The Case of the Displaced Display
Dear Glass Detective,
What type of glass should be used for a display case in a gymnasium? We have a viewing window being installed near our playing area where volleyballs and basketballs might come in contact with the window? What type of glass would be recommended for the application—laminated or tempered?
Thank you for making contact with the Glass Detective with your question regarding what type of glass might be best for a display case located in a school gymnasium. Specifically, you say that the display case is very likely to be hit by volleyballs, basketballs and so forth. You close your question by asking “laminated or tempered?”
Gymnasiums, especially those in schools, are ripe for accidents. Sports balls, hockey sticks and, most importantly, people, can all come in contact with the glass display case. It is imperative that safety glazing be used and that impacts from all possible directions, including above, be considered.
This situation, proper glass selection for school display cases and trophy cabinets, is an issue that is actually of concern for many glass industry professionals. Thousands of schools that were built before safety glazing codes and regulations were put into place have glass that is really not as safe as it could be or should be.
As a grandfather of nine children, I have regularly visited a number of older school buildings for basketball games, plays, concerts and other similar events that my grandkids are taking a part in. Often, I have seen cabinets, railings, doors and display cases of various sizes glazed with glass that is not safe or up to code. On occasion, I have even pointed this out to people associated with these schools.
Once, I actually informed a teacher that an entire stairwell railing in a school was not only not up to code but had broken pieces of glass in it. This was an elementary school with hundreds of children running up and down this stairwell banging into unsafe railings all day long. I was told that the school was scheduled to be torn down and replaced with a new facility in about a year and that there was no funding for these types of issues at the time. The building was actually torn down about a year later and replaced with a very lovely facility and fortunately, no one was injured during that time span.
While by law, schools and other public facilities may not necessarily be required to replace these pieces of glass, they are still not as safe as they can and should be in my opinion. Of course, most school districts struggle to make their dollars stretch to cover all expenses to begin with and taxpayers constantly complain about rising tax burdens. I am personally pleased that you are looking to approach your school glazing needs in the best possible manner. As beautiful and wonderful as glass can be, it can also be a real hazard and school children in particular can be at risk.
For many years, wired glass was used in gymnasiums. Many people labored under the misconception that it was a safety glazing material. Nothing could be further from the truth. It would be a mistake to use wired glass in a gym or any hazardous location. Indeed there have a been a number of sad cases of children running into wired glass, which is actually one of the weakest glasses available, and getting caught in the wire. As they pulled their limbs out, they sustained additional cuts. There have been court cases and accidents. and wired glass has been banned in new construction in many school districts. It is not, nor should it have ever been an option.
While either the laminated or tempered glass will most likely meet your local code requirements (you will have to check), the tempered glass is substantially stronger and able to withstand impacts far better than the laminated glass. If the tempered glass does break it will make a bit of a mess, but the broken pieces can quickly be swept up. While the laminated glass would most likely stay in the opening if broken, because it is going to break much more easily, I would recommend the tempered glass product. Tempered glass is a type of safety glass, which is ideal in this situation. Not only will it better withstand impact, but it is also much less likely to injure someone if it does break.
You may also want to consider a “safety cage” which can be mounted over the display case (hinged with a lock) and while this makes whatever is in the case a little harder to view, it could virtually eliminate the breaking glass problem. You don’t say how big or substantially built the case is but you may also want to at least consider polycarbonate (Lexan) glazing material with a scratch-resistant coating.
Polycarbonate is approximately 250 times stronger than glass in terms of impact resistance. It has numerous uses in sports such as viewing windows for racquetball, protective barriers at hockey rinks, basketball backboards, and more. However, it is a type of plastic, which means that it is softer than glass and therefore scratches more easily. That is why adding a scratch-resistant coating is important. The optical clarity is also slightly lower than glass.
Depending on the level of abuse you believe the display case will receive, the tradeoff could be worth it. Polycarbonate would likely stand up to the abuse of regular impact from sports balls on a daily basis. Proper framing plays a great role in the strength of glazing as well. It is nearly as important as the glass itself.
Talk with your glass/glazing supplier and get their recommendation on this also. They will be able to meet with you in person to see the proposed application and make a more precise recommendation.
We certainly do appreciate you making contact with the Glass.com Glass Detective and wish you well with your project.