by Jack Van Meerbeeck
The use of glass over the last decade has grown tremendously. Not only in quantity, but also in the size of glass used. This trend is particularly noticeable in the architectural glass and automotive sectors. Just compare a car from the early 2000s with any car today. Architects favor larger and more energy efficient glass for a number of reasons, including aesthetic and optical needs. However, with bigger glass comes a bigger and more complex set of practicalities, and issues associated with it.
Consider the following:
1. Where does oversized glass or jumbo glass come from?
It was recently announced that two float manufacturers are opening jumbo sized float plants with an associated coater in North America: Guardian in Carleton, MI and Vitro Architectural Glass (formerly PPG) in Wichita Falls, TX.
This is welcome news. Finally, soft coats, domestic, in jumbo size 130 x 204 will be available. Larger than jumbo sizes can be obtained from European or Asian float plants with all the associated costs and practices in terms of shipping, packing and handling. This route can prove to be extremely expensive, given the special care requirements for these products.
2. Structural integrity and bearing loads.
Bigger or thicker does not necessarily mean stronger, but it definitely means heavier. Consider what processes will be utilized on an oversized piece of glass: tempering, edging, laminating, bending, etc. A tempered laminate is not safer than an annealed laminate, although it has better bearing characteristics. Every process must be carefully studied and prepared for.
3. Transport limitations before processing.
Regular glass is transported in North America on specialized trailers with a maximum limitation of 44,000 lbs., which corresponds to about 11 stoce packs. Jumbo glass transport necessitates lowboy trailers, with usually four stoce packs to a trailer. These trailer types are defined by the width of the glass packs (130” for jumbo = size of the ribbon coming off the float) being transported at a 4-degree angle, allowing tractor trailers to pass under regular bridges. Larger than jumbo glass requires special transport, which may not always be possible due to existing road infrastructure and carries a tremendous price tag associated with it. Shipping from overseas may involve on deck shipping.
4. Packing and handling.
Serious attention should be given to the crating, loading and unloading process, including storage and lifting systems. Similar issues apply after processing the glass if the size remains nearly the same.
5. Processing capabilities limited by equipment.
More measures to take into consideration are the size of tempering furnace, autoclaves, etc. Food for thought: the longest IG unit in the world, 18 meters long, and nearly 60 feet can be produced on a Bystronic line.
Laminating process can be limited by the maximum width of the interlayer. Interlayer in rolls like Kuraray PVB, are available in 130” width, SentryGlas sheets are at maximum, 232” x 99”. There are tricks to process two layers next to each other, usually at the detriment of optical quality.
6. Limitations on handling during installation.
Do your glaziers have the equipment to install these oversized lites? Huge lites on very tall buildings require careful planning in many areas such as safety, lifting, cranes, to name a few.
See the video below with a unique specialized lifter – very impressive!
7. Leave the specialties to the specialists.
Oversized glass needs to be imported. Specialized companies like Sedak can process glass overseas up to 49 ft x 11 ft approx. In North America companies like Agnora, RIG ,Viracon, etc., can process glass usually up to 130 inches x 230 or 300 inches.
8. Jumbo coated glass advantages (as of spring 2018)
- Can be domestically sourced and transported.
- Aesthetically more attractive to both architects and end consumers.
- Can be processed on equipment with a reasonable investment.
Depending on the optimization and mix: 2 to 4 percent yield savings on glass, which is huge in e.g. commercial IG’s.
Glass Size Reference:
Size North America Europe
Regular 144” x 96”
Jumbo 204” x 130 201” x 126” (20 ft container)
Jumbo XL 240” X 130” 236” x 126” (40 ft container)
Jumbo XXL 300” X 130” 275” X 126” (40 ft container)
Just a little food for thought based on personal experience and conversations with suppliers and customers. However, facts, figures and requirements are constantly changing at the speed of light in the glass industry. It will be interesting to see what innovations are to come involving oversized glass.