Dufalite Clayboard

[Paul-man]

Well, yet another material I haven't heard of has been used in our 1990 house...

Speaking to the neighbour yesterday, this stuff has been used under our 200mm thick garage floor slab to protect against clay heave.
Do you think it will have been used under the other floors in the house?
We are planning an extension to the side and rear, should we use this under our slab?
If building on the existing slab (garage) I'm assuming my new finished floor will consist of insulation a DPM and a screed and not much else? am I right?
Waiting for my structural engineer to call so I can let him know what I found out!

 

[RonnyRaygun]

Speaking to the neighbour yesterday, this stuff has been used under our 200mm thick garage floor slab to protect against clay heave.
Do you think it will have been used under the other floors in the house?

If you've got RC floors in the rest of the house then almost certainly, yes.

We are planning an extension to the side and rear, should we use this under our slab?

If you are planning to use an RC slab, then yes.

If building on the existing slab (garage) I'm assuming my new finished floor will consist of insulation a DPM and a screed and not much else? am I right?

Yes, along with any floor finishes you are planning. Also hope that your SE is happy that the increase in floor load isn't an issue.