Hoist Concrete Thickness Requirement
If you plan to install a 2-post hoist in your shed and your slab is a few years old or just 100mm concrete with steel reinforcement. You can test its compression strength to see if it can handle the hoist. To be safe, you need to install a special concrete pad for the 2-post hoist. It will add to the cost.
In a garage, a flat 4-inch concrete floor is sufficient for a 4-poster that does not need to be bolted down. It comes with special casters that allow it to be easily moved by one person. It only needs a standard 10 amp power outlet, 240V. The 4-poster is stable with the car raised, which is an important feature. You can use a trolley jack and modified jack stands to get the wheels free when the hoist is raised. And most jobs can be accommodated, even engine swaps or gearbox changes.
If your back can no longer handle working on the ground, you need to get a 2-post hoist. However, your shed concrete is only 100mm thick, and the 2-post requires a specified minimum of 100mm. But would rather have 150mm. People have given you different opinions, some saying that 100mm is fine. You must cut the concrete where the two posts will be sitting. Also, pour concrete additions approximately 1 meter by 1 meter by at least 800mm deep.
Ideally, you should pour concrete with a strength of 30mpa, and you will not require reinforcing with steel mesh as long as your concrete strength is in the vicinity of 30mpa. If you are going to be working on expensive cars and would like to use them for storage as well as working, follow the above procedure. It will create a strong and safe working position and environment for yourself and any other person using the hoist, especially where the main load will be acting on, i.e., at the base of the 2 posts.