The Case of the Broken Balcony Wind Barrier

Question:

Dear Glass Detective,

I recently had a glass windscreen installed on my deck. The contractor used laminated glass and a number of cracks have appeared on several of the panels. Should tempered glass have been used instead of laminated?

Thanks for your help,
Bill C.
Laguna Niguel, CA

Answer:

Dear Bill,

Thank you for making contact with the Glass Detective with your question regarding laminated glass breakage in the recently installed glass windscreen on your deck. For the record, you were the first Glass Detective inquiry of the New Year (2020) and, while this does not qualify you for an award or prize of any kind, I thought you might want to know this. I’m going to guess that we will get about 200 or more requests this year and I would have responded sooner but like many others, the Glass Detective took a few vacation days during the holidays. But now I am back to work and I’m going to try to help you with your glass breakage problem. Here we go!

To start, I am going to suggest that you take just a few minutes and review a previous blog that we produced that compares laminated glass with tempered glass. I think a quick review of this information will help you understand the difference in laminated glass and tempered glass and be of benefit to you as you move forward. It’s a short read and we have received numerous positive comments about its content. While both laminated and tempered glass can be considered safety glass, they are not equal in their performance characteristics. The great news is that they can be combined—you can laminate tempered glass to other pieces of tempered glass. In my opinion, this is often the superior approach to many types of installations.

You did not provide photos of your deck’s windscreen, or dimensions, or any information about how it is held in place, so I am going to comment in somewhat general terms at this point. If this proves inadequate for you, please feel free to send us some photos of your glass problem with whatever additional information you can provide about the glass thickness and glass retaining/framing system. So with this in mind, my thoughts/comments are as follows:

1. There are very specific (prescriptive) building codes that may apply to your installation. Prescriptive codes are not performance-based codes but are very specific requirements that are to be followed indicating what products are to be used. For instance, if the windscreen on your deck is acting as a guardrail, it must be tempered/laminated glass or another “prescriptive material or method” as required by code.

2. Laminated glass, a truly great product used in all kinds of safety glazing applications, does not necessarily perform well in certain applications where it is of insufficient thickness to withstand the loads/force that it will have to bear. As an example, the thinner and larger the laminated glass used, the less ability it will have to deal with certain windloads, structural loads and other load forces.

3. Non-tempered glass (laminated or otherwise) does not always perform well when it is subjected to extreme heat differential. Your home is in sunny California where the heat variations on a glass surface can be extreme. Shading variations occur when there is lots of hot sun on a tinted piece of non-tempered glass at one side, and non-sun or even cooled air striking the other side of the same glass panel. This can lead to thermal stress that non-tempered glass cannot handle, in turn causing breakage.

There are other issues at play here but the above are my initial concerns and should be the first items addressed as you move forward with a final determination of what glass to use in your windscreen. So while you asked a very specific question of whether or not tempered glass should have been used instead of laminated glass, the very specific answer based on the information you provided is “possibly”. This is based, at this point, on the fact that the laminated glass is cracking and breaking. Something is awry that needs to be addressed.

I know this is not the exact answer you perhaps were hoping for and if you want to contact me directly to provide more information, I will try to be more specific in my answer. At this point, take a look at the above referenced laminated vs. tempered glass blog, talk with the glass supplier and installer that did the work for you, and then if you need more input from us, we will gladly try to provide it. There is no product in the world that can enhance the comfort and beauty of a home the way that glass can, but it must be installed properly and the glass selection must be appropriate for the application. I hope this information is of benefit to you and I thank you again for reaching out to the Glass.com Glass Detective. Good luck with your project.

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