shed foundation

[spx]

I have a shed at the bottom of my garden that has large cracks which I assume is due to old subsidence (I live near an old mine). I am going to take the shed down and build a new one - my only concern is the footings.

The shed is built on quite a thick base (which is cracked); would I have to dig through the base to set new footings or could I just set new ones on top of the old base?

 

[Scoby_Beasley]

If you live over an old mine that's gonna be extremely deeeeeeeep footings
How bigs the shed ?

 

[neathblue]

I would remove the old base especially if its cracked, break it up and use it as hardcore for the new base.

 

[Mr Ben]

we have just done a base for a shed (light structure) 8' x 8' and it was 3" hardcore and 3" concrete. I guess if you have a problem with the ground (mine) then you'd be best putting a double this in. If it's really bad then seek help from a Civil Engineer. I'd agree with above and break up the old for hardcore.

 

[spx]

Thanks for the advice guys.

The shed is 4x3x2.5m. I was going to set an RSJ into the new footings to give some support - not a good idea?

 

[masona]

How are you going to build the new shed ? I would break the old base up and compact it down with new concrete on top. You could also dig a footing round the outside of the base.