suspended wood floor in extension

[nervous123]

Am I correct in understanding that a suspended wood floor (in my extension) must have concrete oversite underneath? What are the ramifications If this wasn't done? Is it something LABC would have inspected on a Building Notice?

Thanks a lot.

 

[^woody^]

1 Yes

2 You could get a big tree growing there

3 Yes

 

[tkmax]

1. Not necessarily, DPM and 50mm aggregate is an alternative (Approved Document C)

2. Damp floor/rotten joists

3. Yes assuming they were notified

 

[stuart45]

Iv'e always used concrete, which I think gives a better base. I used to think it was the only way until the BCO said it didn't have to be done.
Remember that the concrete should be higher than external ground level, unless you lay it to fall to a drainage system.

 

[^woody^]

Some kind chap has posted something previously in post nr 11 of this thread www.diynot.com/forums/viewtopic.php?p=830276

 

[denso13]

The latest NHBC guidelines are -

(b) resistance to ground moisture
Provision should be made to prevent
ground moisture affecting timber floor
construction.
This can be achieved by either:
• 50mm concrete or 50mm fine aggregate
on a polyethylene membrane laid on
50mm sand blinding, or
• 100mm concrete.

But it would be advisable to check with the LA as I presume it is them who will be inspecting.

EDIT - oops just checked Woody's link which contains the above