Delegating the design of portions of the building enclosure to specialty contractors has become common practice. How can project participants take full advantage of the benefits of delegated design while minimizing risk and avoiding common pitfalls? This paper draws from both research and professional experience to assist designers, contractors, owners, building enclosure consultants, and building enclosure commissioning (BECx) providers (BECxP). The authors present an overview of the motivations for using delegated design, common problems encountered, contract and specification language examples, and summaries of inconsistent policies and requirements in varying jurisdictions. Strategies are available to successfully implement delegated design within both traditional and modern project delivery methods. In traditional design-bid-build projects, contract drawings and specifications define project requirements. Meanwhile, newer project delivery methods that include design-assist and integrated project delivery render opportunities to employ specialty contractors early in the design process. With the advent of BECx, early involvement of qualified building enclosure consultants and BECxPs in a project can prove beneficial during both the design and construction phases.
BACKGROUND AND DEFINITIONS
Delegated design is the transfer of design responsibility for some portion of the project to a party other than the designer of record (DOR). The American Institute of Architects (AIA) defines delegated design as “design that is to be completed by the contractor or their subcontractors.” Ultimately, delegated design solutions require specific input from a licensed professional retained by a specialty contractor, supplier, or fabricator.
The transfer of design responsibility to specialty contractors has been standard practice in structural engineering for decades for projects including deep foundations, shoring systems, precast concrete framing, cold-formed steel framing, steel connections, and open-web wood trusses. While delegated design for building enclosure components and systems is not new, it is becoming more widespread. For some recent projects, DORs have written project specifications that attempt to delegate the entire building enclosure design, including transitions and interface conditions. A trend toward the increased use of delegated design results in more project control ceded to the contractor.
DORs may choose to use delegated design when they lack the knowledge needed to design specialized systems, such as curtainwalls, metal panel cladding, insulated precast concrete wall panels, or connections of these components and systems to the building structure. More recently, delegated design items have included systems such as air barriers. As part of the delegated design process, the DOR is responsible for providing performance and design criteria for the delegated design elements. Design responsibility is typically delegated by means of owner-contractor agreements and subcontractor agreements to a specialty contractor with expertise in a specific discipline. The specialty contractor must employ a design professional licensed in the state or region where the building will be constructed to complete the design such that it conforms to the DOR’s specified criteria.