Solid Concrete Floor Questions

[MadMonkey]

Hi all,

I'm after some advice on a solid concrete floor which I'm doing as part of workshop/summerhouse build. I'm doing most of what I can myself. Mainly the block work I wont be doing. I'm ready to start doing the solid floor and understand needing hardcore, sand, dpm, concrete and screed, but do I need an expansion gap round the concrete and can I omit having a screed layer if the concrete is level?

I'm going to have a laminate floor on top which will sit on some fibre underlay so not sure if screed is needed.

Many Thanks

 

[MadMonkey]

Oh forgot to add I'd be sticking some insulation in the floor as well!

 

[nickjb]

If you are insulating I'd put the insulation on top of the hard core/sand/dpm then pour the slab on top of that. You can put a strip of insulation all round the edge which completely isolates the slab from the outside world and gives a bit of an expansion gap.

No need for screed if it you can get it flat. If you can get it close you can always add a little self levelling compound.

 

[MadMonkey]

Thanks for the reply. That's great thanks. I was going to use polystyrene sheets at 75mm for the insulation for cheapness although I was told I should use 100mm celotex, would the polystyrene be ok for the edges?

 

[nickjb]

75mm poly is not much. It wouldn't meet building regs for a habitable space. For a workshop or summer house then it's your call. The walls and roof will make a much bigger difference so if money is tight then spend a bit more on insulating those.