Adding on to shed slab


Is it possible to add 2 inches to the side of a shed slab? I have an existing slab that need to be extended about 2 inches on two sides to fit my new shed.

The answer is no, adding 2 inches of concrete to your slab is not going to work. Two inches of new concrete will be too thin to bond with the existing concrete and they will offer no strength to support your shed.

The edges you are trying to extend are the most critical part of the slab because they will carry weight of the shed. Rather than adding 2 inches, I propose to add 12 inches wide. I would also add some L dowls (20 inches long dowls bent into L shape with short leg 8 inches long) 18 inches on center, drill and epoxy into the existing slab.

The 12 inch wide added slab will provide a better footing where you can add anchor bolts for the shed. When excavating, dig down 4 inches deeper than the existing slab and about 4 inches protruding underneath the existing slab. This will provide great bonding between new and old concrete.

Good luck

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