The five most important points for the design of glass canopies

1. Did you know that the loads on canopies are often much greater, even twice as great, than the loads on roofs?

Snow loads on the roof vary by location, but can be around 60 lbs per square foot.

Therefore, loads can reach up to 120 lbs per square foot for some awnings due to snow being blown off the roof by the wind.

2. With such high loads, anchors are often a weak point.

In most cases, 4 fixings (one at each corner) will not be sufficient.

Depending on the size of the glazing and the loads, it is sometimes necessary to have 8 point fixings and sometimes even more.

Make sure the fixings can handle the loads.

3. Also make sure that the fixing system (spider arm+omega) can take the movements and tolerances of the structure

Spider arms should have fixed points (fixed holes), slotted/expanding points (oblongs) and free points (oversized).

Note: These holes are only for expansion. Tolerances in the glass and structure should be addressed using a separate element (omega).

4. I've mentioned this in several publications, but it's worth mentioning again.

Section 7.3.1 of CGSB 12.20 (the standard for glass calculations in Canada) specifies that laminated glass is required.

But are we going to use two layers of tempered glass with PVB?

5. Absolutely not! For an awning, especially one fixed with points, you have to make sure that everything stays in place in case the glass breaks (post-break retention).

The combination of tempered glass and PVB may cause it to detach and therefore poses a safety risk.

In fact, PVB should be avoided whenever possible for exterior applications, as it is more susceptible to weather and temperature fluctuations.

SentryGlas® (SGP) is therefore the preferred choice. It can be combined with tempered glass and remains safe even in the event of breakage.

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