Breeze block shed/workshop/outbuilding

[CaptainMAD]

I currently have a 4m * 3m breeze shed at the bottom of the garden but want to replace it with one that is the full width of the garden (again in breeze block). The concrete base of the existing shed has cracked in half and I don't want the new one to do the same.

The new building will measure 7.5m * 4m and will be partitioned into shed/workshop areas - no really heavy load will be moving over the base like a car etc.

As my builder cannot start for another couple of weeks I want to get the base down ready myself to save a bit of time.

What's the best way of doing the footings/base for such a building?

I have considered the following two options, but am unsure which would be best (or is there a better solution?):

1. Dig a 9" deep trench around the base of the building wall perimeter. Place 12" boarding inside the trench and fill with concrete so I have a 12" thick base with 3" above ground level. Once set dig out the inner area to 6" fill with hardcore then 3" of concrete (would this need re-enforcing with steel with it being a fairly large area?)

2. Excavate 6" over the entire shed area, batton the perimeter fill with hardcore and place 4" of concrete over the entire surface.


Leaving the old base down and expanding around it, is not really an option.


Any suggestions welcomed.

 

[r896neo]

Raft footings are very difficult to waterproof the wall/raft junction.

Completely remove the old building and slab and start again properly.

Digging strip footings are the way to go for any masonry construction. Then pour a floor slab inside.

 

[CaptainMAD]

Thanks for the prompt reply.


So it's option 1, but fully remove the old shed and base beforehand?

Would 12" deep by 12" wide concrete be enough to support the building, or would I also need to add some steel grid before pouring the concrete to strengthen the footings?

The construction is going to be single skin 4" breeze with several support pillars on the longest sides and a Single skin steel roof.

 

[r896neo]

12'' is far to shallow to dig for a foundation for a building. You'd need to be at least 450mm down preferably 600 to get to solid ground