Converting Suspended to Solid Floor

[zim]

Hi,

I wish to change our current suspended floor to a solid floor which is insulated and incorporates wet UFH.

 

I’ve ripped up a small toilet room to have a look and have found that we have about 4” of oversite concrete then a 200mm air gap with 200mm joist. Finished floor is about 420 above the concrete. There is a DPM below the concrete coming up to below the joist.

 

So how am I best getting a solid floor in there with the same finish height? There is about 130 sq m in total.

 

Could I put :

a layer of binding sand on the current concrete

DPM

+/- 100mm of concrete

+/- 200mm insulation

DPM

Screed

 

The 2 things that I’m curious about are:

1. Making sure I don’t start a damp problem!

2. Can I lay a slab over the oversite?

 

Thanks

Edited February 11 by zim