Foundation for a brick built garden shed

[ROADRUNNER]

I have a brick walled garden shed that came with the house at te back garden that leaks badly whenbever it rains. Also one of the side wall has a crack in it. So rather than try and repair it, I thought I would demolish it and do most of the 'donkey work' myself and get a brickie to do the professional stuff. My proposed pet project/shed will measure (w)5.1m x (H)2.2 x (D)3.2m with a sloping felted roof. The rear and both the side will be of high density concrete blocks whilst the front facing wall will be twin walled with inner wall of concrete blocks and an outer brick wall. The soil is fairly heavy clay.

How deep must the foundation strip be? I ask because I have been receiving inconsistent advice from those wonderful guys from DIY chains. Some of recommended a depth 4", whilst a couple have said no more than 18", whilst one said that I should go down 3ft/1metre at the front and 2ft along the other 3 sides.

What would you advise?

[TheDoctor4]

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[harberg]

A shed that size , I assume single skin wall would, I think need no more than a one foot deep foundation. It does not mean a concrete "lintel" of a foot deep though but dig down to a foot. Than concrete of about 8" thick should be fine This obviously depends a little on the type of soil but lets face it... It's not a tower block. Just make sure that you give it plenty of time (28 days) before you start building on top.
Make sure that the top of the foundation is level all the way and square.
If you're building in blocks make sure that the size of the shed (thus foundation) is in multiples of the blocks plus joints. This saves your brickie having to cut.