Write the building before the price line
A named search does not state whether the project is relocatable or permanent. Record occupancy, planned service life, and whether the unit must move again after the initial set. Those three answers change the primary frame, the foundation interface, and the transport envelope.
For a sample brief, a buyer might write a 12 ft by 40 ft module, 14 ft eave height, and a 40 ft clear span. Those figures are buyer inputs, not a stock offer on this site.