When choosing double glazing for your home, the choice can sometimes be bewildering. Do you get the whole house done or just part of it? What style should it be? Will my ideal choice fit within the budget I’ve got?

One of the first things you should consider before you get an installer out to give you a quote is the type of glass to be used in your double-glazing fit. In the UK, there are eight types of glass that installers sell more than most.

In this article, we’re going to look at one of these eight choices – toughened glass, sometimes called “tempered glass”.


Introduction to toughened glass

Every type of glass goes through a process called annealing which produces the “first version” of a window pane. After that, it then goes through different treatments to alter the characteristics of the glass.

To make toughened glass, a manufacturer will put the pane into a tempering oven which bakes the glass to 620 degrees Celsius. The glass is then very quickly cooled which makes it incredibly strong.


How much does toughened glass cost?

Toughened glass is one of the more expensive options you can choose for your home, costing up to 25% more than standard, annealed glass.

Many homeowners getting double glazing for the first time or replacing their existing windows choose toughened glass because, over the lifetime of the glass, you’re less likely to need to repair or replace it.


How breakable is toughened glass?

When toughened glass breaks, it breaks up into really small pieces. You could say that it doesn’t break in the traditional sense but it does fragment. With normal annealed glass, it breaks into big shards meaning that there’s a real risk of cuts and injury, particularly to children and pets.

It’s for this reason that toughened glass is the type of glass that’s used on glass tables in your front room or on your shower doors.

Even if you want to have annealed glass or any other type of glass installed throughout your home, there one rule you’ve got to follow.

If you’re re-glazing a window below 80cm from floor level, a window that is 30cm or less from a door and up to 150cm from floor level, or it’s a glazed door up to 150cm from floor level, Building Regulations insist that you use toughened glass or something equivalent (like laminated glass).


Anything else I need to know about toughened glass?

Make sure that your installer drills as few holes into your toughened glass as possible.

Your toughened glass can withstand up to 24,000lbs per square inch of pressure (think of that as the weight of two-and-three-quarter African elephants standing on one inch of your pane) but their strength is considerably weaker where holes have been made to screw the pane into the casement unit (the thing that holds the glass in place).