to break up existing concrete base or not for the new shed?

[john west++++]

hi, have a small wooden shed on a concrete slab. want to build a bigger breese block shed. should i break up the existing slab with a hammer or is there a way i can key in the extra sized new concrete base into the old existing one for the new bigger shed? many thanks john west

[BigWallop]

Thinking about the weight difference between the small wooden shed and bigger blockwork building, I'd really advise you put in a proper foundation (floating slab if you like, and using the rubble you take out of the old slabbed area) and a proper damp proofing system. The little wooden shed would have moved and breathed and been better suited to the damp conditions than a block built building, and the weight difference will be enormous.