During the Design Phase our scope of work includes performing third-party technical reviews of the contract documents produced by the Design team. What exactly does this entail, and how does it benefit the owner?
The basic intent of the design review, in accordance with the overall goal of the commissioning process, is to ensure that the contract documents meet the Owner’s Project Requirement (OPR) document.
In practice, this means verifying the following:
- Ensuring that the drawings, particularly section and plan details, convey the design intent with clarity and without ambiguities. Incorrect line weights, missing callouts, details that are too schematic are examples of items we sometimes identify as problematic. It has been our experience that poorly developed architectural details often result in headaches during installation as the trades are faced with the task of second-guessing interface details in the field.
- Analyzing how adjacent systems interface together. While coordination issues can sometimes be resolved later on during the submittal review process, we often find that issues that didn’t get resolved during the design process re-emerge in the shop drawings.
- Performing the “pen test”. This entails verifying the continuity of the building enclosure’s three main control layer (water, air and thermal) by highlighting each control layer with a pen. Any skip in the highlighting reveals a discontinuity which should be addressed.
- Verifying that the details comply with generally accepted best practices. While the final design is ultimately controlled by the design team, the commissioning authority takes on an advising role. We sometimes suggest modifying critical details, especially if they don’t appear to comply with guidelines published by industry associations. An example would be a brick relief angle which would not follow the Brick Industry Association (BIA) recommendations for allowing brick expansion.
- Verifying that the details match the specs. We review the specs and the systems that the designer intends to use, and we verify that the drawings illustrate the correct systems. It is not rare to see curtain wall details on the drawings when the specs actually call out storefront windows, or vice versa. It is important that the correct systems be illustrated to allow verifying that the interface details are properly designed.
- The specs should include appropriate performance testing, particularly air/water tests for fenestration systems. The desired testing parameters such as the required air pressure differential for water testing, or the extent and frequency of the testing, should be clearly spelled out in the Field Quality Control article. The specs should also indicate who will be responsible for providing the testing (at owner’s expense, vs. provided by the contractor).
Ideally, the design reviews should be performed at various stages of the design process: Design & Development (DD) phase, 50% Construction Documents (CD), and 100% CD. Early involvement allows us to orient the project in the right direction while the details are still under development. Obviously, it becomes much more difficult for the design team to implement recommendations later in the design stage.
As we have seen, ensuring that the final contract documents are clear and complete can prevent small ambiguities from becoming issues in the field. Resolving coordination problems during installation often results in unwanted delays. Additionally, details that have been fully worked out at the design stage are much more likely to end up being installed correctly and to provide the degree of performance and longevity that they are expected to provide, accomplishing the goal of the commissioning process.
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Eric Turcotte, Building Enclosure Project Engineer