The design/build delivery approach is preferred by some owners due to the single point responsibility.
There may be three different formats in the role of the design professional
Since most architects/engineers do not have a construction background, obtaining bonding and financing can be extremely difficult or impossible.
For example, New York State laws require that all members of the partnership be New York State registered architects, engineers or land surveyors.
Again, the laws of the state or commonwealth must be carefully examined. For example, a State might prohibit non-engineers from offering engineering services, and would consider a contractor who subcontracts engineering services to be in violation. In this case, a contractor might retain an architect/engineer on the owner's behalf, where the architect/engineer is directly responsible to the owner for design documents and design liability.
Since there is a contractor - engineer relationship, there are frequent conversations and planning with regards to constructability, scheduling, and cost control. It is likely that a detailed project scope, acceptable equipment and occupancy date have been prenegotiated with the project owner.
The responsibility of the design build team is to provide the contracted systems within the negotiated cost and completion date. It is the responsibility of the design professional to provide a design that meets applicable fire prevention and building codes.
It is a violation of professional conduct for "failing to report in writing to the project owner or to the owner's designated agent any unauthorized or improperly authorized substantial disregard by any contractor of plans or specifications for construction or fabrication, when professional observation or supervision of the work is provided for in the agreement between the owner and the design professional or when supervision of the work is under the control of the design professional.