Design and Engineering

Custom glazing systems development schedules: When project timelines drive design choices

Harbor Point Custom Glazing Systems

The development of custom glazing systems requires adequate lead times to investigate the range of possible material and design options, as well as to accommodate testing, mock-ups and any other project requirements. At Bellwether, we find an average custom project timeline is between 18 and 22 weeks, considering:

  • 8-10 weeks for design, samples, and approvals from the architect and owner.
  • 10-12 weeks for material production and delivery.

Compressed schedules can sometimes be accommodated, with the understanding that short timelines result in tradeoffs in design flexibility and material choices, sometimes also leading to higher costs.

Three key areas that are important to keep an eye on to manage tight schedules effectively are:

  • Architectural approval turnarounds
  • Material lead times
  • Testing and mock-ups

We will review each of these items, using the example of the Harbor Point S4 vestibule that Bellwether designed and supplied for the developer. The schedule for this project was just 12 weeks from start to finish, accommodating an aggressive occupancy date.

Architectural Approval Turnarounds

On a typical design development timeline, we like to provide two rounds of drawings, with two approval cycles (for more, see Why Shop Drawings Should Not be the First Deliverable You Ask For):

  • Profile drawings are created in 2-3 weeks to confirm basic design intent and to agree on typical details and interfaces. We typically schedule a 1-2 week architectural approval period.
  • Shop drawings are created in about 2-3 weeks, with another 1-2 week architectural approval period.

The short timeline on Harbor Point S4 required profile drawings in 1 week, and shop drawings in 2 weeks, with 24 hour approval turnaround times. Since the developer was very hands-on with the design and process, and since time was the ultimate project driver, this turnaround was agreed to, at contract signing.

Harbor Point S4 Isometric Drawing - Custom Glazing Systems

Material Lead Times

Material choices are limited when you have an 8 week production schedule. Two things helped on this system design:

  • Patch fittings were used to anchor the glass, rather than point supported fittings. This meant that glass could be standard insulated glazing units without the need for holes which would have elongated production time.
  • The patch fittings themselves were designed as simple square shapes from the initial architectural drawings, so they could go into production without changes once engineering calculations were complete. Given more time, additional shapes, materials, glass make-ups, etc. could have been considered.
Glass Fitting on structural glass custom glazing system

Material Mock-ups and Testing

Material mock-ups and testing are typically casualties of a short project schedule. Laboratory testing and mock-ups can sometimes double the lead-time needed for a custom project: Mock-up materials used for aesthetic approvals and testing purposes can be created only after shop drawings are done. Then, if system changes are made after testing or mock-up creation, a new material production schedule must begin. In the case of the S4 vestibule, the design was based on a straightforward structural glazing system with silicone weatherseals. The performance of this design approach is well tested and proven in the field.

By approaching custom glazing system development with a motivated design team and a good understanding of project drivers and tradeoffs, it can be possible to get a very custom aesthetic in a relatively short amount of time. For more on the topic, see The Two Most Important Questions Architects Can Ask Themselves When Designing Custom Glazing Systems.