Possibly could but now's the time of year when we see a lot of this,
Interesting read this....
Spontaneous cracking is an occupational hazard of many double glazing – particularly those at the cheaper end of the market. At any time of year, a window might suddenly decide to collapse inward, causing an unsightly (and heat-inefficient) shatter effect.
What causes this peculiar phenomenon to occur? In most cases, it’s a combination of many different stressors. In this article, we’ll shed some light on the subject.
In order to understand what’s going on here, it’s worth considering how a double-glazed window is constructed. Two sheets of glass are placed either side of a vacuum – or a layer of inert gas through which heat has difficulty moving. This creates a barrier which helps to contain (or repel) heat, and thereby keep your home at a stable temperature – and your energy costs down.
A double-glazed window is a sealed unit, which means that the pressure within it is constant, in contrast with the air pressure on the other side of the glass. This means that, inevitably, the glass will be constantly under very mild pressure. You might notice the glass of a double-glazed window slightly deform inwards, depending on the pressure outside. In most circumstances, the glass will be strong enough to withstand this pressure. But in some cases, it won’t – and it will implode.
It’s revealing that the peak time for double glazing breakages is during winter. This is a time of year that we experience colder outdoor temperatures – and we try to compensate for this indoors by using central heating. This creates a large difference in temperature on either side of the glass.
Square (or even round) windows are at the lowest risk of suffering a break. Why might this be? The answer lies in flexibility. Shorter panes of glass have less opportunity to flex than their larger counterparts. A tall, narrow window, then, will be at the greatest risk of suffering a break.
As commonplace a technology as double glazing now is, it’s still something that requires precise engineering in order to get right. There are many different practices and environmental factors at the point of manufacture which can produce short-lived windows. Let’s consider some of them.
Scratches
Creating windows involves, inevitably, cutting glass. But it’s important that these cuts occur only precisely where they’re meant to; even a tiny, imperceptible scratch at the centre of a pane of glass can create a weak point which the elements might later expose. This risk is greater when the cuts required are more complex, such as in bevelled glass.
Temperature and Humidity
We’ve already mentioned how breakages become more likely when the temperatures on either side of the glass contrasts greatly, but what about the temperature of the gas inside the unit? If a double-glazed window is created on a hot summer’s day, when the atmospheric pressure is low, then it’ll be at greater risk during the winter.
The same is true of the moisture within the unit. Double glazing manufacturers use a special substance known as a desiccant to absorb all of this moisture and prevent it from forming droplets inside the window. But this process, too, changes the pressure within the window, and so windows created on hot, humid days will be at greater risk when the temperature drops.
Not all desiccants are created equally, and some manufacturers look to slash prices by opting for the cheaper sort. Such desiccants will absorb not only water, but large amounts of nitrogen – which exacerbates any changes in pressure.
Strength of the glass
Of course, all of these problems can be guarded against if the glass is of sufficient strength. A thicker sheet of glass will be far better able to resist stress than a thin one, so it’s often worth going for a 6mm pane over an ordinary 4mm one. When making this decision, however, you should be aware of where the stress is likely coming from. That will depend on how your house is arranged.
In order to reduce the impact of these environmental factors, it’s vital that manufacturers employ environmental controls in their factories. While it’s impossible to eliminate the problem altogether, it is possible to reduce the likelihood of a break to the point of negligibility. A good manufacturer will offer a lengthy guarantee against breakages of this sort – allowing you to shop in confidence.
Heat coming from outside
When it comes to stress on a pane of glass, it’s useful to think not only in terms of quantity, but of concentration. Dispersing heat across the glass will reduce the impact that a concentrated beam of sunlight might have.
In the UK, we experience our sunlight from the south. This means that during winter, south-facing windows are under greater stress. Overnight, the glass will have been cooled to sub-zero temperatures – and then a beam of sunlight will suddenly appear. The centre area will experience a sharp rise in temperature – but for the corners, which are still in shadow, this rise will be much milder. This temperature difference across the glass will place it under much greater stress.
In order to disperse the heat on those cold winter days, it’s worth placing a pale-coloured blind or curtain inside the glass. This will help to reflect heat back onto the glass, helping to more evenly distribute the heat.
Heat coming from inside
Winter is also a time where windows are expected to cope with large changes in temperature from within, as central heating kicks in. The biggest threats to your windows from within come in the form of acute, local thermal shock; typically from a radiator or fireplace right next to your window.
If you’ve got an under-window radiator, then it’s worth providing some protection in the form of curtains which fall behind the radiator, and protecting the window from thermal shock. You’ll also want to ensure that there is adequate airflow to the window from the rest of the room.
Not my work but copied and pasted but it explains what's occurring
