The time it takes to build a steel structure building can vary significantly depending on several factors, including the size and complexity of the project, the design requirements, the availability of materials and labor, weather conditions, and the efficiency of the construction process. Here's a general breakdown:

1. Design and Planning: This phase can take anywhere from a few weeks to several months. The complexity of the building's design, as well as the need to obtain necessary permits and approvals, can extend this timeline.

2. Fabrication: Once the design is finalized and the steel materials are ordered, fabrication of the steel components can take from a few weeks to a couple of months, depending on the volume and complexity of the steelwork.

3. Foundation Work: The construction of the foundation could take a few weeks. This phase includes excavation, pouring concrete, and allowing it to cure.

4. Installation: The actual assembly of the steel structure on-site can be relatively quick, often taking a matter of days to weeks, depending on the size of the building and the number of workers involved.

5. Roofing and Cladding: After the steel frame is erected, the roofing and cladding installation need one week.

6. Finishing Work: The interior and exterior finishing, including insulation, electrical and mechanical installations, and other trades, can take the most time, ranging from a few months to over a year.

In total, a small to medium-sized steel structure building might be completed in 6 to 12 months from start to finish, while larger or more complex projects can take 18 months to 2 years or more. These timelines are only estimates, and actual project durations can vary widely.