ᐅ Structural Engineering for the Foundation of a Wooden Garage

Right next to our single-family house, a custom wooden garage measuring 6 x 9 m (20 x 30 ft) is planned, which will be built by a master carpenter. The garage floor will be paved, meaning there will be a strip foundation that extends down to the natural ground along the wall adjacent to the basement and is otherwise frost-resistant. The carpenter will design the garage structure according to snow loads and other requirements, but what about the foundation? A 40 cm (16 inch) wide strip foundation should actually be more than sufficient. Can a structural engineer simply calculate that? If so, what approximate costs should I expect? Or what about the company responsible for pouring the foundation? Alternatively, is there a standard structural design available for the foundation of a comparable prefabricated wooden garage? What approach would you consider the best?