put insulation around edges of walls, then concrete 100 mm , then at least 60 mm screed. hope this helps

[Ajax123]

Technically there is no real issue with this provided you can guarantee that the screed will acheive the sort of strength you would need i.e. C10 Mcc 175 (Gen 1 concrete) but bear in mind the screed will need to be controlled against cracking i.e. reinforcement. At 80mm depth you would be far better using a concrete with a coarse aggregate fraction which will provide a much more stable floor.

Other thing to consider if you are looking for building regs approval only a few authorities will allow this method

insulation is another issue but not constructionally speaking

[qwertyking]

Thanks.

Decided to go for compact hardcore, sharp sand on top, DPM, and then 4ish inches of concrete, insulation, UFH, SLC and then the tiles. The theory being having just concrete is better than having just screed.