A poured concrete slab. For a building that's handling vehicle traffic, heavy equipment, or serious workshop use, concrete gives you the most stable, permanent, and durable base. It won't shift, won't settle, and makes the floor inside the building feel rock solid.
If a full slab isn't in the budget right away, a well-prepared gravel pad with six inches of crushed stone is a strong second option. It drains better than concrete and still supports a heavy building well. Plenty of customers start with gravel and pour a slab later when the time is right.
