Building concrete shed with trees nearby in neighbours garden

The answer to this can be a bit like answering how long is a piece of string... The type of ground and the tree species can make a world of difference, as can the opinion of building inspectors. I had an experience where every plant root stopped about half a metre down at a clay layer but the inspector's book said that the roots might go to several meters down, so dig to that level to protect against the roots. In reality, it was obvious that the book was wrong, but the book said... Firstly, why a concrete shed? Do you mean in terms of the slide in concrete slat type things? They are not overly heavy so a raft might work well enough. Dig about 2' down and 2' wide where the walls will be, put lengths of rebar in to make four rebars like a box all round, so lay tow bars about a foot up and then two more at about 6-8" above that, then fill to height. The slab to make the floor should be 4-6" thick. If you are putting anything heavy in there, then a sheet of rebar mesh in the floor might help. If it's going to be a garden shed with nothing heavy in there, then I'd build a timber shed on a timber frame and stand legs on a concrete block to keep them off the ground so they son't rot. I've built dozens of these and the oldest is over 30 years old! It would be much quicker and cheaper and can be removed if ever it's needed to be with very little trace left. Whereas the concrete pad as I have mentioned above would need breakers to remove. It's all about what the shed is needed for. Don't build Fort Knox to keep a mower in but then don't build a Wendy House to put the crown Jewels in...

If you know that the surrounding ground needed piling another option would be a steel reinforced concrete slab. This would reduce digging to a minimum and also alleviate the root problem from neighbouring trees

I recently built a garage , due to trees and land fill site , building control insisted on raft foundation . As for sheds , there are loads available, ranging from timber frame , concrete pre- fabricated , I’d say piling , would be overkill , but if in doubt , speak to a structural engineer.

Always steel reinforcement