In my last glassblog post, I presented a variety of observations about projects, trends and issues regarding glass, glazing, cladding, enclosures, façades and building envelope systems from the perspective of a professional services provider, working on various curtain wall and cladding projects—small and large; custom and standard; consultative, design and engineering—throughout the United States. This blog continues that theme, looking at topics such as Professional Engineer seals and drawings, jobsite observations, glazing scopes and more.
1. PE seals and drawings
PE sealed calculations are required on almost all curtain wall projects, but without bridging the gap to the next step and requiring PE Sealed shop drawings, there is no guarantee that the two products are coordinated. In fact, if only one item should require PE review and seal, it should be shop drawings. Those are the documents from which the wall is fabricated and constructed.
How many times have we seen shop drawings not match the calculations? (Answer – many times.) This is especially true if calculations are being provided by a third party or outside engineer, and the shop drawings are being provided by the client or manufacturer. There is no guarantee that the drawings match the calculations unless they’ve got a stamp on them.
What’s the point to the above? Doesn’t it cost more money to get PE sealed drawings? Yes. But not much more, and not compared to the cost of an incorrect installation. The installation should match the intent and detail in the shop drawings, which should match the calculations. Clients should build this into the cost of the project. It can also be considered a value to GCs and owners to reduce risk.
2. PE seal assurances
A PE Seal still doesn’t ensure that the wall has been properly detailed to accommodate resistance to air and water infiltration, or thermal continuity. A PE seal covers the structural adequacy of mullion framing, infill materials (usually), connections, anchors and movements. Air, water and thermal issues are separate “system design” or “system engineering” issues. And they are equally important. Water intrusion is far more common than a structural failure. Plus water is quickly visible and has a broad impact on interior finishes, comfort, degradation issues and life-cycle. Shop drawings need to communicate seal line continuity including transitions to adjacent systems.
Even if a project has PE sealed calculations and shop drawings, along with a properly detailed wall system, there’s no guarantee that the wall will be installed in the same manner. There’s also no guarantee that the drawings have outlined every occurrence or condition in the field. Folks in the field are critical to providing continuity from design to installation, but collaboration between field crews and design professionals should be encouraged. Both need the other.
3. Jobsite observation
Jobsite observation by the engineer of record or by a consultant can seem costly on the front end, but it’s far less costly than a forensic investigation due to a failure after the job has been installed. This is not uncommon especially on mid-rise buildings with multiple façade elements all having to be tied together.
It would be wise for building codes in the United States to require site observations (special inspections like ICC Chapter 17) for cladding and curtain wall projects, which are the realm of the “specialty engineer.”
4. Glazing scopes
When a design professional is quoting work to a glazing subcontractor, two scopes of work are important to define.
- The first is the exact scope of work that the glazing sub will be undertaking and for which they want work products from the design professional.
- The second is to specify the work products and services requested, such as, design-assist, performance mock up drawings and calculations, project shop drawings, calculations, fabrication drawings, thermal analysis, and others.
In addition, each scope should clarify, to the fullest extent possible, what actual deliverable will be received. Everyone has a different version of what a shop drawing should communicate. Defining expectations in advance is important.
Even with that definition, engineering and design shouldn’t take place in a “box.” Frequent interaction between stakeholders, including weekly huddles, video or face-to-face meetings, along with project plan definition and phasing is all critical to keep a project on track and to align with expectations and requirements.
5. Project plan
It’s all about “the project plan.” The better defined the plan, the better the results. Engineering is “the tail on the dog.” It’s subject to the project plan and design criteria. Engineering executes the plan and should seek to find value spaces and optimization within the plan.
Finally, collaboration is the best way to create an environment for a successful outcome on projects.
John Wheaton is the founder & co-owner of Wheaton & Sprague Engineering, Inc., also known as Wheaton Sprague Building Envelope. The firm provides full service design, engineering and consulting services for the curtain wall/building envelope/building enclosure industry, and works at “Creating Structure” for clients. He can be reached at firstname.lastname@example.org and on Twitter, @JohnLWheaton1.
The opinions expressed here are those of the individual author and do not necessarily reflect those of the National Glass Association, Glass Magazine editors, or other glassblog contributors.