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At Issue: Delegated Design
Delegated design refers to components of a building that are engineered by an engineer engaged by someone other than the engineering design consultants (for example engaged by contractor, subcontractor, supplier and/or fabricator).
With respect to the involvement of Authorities Having Jurisdiction (AHJ), and municipal building departments as an example, work on smaller projects (typically falling under the Ontario Building Code Part 9) often sees building departments requiring engineered shop drawings prior to issuing permits, for example, engineered roof trusses. For larger projects (typically falling under the Ontario Building Code Part 3), although shop drawings showing specialty engineering items are important components of the construction documentation, these are rarely requested in advance by the building department. The practice of delegated design is commonplace and well understood, in general or in principal at least.
On these larger projects, complications relating to delegated design are not uncommon, though they often surface much later in the project in the Construction Contract Administration phase, which can be an inopportune time. These complications often relate to misunderstandings of roles and responsibilities, whether contractual or design related.
Effective implementation of delegated design in a project needs to be carefully coordinated during the creation of construction and bid documents to avoid potential pitfalls and ensure a successfully completed project. One aspect that is commonly overlooked is a requirement for the engineer providing delegated design services to have professional liability insurance. Any such requirement should be stated in Division 01 of the specifications.
The roles of the architect, engineer, contractor, construction manager, trade contractors and suppliers should start to be defined as early as Design Development phase in accordance with what the overall intent to be established by the construction documents will dictate. Careful consideration must be given to what is designed by whom, how it is presented in the bid and construction documents and how it is to be carried out during construction by the responsible parties. This integrated aspect must be clear in the bid and construction documents, discussed as a separate item in the construction kickoff meeting, as well as revisited during the shop drawing stage.
The following explores the various parties’ roles and responsibilities in designing, coordinating and managing delegated design from construction documents, through the bid period, to shop drawings to ensure a complete code compliant design meeting design intent.
Background
As noted in Practice Tip – PT.37 Delegated Design and Shop Drawings, in most cases, it should only be the engineered aspects of the design which are delegated. The increasing complexity of design, however, can introduce uncertainties as to what is acceptable to be delegated and where one party’s responsibility ends and another’s begins.
Delegated design is usually included for aspects of the design where the type of work is highly specialized and/or the details and engineering may vary depending on the chosen solution, supplier(s) or product(s). Elements that are identified to be engineered by others range by project, some aspects are common practice while others less so; they often include, for example:
- Engineering of steel connections for structural steel. While members are designed by the structural engineering consultant, the detailed connection methods may vary among fabricators and are therefore left to their discretion.
- Engineering of miscellaneous metal components. These are often guardrails or handrails, steel stairs, ornamental steel, washroom vanity supports and occasionally complete components that are not a part of the building’s structure and are designed by the architect. Here again connections, methods and precise detailing of components may vary among fabricators and are therefore left to their discretion.
- Engineering of hydraulic systems. This includes detailed fire protection system design, including sprinkler and standpipe design.
- Engineering of glass components. Similar to above these are often guardrails or handrails, or portions of these, not a part of the building’s structure and are designed by the architect.
- Engineering of assemblies or components, such as curtain walls, metal panel systems, acoustic ceiling tile suspension or metal stud framing. While overall design will have been included by the architects and engineers, detailed design specific to the supplier and installer’s products and selected approach to installation may vary - as such this detailed engineering is also left to their engineers.
The delegation of the design responsibility is designated by the contract in the construction documents via Division 01 specifications and the pertinent technical specification sections calling for engineered shop drawing submittals, in conjunction with notes in the drawings. Accordingly, responsibility to ensure the designated design engineer is engaged lies with the construction manager, contractor or trade that controls the related work and who directs that work so as to ensure conformity with the contract documents. Usually specific engineering is allocated to the subcontractor/supplier in charge of the specific work in question, but whether this is a completely separate engineer engaged by the contractor directly or by other subcontractors ultimately lies with the construction manager or contractor. In any case the submittal of complete, engineered, and sealed shop drawings is required.
In some instances, it is necessary to include requirements for the delegated design engineer to conduct field reviews and certify that the work indicated on the sealed shop drawings has been performed in general conformance with the engineered design.
Complexities Can Arise
Complications can arise due to misunderstandings of the various roles and responsibilities or as a result of oversights in allocating responsibility in the contract or in the preparation of contract documents. The risk of this increases as the complexity of the aspects in question increases.
Such complications usually amount to contractual issues regarding who is responsible for the aspect in question and to what extent. Should it be the structural engineering consultant or another (contractor’s / subcontractor’s / supplier’s) engineer? Unfortunately, this complication often does not surface until the shop drawing submittal phase, and depending on the item in question, this may be late in the project schedule.
Some ‘Lesson’s Learned’ examples follow:
A large institutional project included guardrails comprised of miscellaneous metal posts with glass panels and wooden top rails. These guards were among the last of the items for which submittals were received. Engineer stamped shop drawings had been received for the steel posts and the glass, separately; shop drawings had been received for the wooden rails, with no engineer’s stamp; additionally, prior to all of these, engineered submittals had been received for the cast in components to which the post would be anchored.
In the course of municipal inspections in preparation for partial occupancy, the Authority Having Jurisdiction (AHJ) requested to see the complete guardrail design with an engineer’s stamp to demonstrate compliance. The individual submittals received to date would not suffice, and discussions ensued between the owner, consultants and contractor over whose, if anyone’s, responsibility engineering of the complete assembly was. Neither subcontractor would take responsibility for the others components, but the need for an engineered solution of the complete assembly was irrefutable.
In this case, while the construction documents did clearly call for engineering in the pertinent specification sections, what may not have been clear is the requirement for engineering of a complete assembly. Ultimately the contractor hired a third engineer who gathered the pertinent shop drawings and engineering information, assessed it, confirmed the complete assembly and provided a report with an engineer’s seal.
In another example, an architect’s design included freestanding booths within a building. As the booths were not a part of the building structure and were comprised of miscellaneous metal plus glass framing they had not been included in the structural engineering consultant’s design or construction documents, though they had assisted in the design of the booths, which relied on the steel and glass working in concert to achieve the requisite structural capacity. Submission of shop drawings showing an engineered design was required for this structure
When miscellaneous metals shop drawings were received they were sealed, however upon review it was clear they had not been coordinated with the glazing subcontractor’s scope, for which submittals had not yet been received. Further, in review it was determined the caveats included with the engineer’s shop drawings did not take into account all of the required lateral load forces and the glazing subcontractor was not forthcoming in assisting or providing any engineered shop drawings.
Discussions in this case revolved around perceived ambiguity in the design (relying on both miscellaneous metal in concert with glazing), whose responsibility the design ought to be, the particulars as to what extent the structural engineering consultant should have designed, and what the subcontractor’s engineers should be responsible for (i.e. somewhere between only for connections similar to building structure, and for a complete assembly as per above). This was further complicated as this was a construction management project, with no general contractor, only several trade contractors.
In this case, Division 01 specifications and overall responsibilities typically found under a CCDC 2 Stipulated Price Contract were not present. The construction manager indicated that they can never take on the liability of hiring a third party engineer themselves and no one was willing to take responsibility for this engineering. Ultimately, the structural engineering consultant did so, simplifying the design to the point that basic engineered submittals from each subcontractor would suffice, albeit to the dilution of the design intent.
As a final example: a curtainwall and a punched window system each included portions directly adjacent to occupied floor areas and below guardrail height. The various specification sections included wording regarding required engineering, submittals, and requirements that glazing be designed to withstand lateral guard loads where applicable.
The subcontractor responsible for both the curtainwall and windows provided engineered submittals confirming that the curtainwall met the requisite design criteria, however for the windows they only provided submittals confirming the glass component could meet the criteria, with no mention of the complete assembly. When this submittal was returned ‘revise and resubmit’ flagging that the glass does not act alone to resist loads and the complete assembly must be considered, the construction manager replied that the glazing specifications referred only to glass and not a complete system.
The window specification section was not as clear as the curtainwall section. To further cloud the issue: in some instances the design incorporated miscellaneous metal guardrails in front of some windows but not others, without explicit notes in the drawings or specifications; the construction manager’s front end documents did not include specific notes delegating the responsibility for the overall engineering of an assembly; specification and codes read independent of context or one another do not necessarily spell out that more than one component may be required to meet requirements, i.e. a compete assembly.
The bottom line for any project is that it must meet code requirements and all contract documents are to be read in conjunction with one another, not as independent / unrelated pieces, it is a tacit requirement that the complete assembly is engineered to meet the requisite loading criteria. Regardless, so went the debate, with the suggestion that if no engineer would sign off on the complete assembly a guardrail might need to be implemented.
Lessons Learned
The above is an apt reminder to carefully coordinate and complete the construction document set and work with other parties to ensure the delegated design is in fact clearly delegated.
Ensure the design is code compliant and required parameters to be met are clearly specified. For example, that members are sized, relationship or reliance on other items are identified, and correct code references given, all of which are not contradicted by the design as shown or noted in drawings.
Ensure that the requirement for engineered shop drawings is clearly outlined in all the pertinent specifications sections and related scope is cross referenced in both specifications and drawings – for example including the other specification sections under “Related Sections” and with appropriate notes describing any specifics regarding the interrelationship of components such as two materials relying on one another structurally, where curtainwall or windows are acting as guards, or the need for partitions to support particularly heavy wall panels.
In Division 01 of the specifications include clear language regarding the requirement for engineering and required coordination, consider adding a ‘Delegated Design’ article or paragraph and paragraphs or sub paragraphs to Section 01 33 00 Submittal Procedures. If the project is construction management, work with the construction manager to ensure that they include the responsibility for overall engineering as a requirement of a trade contractor or subcontractor. Language such as the following might be considered in coordinating overall requirements, whether incorporated in a Division 01 Specification or used by a construction manager in their bid package:
“The Contract Documents include Delegated Design Components that require the Contractor to provide professional design services or certifications by a professional engineer related to systems, materials or equipment. The performance and design criteria that such services must satisfy are indicated in the construction drawings and relevant specification sections.”
“Provide submittals for Delegated Design services or certifications by a professional engineer, whose signature and seal shall appear on all drawings, calculations, specifications, certifications, Shop Drawings, field review reports and other submittals prepared by them.”
“Shop Drawings and other submittals related to the Work, designed or certified by the professional responsible for the Delegated Design, if prepared by others, shall bear such professional’s written approval when submitted.”
“The Consultant will review Delegated Design submittals only for the limited purpose of checking for conformance with information given and the design concept expressed in the Contract Documents. The Contractor shall not be responsible for the adequacy of the performance and design criteria specified in the Contract Documents.”
“Where the supply and installation of a “guardrail system” is called for, include for all support steel, miscellaneous metals, glazing, clips, fasteners, panels, engineering of complete assembly and submit Shop Drawings showing same. Such shop drawings to be sealed by an engineer experienced in such work and licensed to practice in the jurisdiction of the Place of the Work.”
“Where glass is likely to be subjected to human impact it shall comply with applicable specified safety glass and building codes requirements, including design to withstand lateral guard loads where the glass in question is not protected by stand-alone guards. Include for all support steel, miscellaneous metals, glazing, clips, curtain wall or window frame, fasteners, panels, engineering of complete assembly and submission of Shop Drawings showing same. Such shop drawings to be sealed by an engineer experienced in such work and licensed to practice in the jurisdiction of the Place of the Work.”
While the responsibilities for the engineering design consultants are captured in their contract with the client, it is noted that the contractor or construction manager is the designated coordinator of all delegated design professionals and the requirements for their services should clearly include not only engineering design but also field review to confirm installation has been completed per their design where necessary.
Additional Information
OAA Practice Tip – PT.37 Delegated Design and Shop Drawings
These articles do not represent OAA policy or guidance but rather are based on the opinions and experiences of members of the OAA and are prepared for the benefit of the profession at large.
Updated: 2020/Jun/16