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Hi Glass Detective,
I would like to build a glass canopy over an outdoor area. I envisage installing a mono-pitch glass canopy at about 30 deg pitch which is connected on one side (4.8m long – the highest side) to the house via a stringer. From the high point to the lower point is 4m. On the lower side there will be a bearer supported on substantial posts. So 5 purlins running high to low side supporting the glass. I have come across some 1.2m x 1.0m sheets of 10mm laminated glass left over from a commercial project and would be interested in your thoughts as to whether it would be suitable (it is a really good price!). I wonder about the span of the laminated glass? Also wonder how butt joining the sheets would go – how visible, if laminate would be affected by silicone etc. I’d appreciate your thoughts.
Thank you for contacting the Glass Detective with your request to assist you with some glass canopy work you are considering. Let me first apologize though for taking a few extra days to get back to you. You see, even the Glass Detective has to have a few days off every now and then and I combined the 4th of July holiday with a couple of vacation days and got away for a while. So thank you for your patience.
As to your questions about the canopy you are contemplating. Here my thoughts:
1. I am not allowed to comment on any engineering matters (those crazy insurance guys, you know) but I think you have thought this out pretty well and are off to a good start.
2. Please have someone of knowledge verify that your support system at both the house connection point and outer bearing point(s) is adequate for the weight of the system, any wind load issues, and snow load as well (if you live in an area where snow occurs).
3. As for the glass considerations, I am going to strongly recommend that you use a tempered glass (but please check building code in your area for confirmation of what is acceptable). Ideally, you would go with two pieces of tempered glass laminated together.
4. You may want to consider the use of a tinted glass for the project for heat gain issues or glare although you do not mention the orientation of the canopy in your memo or whether or not you are well shaded.
5. A silicone “butt joint” is workable with laminated glass products. Ask your glass supplier for recommendations on which silicones are acceptable.
6. Unless you are extremely mechanical and experienced with this kind of work, I don’t necessarily think this is a “do it yourself” project. You may want to consider using a local qualified glass company for this. They can also assist you with glass selection.
I hope this is of some help and I wish you well with your project.