The architect is usually the lead designer on buildings, with a structural engineer employed as a sub-consultant. The degree to which each discipline leads the design depends heavily on the type of structure. Many structures are structurally simple and led by architecture, such as multi-story office buildings and housing, while other structures, such as tensile structures, shells and gridshells are heavily dependent on their form for their strength, and the engineer may have a more significant influence on the form, and hence much of the aesthetic, than the architect.