Tempered Glass Best Practices

19 Temper 3

You know what tempered glass is, and where it should be used  around your house. But should doesn’t necessarily mean that it will. Construction is complicated, and to some people, codes are suggestions more than rules.

Best practices exist to make sure things are done right the first time. They’ll also help make sure you’re getting your money’s worth for where you’re investing on your family’s safety.

I went to a destination wedding once at a reputable enough resort. People got drunk and a friend ended up walking through a glass door. Was it the door’s fault? No. Was the door tempered? No again, and it caused a bloody mess. Could it have been preventable through best practices? Most definitely.

If you haven’t already, check out part 1 of the series on tempered glass: “Tempered Glass Can Save Your Life” and part 2: “Here, There, Temperwhere.”

Supply and legitimacy

Depending on where you live, you might actually have several glass and aluminum suppliers down the street. Softness of their aluminum aside, the glass should be good enough for most windows you might need. Tempered glass may be different story. Given that it should cost twice as much as regular annealed glass, you should be able to compare rates across different suppliers. If it sounds too good to be true, it possibly is.

You should be able to check if what you’re getting is the real deal visually. The National Building Code of the Philippines (NBCP) requires that glass with special performance characteristics have its description permanently etched on the panel. This should indicate the manufacturer’s identification, special characteristics, and thickness. But the marking isn’t always visible, or may be hidden in how its framed.

You can also try looking at tempered glass through polarized sunglasses. Invisible to the naked eye, tempered glass shows dimples or striations of light and dark, caused by the physical handling of the glass through the tempering process. It’s best viewed in sunlight though, so it’s better to check as your panels are delivered before they’re installed indoors.

19 Temper 3 Visual Check


Once you’ve settled on a supplier, and it’s time to make your house weather tight –
Make sure the conditions at the site are ready for glass installation.

Ideally this should involve coordinating with the supplier ahead of time to find out what kind of preparation they’ll need built to receive the glass. A technician should go to the site and make shop drawings and glass cutting lists based on the design intent, reflecting actual site conditions. 

19 Temper 3 Sill Slope

As with everything, it’s better to measure twice and cut once. With tempered glass, get it wrong and you can’t do anything about it afterwards.


Given how temperamental it can get to work with, everyone should be familiar with the design intent for the installation for the tempered glass.

If you’re looking for something frameless, then remember to consider the additional length that the glass needs to be embedded into the floor and ceiling for it to mount properly. You’ll be forced into top and bottom frames if you’re not mindful.

Depending on the size of the panels, you might need vertical glass fins, spider clamps, or a combination of both for additional support. If that sounds less than ideal, express your concern early on. In the case of the spider clamps, any holes that need to be cut into glass needs to be done before the tempering process. The process is irreversible.

19 Temper 3 glass fins.jpg

The complexity of construction demands that members of a construction team understand their scope, as well as everything that touches it or would be affected by it. A glass supplier should coordinate with the general contractor to understand the materials for the flooring as well as how it’s installed. Embedding glass in a tiled floor entails a different set of challenges from doing the same in polished concrete.

Review shop drawings to make sure they reflect all of this as well as what possible tolerances between panels would be acceptable. You’d be surprised at just how wide of a gap some suppliers would try to bridge with sealant.

Contract until installation and beyond

Before any sign-offs or down payments, you’ll want to make sure your contract covers installation. This will protect you from any damages that might occur in transit, delivery, or mounting. Pay extra for warehousing if necessary. You don’t want glass sitting idle on site where it can be destroyed by a careless turn from a fatigued carpenter trying to maneuver steel framing into place.

You’ll also want to make sure you have a warranty for anything within reason. Acts of god like the occasional storm throwing a tree through your perfect picture window aside, your glass should stand up to traffic vibrations, and being buffeted by winds. It should also account for building creep as your house adjusts to the day’s heat and night’s cold and it settles into its place. Its not the glass that’s in question here, but rather the installation methodology. The detail should provide enough leeway for a little bit of movement while holding it tight enough to be secure.


Best practices bridge the gap of knowing what’s needed where and why, with the how to get it done. When it’s too important to get it wrong, it’s up to you and your architect to make sure you’re getting your money’s worth for the safety your family deserves.


Quick Questions, or have your own stories of running into glass doors?
Email homebydesignph@outlook.com or leave a comment.

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Jiddu Bulatao

One thought on “Tempered Glass Best Practices

  1. Here, There, and Temperwhere? – HOME BY DESIGN .PH

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