Ringbeam for single story extension of standard brick and block

[Makeitstop]

Hi all,

 

As title suggests, what do people feel is a generally adequate section for a rc ringbeam for a medium sized extension?

 

Foundations will be piled and floor is beam and block.

 

There is no plan to go up an additional level, so it's just the single story of brick and block, with wall thickness of 340mm, coming off the rear of the house.

Edited April 9, 2021 by Makeitstop

[Russell griffiths]

450x450. Lots of groundwork contractors will say go 600 wide. But that’s to allow them to be less accurate with their measurements as the have a wider surface for the brickies to get the walls somewhere like in the middle. 

[Makeitstop]

That makes sense I guess, but it's been suggested by the architect that the beam size is 600 wide by 500 deep (on drawings for regs approval), even though in all earlier correspondence the beam size has been suggested at 450 wide by 400 deep. This has confused me a bit, and while in some ways it doesn't matter, it does mean more concrete and more waste removal.

 

I'm baffled as to why it looks that way now. I have asked but have not heard back yet, so thought I'd ask opinions here.