Project complexity is directly related to the amount of time an architect has to spend designing and administering a project. Here is the typical project level of complexity scale:
ARCHITECTURAL PROJECT COMPLEXITY LEVELS
Group 1: LEAST COMPLEX
Industrial buildings without special facilities, parking structures, loft structures, warehouses; utility buildings.
Group 2: SIMPLE
Armories, apartments, cold storage facilities, hangers, manufacturing plants.
Group 3: INTERMEDIATE
College classroom buildings, convention halls, detention facilities, extended care projects, gymnasiums, laboratories, medical offices.
Group 4. COMPLEX
Aquariums, auditoriums, art galleries, communications buildings, theaters.
Group 5. MOST COMPLICATED
Custom residences, special decorative buildings, custom designed furnishings.
While the above complexity level scale can work globally, the above is the complexity listing of the State of Alabama (in the USA), which can be seen here: State of Alabama Median architectural fees. They use this register of complexity to determine their fees for architects, with the higher fees reserved for the most complex facility types.
The State of New Mexico, on the other side of the USA, has a similar ranking of architectural project complexities here: New Mexico Architectural Project Complexities (see item 188.8.131.52). For instance, in New Mexico, they rank the architectural design of custom homes in the “Complex” group.
Marcus Beale Architect, in the UK, has two complexity level charts associated with their fee ranges: one for New projects, the other for Existing (Renovation) projects. Their project type definitions of complexity general conforms to that indicated above. For instance, they indicate that what they call their “Class 5” category (Most Complex) includes “House and flats for individual clients, dental surgeries.”
One of the most interesting pieces of information coming from various definitions of architectural complexity levels globally is that the design of a house is among the most complex.