Jerry Built wrote:

Chris wrote:

I'm considering concrete beam and block to replace a suspended
timber ground floor.


Why?? That's the big question....



Can anyone give an idea of the cost comparison for concrete and
timber. I'm only looking at a room size of about 4m x 5m.


I don't know, but I should thing that a timber floor will be much
cheaper and easier to install than a suspended concrete one! Even
with insulation and nice boards....



No, it isn;tt. And its draughty as well because you have to let
underfloor spaces breathe or risk rot.

There are two classic asnwers - fill the void or use block and beam.
There is very little cost difference, and block and beam is recommended
where there are either huge voids, or risk of soil movement underneath.

Essentially with block and beam you dig deep foundation is small areas
top acvhieve stability: Then span them weith teh beams infilled with
concrete blocks. A quick brush of wet snad and cement seals them, and
then DPM, insulation and screed is applied over the top.

With a simple slab, you cahiev sbitlity by useing porous material - hard
core or limestone - that can take a little soil mobement, and then
appluy a concrete layer over teh top to lock it all in place. The loads
ar dustributed evenly, and if well compacted, its pretty stable on most
solis.

The same DPM insulation and screed goes on top later.

Apoart from sounding more hollow, there is very little difference in
them, except te slab is a bit warmer, as it doesn't have icy air
circulatig underneath in winter.

If you want a wooden surface, use laminate, or use battens on the screed
and traditional T & G boards.



J.B.