Foundation depth?

[Expertboy]

Hi,

I'm going to dig out a foundation to build a small "brick built" shed about (approx 6ft x 4ft) in my garden.

The ground is clay and i have a large Leyland conifer tree about 1 metre away from the new build.

I have crawled the net and this site but am confused on a safe depth for the foundations. From what i have read i was looking to dig out a foundation of 1 metre, would this be suffice?

Any help appreciated as this isn't really my field.

 

[noseall]

1m might be over egging the pudding for a shed. you could take root barrier precautions if you wish but this will involve going deeper than 1m.

i would dig down through the vegetable or fertile matter until you hit the clay. if at this stage you are, say, 600mm below ground level then lay the footings here.

removal of the tree later on may rehydrate the ground and cause heave so bear in mind this when locating the shed. but if this were the only location option i think i would just risk it.

 

[Expertboy]

You are a star, thanks alot.

 

[Shytalkz]

Wouldn't even bother with that, Nose. Dig out 225/topsoil depth, whichever the greater, put in type 2 and compact, cast 200 thick slab with A252 top and bottom and build off that.

 

[^woody^]

Just imagine, 1m deep by 450 wide foundations around a 1200x1800 area, and then the mound in the middle starts to cave in, so it needs some intricate shoring, and before you know it, it turns into a major engineering project just to store the hose, flymo and a bottle of greenfly killer

Definitely a slab/raft type thingy

 

[Expertboy]

Just imagine, 1m deep by 450 wide foundations around a 1200x1800 area, and then the mound in the middle starts to cave in, so it needs some intricate shoring, and before you know it, it turns into a major engineering project just to store the hose, flymo and a bottle of greenfly killer

Definitely a slab/raft type thingy

Ive dug down to the hard clay, hit it about 500mm deep so i will stop there.

I'm gonna fill it in with concrete at the weekend. The building is to store my disco equipment in, i have a shed for the greenfly killer

I'm not going to touch the mound in the middle until i pour in the footings, after there solid enough i will prepare the base with hardcore.

 

[Shytalkz]

You might just as well stopped at 300, or less. If it's hard it's dessicated; if it's dessicated it means its below its natural moisture content, due to moisture extraction by vegetation and/or climatic variations.

If you don't put any rebar in, any volume changes will cause it to move and likely fracture both the footing and superstructure. Hence the suggestion of a simple raft, which would probably have cost you no more to construct either and would perform far better.

Heyho

 

[^woody^]

These snippits are pure gold from the wise old man from the east

 

[WilloxPerez]

A deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground.Deep foundations can be made out of timber, steel, reinforced concrete and pre-tensioned concrete. Deep foundations can be installed by either driving them into the ground or drilling a shaft and filling it with concrete, mass or reinforced.