Supplemental Training: Ordering out of Square Glass

Ordering glass from a fabricator is a key part of every glazing project manager’s job. It can be pretty complicated: you have to account for the type of glass you need, quantities, sizes, coatings, thicknesses, edge work, and the list goes on …

But it gets even more complicated when you throw out of square glass into the mix (glass that is neither square nor rectangular). These out of square pieces can take on all sorts of irregular shapes, so fabricators need extra information to make them. Simply providing your fabricator with dimensions isn’t going to cut it.

Typically, there are two ways to order out of square glass:

  1. You provide your fabricator with a template cut onsite to the exact size of the pieces required, or
  2. You provide a drawing with all key dimensions clearly marked.

An example of out of square pieces assembled. While the finished product looks great, the irregular-shaped pieces increased the complexity of the ordering process.

Let’s look at both ordering methods and their associated pros and cons.

Method 1: Creating a template

Most glass suppliers are equipped with a pattern digitizer or similar equipment that can take an image of a piece of glass and translate that image into a digital file that can be input into cutting equipment. Pattern digitizers can read all sorts of materials, so the template you provide doesn’t necessarily have to be made from glass. For example, you can provide a pattern made from cardboard, plywood, thick paper, or any other material, really, that can be easily cut to the required size. While the material used doesn’t matter, accuracy does. It’s crucial that the template you provide is dimensioned properly.

This is a simple and effective way to order out of square pieces because you can simply check that your template fits the opening that it will fill. If it does, you know the fabricated glass pieces will too. This method also eliminates the need to interpret dimensions or notes and the risk of misinterpreting the drawings.

Of course, there are downsides. One of them is that creating a template can be time-consuming for field crews. Another disadvantage is that this method only works if you have framing already installed. If you have to order your glass before the framing is installed, it won’t be possible to create an accurate template.

Method 2: Ordering from shop drawings

Your drafter will be able to draw any irregular glass shape using AutoCAD drawings of the elevations as a starting point. The process is pretty simple for an experienced drafter. First, they’ll need to trace the outline of the daylight opening (DLO), which is the actual glass size that is visible. Then they’ll offset those lines by the same amount as the “bite” of the glass, or how far the glazing is imbedded in the frame. Finally, the drafter dimensions the whole shape of the out of square glass piece.

Fabricators need to know the dimensions of each side and at least two angles. However, it’s best practice to also include hidden lines that outline the rectangular piece of glass from which the out of square piece will be cut. The drawing should also include the angles of all intersecting lines. See below for an example.

It’s also important for drafters to label every glass piece. This way, your field crew will know exactly where each piece should be installed. We recommend labeling drawings with the elevation number as the start of the tag so it can be easily matched to the opening where it will be installed. For example, for elevation “F”, individual pieces should be tagged as F-1, F-2, etc.

The images below illustrate the process of cleaning up an elevation drawing to create a template drawing that your fabricator can use to make your out of square glass pieces.

Which method is best?

Ultimately, the best method depends on your project requirements and also your preferences. To summarize, here are the pros and cons of both:

Method 1: Creating a template

Pros:

  • Saves time in the drafting phase by eliminating the need for detailed drawings of each piece
  • A simple and reliable process

Cons:

  • Can be time-consuming for field workers, especially if multiple templates are required
  • Must have framing installed to create an accurate template

Method 2: Ordering from shop drawings

Pros:

  • Can be done at any project stage, allowing you to plan ahead and keep your project on schedule
  • Allows you to easily order out of square pieces with a variety of shapes and dimensions

Cons:

  • Can prolong the drafting period and introduce complexity
  • Increases (slightly) the potential for errors during fabrication if dimensions are improperly labeled or read

Questions?

We’re available if you need help with out of square pieces or anything else related to glass and glazing projects. Just reach out via our contact page and one of our experts will be in touch as soon as possible.