Extension slab and foundations

[bally74]

I am building an extension to the rear of my property but doing this via a building notice and my bco isn't giving me much info all he has told me so far is that the depth of the footings should be 900mm from ground level. I have decided to use my existing damp proof as a reference point so am using ground level to be below that by 150mm. but I am a bit stumped on the slab, all he has told me is that i need 80mm celotex but he sais that I should know the rest, can anyone help me to find the right depths of appropiate materials for this please? ie scalpings, damp level,concrete, screed etc?

Thanks in advance.

Also do i have to use engineering bricks below damp course levels?

 

[freddiemercurystwin]

BCO's are not paid to chicken feed or advise that's not their responisbilty.