Materials

Why to Include Glass Thickness in your Project Specifications

About half of the specifications that we see at Bellwether have detailed glass descriptions that include glass thickness as part of the description. The other half are more general, making the determination of glass thickness the responsibility of the bidder.

There are three reasons that you should include as much detail as possible about your specific make-up, including glass thickness:

  1. Aesthetics
  2. To ensure that structural considerations have been met
  3. To ensure comparable quotes from all bidders

Aesthetics
Glass thickness affects its tint, and thicker glass is greener in tone than thinner glass. As glass gets thicker, architects often choose a low iron option to reduce this green tint.

Unless glass tint is explicitly called out in the specification (clear, low iron, etc.), bidders will often quote clear glass to keep bids as competitive as possible. However, a laminated fin glass make-up of 3/4” over 3/4” clear glass will be relatively green. You will need to understand the exact thickness that your project requires during your design phase, in order to know how that thickness will impact project aesthetics.

Structural Considerations
By leaving glass thickness and sizing up to the bidder, you are assuming that they are doing the appropriate pre-engineering at bid time. Many do not engage in the step for the sake of time and cost. Instead, bidders often scale what is on the drawings for use in their bids. Conflicts can arise when thicker glass is indeed required, and the bidder does not have enough money in the job to meet requirements. The stage is set for disagreements before the project even starts.

Comparable Quotes
A well-defined glass make-up will ensure that all bidders are pricing the same exact make-up. This will make it easier for you to compare scopes, while ensuring that structural requirements are met by all bidders.

Determining the correct glass thicknesses during your design phase puts the engineering responsibility and costs on the architect. It is well worth the investment, however, since glass thickness is such a critical component of your project aesthetics and your structural requirements. For these reasons, glass thickness should be determined by the architect and included in the specification, and not be left up to bidders.