Concrete base for garden office

[Adiy24]

Hello,

I'm planning on building an "insulated panel store" garden office. I need a concrete base but I'm not sure how to compare quotes as they propose slightly different approaches (50mm concrete + 50mm concrete slabs, 100mm concrete, etc).

The soil is clay. How thick should the concrete base be for 15sqm garden office? What should I ask the builders?

 

[Wayners]

Some gravel then 100mm of concrete is normal I thought.
You will have a wooden floor in office. You aren't driving over it

 

[Murdochcat]

The top of our concrete shed base is about 2 inches above ground level. This ensures the airflow under the shed and keeps the base of the shed nice and dry