Asking the contractor to provide the design for a particular piece of a building project has been a fairly common practice for a long time. As Structural Engineers, we have done this for building components, such as wood trusses, steel connections, and precast concrete members. However, a more defined set of rules that govern this practice became necessary after the Hyatt Regency Walkway Collapse occurred in Kansas City in 1981. The Structural Engineer of Record claimed that the Contractor was responsible for the inadequate steel connection design which caused the failure. In that case, the Engineer of Record was held liable and ultimately lost his license. New York State soon responded to the judgment, issuing a proclamation that it was illegal for contractors to provide professional services. The design community responded with some very heated opposition and the proclamation was rescinded. Finally, in 1996, the New York State Board of Regents issued a modification to Section 29.3 which provided direction for “Delegated Design”.
Since that time, the wording has been edited along the way, but the primary tenets of that rule still apply.
Section 29.3 (b) (2.) The design of a portion or element of a building may be delegated to others when the following conditions are met:
- The design is for a component that is “ancillary” to the main components of the project.
- All of the design parameters must be specified by the Designer of Record. (for structural components this includes, but is not limited to, design loads, material properties, performance characteristics, allowable deflections, and applicable design standards: ACI, AISC, ASTM)
- The design shall be performed in accordance with the parameters specified by the Designer of Record.
- The delegatee must be licensed to perform the design and certify it.
- The Designer of Record must review the design and “approve” it. This is specifically intended to certify that the component satisfies the design requirements when integrated into the structural system.
- The Designer of Record shall state in writing that the component design conforms to the overall project design.
Take, for example, the design of wood trusses. The design standard for the trusses is governed under ANSI/TPI 1-2014. There are three important statements in that document that refer to delegated design.
||For trusses with clear spans of 60 ft. or greater, the Owner shall hire a professional to design the temporary installation bracing and the permanent restraint and diagonal bracing (this is also stated in IBC 2015). This function is not provided by the truss designer.|
|126.96.36.199||The Building Designer shall provide information to be used for…Developing the designs of the trusses. Some of the required information is listed below:
|188.8.131.52||The truss designer is responsible for each singular truss as it meets the design criteria established by the Designer of Record.|
The subject of permanent bracing is mentioned several times as it refers to the truss industries’ recommendations published in BCSI-B3, “Permanent Restraint/Bracing of Chords and Web Members.” This document addresses standards for how to apply the bracing. However, it states that for lateral forces due to wind and seismic, applied perpendicular to the truss plane, this bracing is typically specified by the building designer. We have seen many projects, designed by others, where the design of all the truss bracing is left to the truss designer. The problem with this is the truss designer should not, and cannot be held responsible for out of plane forces and load path assumptions. What typically happens in these instances is that the bracing simply does not get installed. I was called to look at two separate projects (neither of which we designed) where the wind blew the roof trusses over before the building was completed. In both cases, the truss manufacture took one look at the mess, stated that the bracing had not been installed, shrugged his shoulders, and walked off the job. My conclusion, in both cases, was that the truss manufacturer was right. Furthermore, neither project met the rules of the Board of Regents, Section 29.3.
Taking this several steps further, we were asked some time ago by a contractor to quote a fee to provide engineering to design a salt barn. He was bidding the project and he needed to include a fee for the design. The project was for a local municipality. It was originally “designed” and put out to bid by a local A & E firm. The plan dimensions and the roof height were given for the structure, but the design of the building, including the framing, foundations, and concrete containment walls, was left to the contractor. The only design criteria specified was the roof loads. This project presented two issues.
- The municipality was paying twice for the design. First to the A & E firm for a design they did not do. Second to the contractor for what should have been provided in the first place.
- This project violated at least three tenets of Section 29.3, possibly more.
That may be a more extreme example, but the pitfalls of delegated design can have unplanned consequences. A contractor should not have to hire an engineer to provide design, just to put a bid together. Delegation of design is a useful tool, but there must be enough information on the drawings to bid the project. For example, using delegated design for light gauge metal curtain wall framing is an accepted practice. But the contract drawings should indicate a stud size, gauge, and spacing so that there is enough information to bid the project. The detailing and connections can be left to the delegatee, as long as the design parameters are specified.
At HSE, we strive to produce projects that are well thought out and detailed enough to put a reasonable bid together. As the Engineer of Record, we are responsible for the building’s structural system, which means all of the structural components must interact and function as designed. This applies to all components whether or not they were designed by us. As Engineers, this is something we all need to do.
Jay R. Saylor, PE