Slab/Raft foundation Calculations

[UKG]

Hi all

I'm planning a build of an outbuilding - 6m x 7m.

I was planning a slab foundation.. approx 6 inches of concrete with 4 inches of aggregate below.

I've spoken to building regs today and they have asked for calculations for the slab. Is this standard practice?

Can anyone recommend a cost effective way of getting these calculations? Has anyone had to do this?

many thanks
UKG​

 

[noseall]

Are you the same chap I replied to a wee while back regarding the design of a raft?

I think mentioned then, that a raft foundation was a pain in the erse. Is there any structural reason that you have chosen a raft?

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[UKG]

Hi yes you did reply to another post. Thank you. The main pain in the ar.. of the raft foundation at present is that building control are asking for an engineer to make calculations for the slab. A cost I can;t afford.

I wonder if you can help with another problem I have. The building will be next to a fence with the neighbour along the 7m length of the building. I want to get the building as close to this fence as possible. I'm now considering a 600mm x 1000 m strip foundation.

The garden is on a slight incline so I plan to level the area. Creating a circa 2 foot drop (at its highest) along the neighbours fence line. I plan to construct a small retaining wall using blocks laid flat.

Can you offer any advice on how to lay the foundations and build the wall as tight to the fence line as possible, with the consideration for the small retaining wall.

Can both walls be built off a strip foundation sat 800 x 1000mm? Or do the foundations for the single storey building need to be completely separate to the foundations for the small 2 foot wall?

Any advice on this is greatly appreciated.

With thanks

UKG

 

[^woody^]

A structured engineer (or other suitably competent person) needs to design a raft which is suitable for the ground and loading conditions.

 

[Paulg31]

Why do you need a raft? What's the soil? As above if it's a raft foundation you'll need a Structural Engineer to design it however if it's conventional strip footings and a ground bearing slab that's far simpler.