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Preface
The preparation and review of shop drawings is an important part of the construction process. Items for which shop drawings submittals are required must be identified in the specifications, and a complete list of required submittals reviewed at the project pre-construction meeting. The process is a critical checkpoint to ensure that components which are manufactured off-site meet the design intent of the construction documents, and address any site conditions which may vary from those conditions shown on or anticipated by the construction documents. The shop drawing review process is also an opportunity to confirm that the project requirements have been clearly relayed to and understood by the trades and fabricators in order to ensure that the correct product is provided.
1 What shop drawings should show and the purpose of reviewing them is described below.
1.1 Detailing design and fabrication specific to a product
Shop drawings may detail aspects of design and fabrication that are specific to a product, and outside of the consultant’s expertise. Review of shop drawings for these items is an opportunity for the consultant to assess the fully developed design of those elements that are indicated schematically on the contract documents, to determine that they meet the design intent and that they interface acceptably with site conditions and other building elements.
For example, the construction documents for a building clad in precast panels will indicate the fasteners cast into the precast in a schematic fashion, as it is the responsibility of the precast panel supplier to engineer and detail the fasteners. The shop drawings will show this item in detail allowing the structural consultant (for the building) to confirm that the fastener interfaces as expected with the building structure and allowing the consultant to confirm that the assembly is compatible with the proposed method of achieving air and water tightness.
In a second example, the construction documents for a building clad in curtainwall will indicate mullion support points where deflection is to be accommodated by slip joints. The engineer for the curtain wall supplier will more fully detail these joints, as he will have a detailed knowledge of their own curtainwall system’s components, and will ultimately take responsibility for those details. The consultant is able to determine that the design conditions have been understood and addressed by the curtainwall supplier, through the shop drawing review process.
1.2 Documenting and detailing variations of similar components
Variations of a component are often described in the construction documents with annotations such as “SIM”, OR “REVERSE” OR “MIRROR”. Review of shop drawings prepared by the fabricator detailing these items provides an opportunity for everyone to check that the design intent has been correctly understood.
An example would be a multi‐storey stair for which typical guard and handrail elevations and required loadings have been provided on the construction documents. The shop drawings provided by the supplier will include elevations of all guards and handrails, allowing what is being provided to be checked for compliance with the construction documents and applicable codes, and to show how atypical conditions are being addressed. It is also an opportunity to examine anticipated conditions that may have changed due to field conditions.
2 Several important aspects of the shop drawing submission and review process are discussed below.
2.1 Submittal Schedule
The specifications should require the contractor to prepare and submit for review, prior to the contractor’s first application for payment (similar to the requirement for the submittal of a “schedule of values” prior to the first application for payment), a submittals schedule indicating when the various shop drawings, samples, product data, mock‐ups, photographs and certificates are to be submitted. This allows the contractor to demonstrate that they have identified all the required submittals and have scheduled them appropriately to allow enough time for review and for re-submission. By doing so neither the project schedule nor the consultant team will be unnecessarily burdened with numerous concurrent submittals. The size and complexity of submittals that may necessitate longer review periods than typical (which may have been specified) should also be addressed by the submittals schedule.
Review of the submittals schedule will also help identify any shop drawings that are not required and which should not be submitted for review. Prior to receipt of the submittals list prepared by the contractor, the consultants should review the specifications and prepare their own lists of required submittals, to check against the list provided by the contractor. Additional information regarding the preparation and maintenance of a submittal schedule can be found in the OAA/OGCA document “Joint Best Practice Statement Shop Drawing Schedule” available on the OAA web site.
2.2 Delegated Design
The specifications should also indicate which shop drawings require a delegated design engineer’s review and seal. If design is delegated to a fabricator’s engineer, the specific requirements for the engineering review should be noted in the specifications including the requirement that the engineer must be licensed to practice in the jurisdiction of the place of the work. State any requirements for professional liability insurance, both the amount (as required by the client) and how long it must be carried for.
Note that the engineer’s seal may not appear on the first submission of the shop drawing. Engineers are permitted to review and seal drawings prepared by others, so often the drafting will be done by the fabricator based on experience and not reviewed by the engineer until after the shop drawing is otherwise accepted by the consultants. Suggested practice is to mark the shop drawings with “revise and resubmit” status with the only note being to affix the engineer’s seal, assuming there are no other issues. A submittal requiring an engineer’s seal should not be marked “reviewed” or “reviewed as noted” if the engineer’s seal is not affixed.
This extra round of review will need to be accommodated in the schedule. Additional information regarding delegated design can be found in OAA Practice Tip PT.37 Delegated Design and Shop Drawings and the peer article Delegated Design: Complexities and Effective Implementation found in the Knowledge Base
2.3 Contractor’s Review
Upon receipt of a shop drawing submittal, the reviewer should first check for the contractor’s review stamp. If it is not there, or there is evidence that there has not been adequate review/coordination (such as dimensions indicating/requesting confirmation or adjacent material or scope not indicated) the submission should be returned immediately to the contractor. Although application of the contractor’s review stamp is supposed to mean that the contractor has thoroughly reviewed the shop drawings, marked up any discrepancies, and provided requested site dimensions, the quality of such review may vary. The question then becomes, what is the point of insisting on the contractor’s review stamp on the shop drawings? By returning unstamped submissions, it sets a precedent for the project in terms of following correct procedure. In addition it makes it more difficult for the contractor to avoid responsibility should issues arise related to the work shown on the shop drawings.
2.4 Reviewing for Design Intent Only
The purpose of shop drawing review by the consultants is to verify that the shop drawings correctly represent and implement the design indicated by the construction documents. Dimensions or information that do not relate to the design intent should not be reviewed.
As an example, the outside dimensions of a custom casting should be reviewed, but the wall thicknesses do not need to be reviewed by the architect as the wall thicknesses may only relate to the particular fabrication process or be of concern only to the structural engineer (who should then review the wall thickness). Aspects of the drawing which pertain to engineering should be reviewed by the appropriate engineer. Review must be limited to aspects of the submittal that are relevant to each discipline. Commenting on aspects of the submittal outside of the reviewer’s discipline and area of expertise may expose the reviewer unnecessarily to additional liability. If the consultant is concerned about something related to another discipline this issue should be discussed directly with the representative of that discipline.
It is critical that the shop drawings be forwarded to all the relevant disciplines for review, and that the reviews of various disciplines be coordinated. Finally, check the critical dimensions that determine that the components fit with each other and with the surrounding construction.
2.5 Use of Supplemental Instructions
Dimensions on shop drawing submittals are sometimes bubbled by the subcontractor or the contractor. If the dimension in question can be obtained from the contract documents, then the reviewer can simply make reference to the drawing from which the requested information can be obtained. If the dimension needs to be verified in the field, this should be noted. If the requested dimension cannot be obtained from the contract documents or through field verification, then a Supplemental Instruction should be issued which specifically addresses the requested information.
It is important to issue a Supplemental Instruction rather than simply marking the information on the shop drawing. By issuing a Supplemental Instruction the information is made available to the entire team and additional RFIs from other trades may be avoided. If the additional information is noted on the shop drawing rather than in a Supplemental Instruction, it becomes unclear who is responsible for the correctness of the shop drawings and may cause problems with the work of other trades.
2.6 Reproduction of Contract Documents as Shop Drawings ‐ Potential Risks
One of the issues of easily reproducing drawings is that drawings prepared by the consultant forming part of the construction documents are sometimes simply reformatted and annotated by the supplier or fabricator, then submitted as shop drawings for review. This approach can be problematic. The supplier or fabricator may not have thoroughly reviewed the contract documents, captured all the necessary information from various sheets, details, or specifications, or detailed their component of the work from first principles to ensure that they have understood the project correctly.
Secondly, any inconsistencies in the contract documents will be copied into the shop drawings, missing the opportunity for final coordination. For example, the supplier of open web steel joists may request a CAD file of the structural consultant’s roof plan, and resubmit that file as a shop drawing with additional annotations. However, there may be an inconsistency between the architectural and structural drawings, due to design changes or pending coordination. Site conditions may have resulted in changes from what is shown on the drawings. If the supplier simply copies and resubmits the engineer’s roof plan, the opportunity for an independent assessment while redrawing the roof plan is lost. This of course does not mean to suggest that the fabricator is responsible for final drawing coordination. It is however, an important part of the process helping to ensure that any coordination or site condition issues are resolved prior to further construction.
Another example would be millwork shop drawings. While the construction drawings may show the intended configurations, they typically do not show all of the details of construction covered in the AWMAC specifications. Copying the construction drawings does not improve the situation nor show that the required quality and construction standards will be part of the finished work.
It should be noted that incorporation of electronic contract documents/drawing files may be necessary for complex designs. The above noted concerns should be considered when reviewing such submissions.
2.7 Final Opportunity to Coordinate, Clarify and Confirm
There may be resistance on the part of the supplier or contractor to provide shop drawings. It is however, where specified or noted, a requirement of the construction contract, and a valuable final opportunity to coordinate, to address any site conditions, and to review adjacent conditions and how they may impact the installation or performance of the product.
Shop drawing review is an opportunity to collaborate and note any misinterpretations of the contract documents at a point when the issues can be far more easily addressed, rather than at a point in the construction process where the issues may cause construction delays and cost increases.
3 Conclusion
It is in the best interest of the entire team to ensure the preparation and review of appropriate shop drawings is earnestly included in the construction process and proceeds in a collaborative and timely manner. As noted in Atul Gawande’s “The Checklist Manifesto”, a submittals schedule is a form of checklist and is proven to be useful in successfully completing construction projects, all of which are considered complex.
4 Additional Information:
1. Checklist CH‐46 “Checklist: Typical Items for Shop Drawing Review” from the Canadian Handbook of Practice for Architects (CHOP) is an excellent resource, providing a comprehensive list of potential shop drawing submissions for a large scale project, and the items to be reviewed by the Consultant in the submissions.
2. Electronic Shop Drawings Review This article describes the process of shop drawing review prior to the extensive use of electronic documents, and a typical process for electronic markup and issuance.
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/11