Conservatory footings on sand?!

[Binnsy]

We are digging footings for a fairly large conservatory - however we have dug out 2 ft of pure sand so far. We have hit the house foundation raft - how much further do we need to go down? or can we tie it in with the house raft?

We are told the house raft is on sand also.

[welsh brickie]

if its on a raft foundation and pure sand ther is no point digging further
but I would suggest using reinforcing in the foundation.
Concrete should be 225mm thick reinforced with mesh cut into strips
thinner than the trench as not to expose steel to elements outside the concrete.
tie steel at joints and dont lay steel directly on sand it must be within the concrete 70mm from the bottom of the trench.

[radrom]

how about the damp proofing do you still put hard core on the top of the foundation floor and put cement again.