I had the same thing on my house.
Outbuilding concrete roof.
A grout will hold the flat concrete roof in place.
The term pitch refers to the slope of the roof.
To make a grout you will need sand and portland cement.
I put supports under the roof then used a petrol stihl saw to cut my roof away from the neighbours as close to the party wall as possible.
Add some water to get a flowing consistency.
The 4 inch solid concrete roof was joined to a mirror image on the neighbours side.
Foundations should be level square and built to appropriate depths for the location s frost line.
A concrete block shed should be built on a slab or footer foundation.
A simpler method is to build your shed floor like a deck with footings posts and a wood frame covered by plywood.
From doors and windows to trim and roofing.
For example the florida based company hurricane proof systems offers a 7 inch 18 centimeter slab of concrete in three layers.
Exact specifications vary but most concrete roofs are several inches thick.
Then cut the rest of the roof away a bit at a time and slid it off the edge.
Take a bucket and mix 2 1 2 parts of the sand with 1 part of cement.
For this step you will have to make the grout mixture.
Determine your desired roof pitch.
If your shed site slopes pouring concrete is a bigger job because you have to build strong forms and pour extra concrete on the downhill side.
A good foundation will eliminate many of the problems associated with building a concrete block shed.
A solid slab of concrete capping the top of your house.