What Causes Sliding Glass Doors To Spontaneously Shatter, And How Can You Prevent It?
While it's a relatively rare problem, sliding glass doors are capable of spontaneously shattering. Sliding glass doors are made of tempered glass, which allows small chips to rapidly spread throughout the entire pane, causing it to crumble apart.
A shattering glass door is rarely dangerous, but it can be a disconcerting experience when it happens to you—it often sounds like an explosion went off in your home. Here's what you need to know about why sliding glass doors can spontaneously shatter and how you can prevent it.
Why Do Sliding Glass Doors Spontaneously Shatter?
Sliding glass doors (unless they are very old) are made of tempered glass. When tempered glass is produced, it's heated to extreme temperatures and then quenched in order to quickly cool it down. The quenching process causes the outside of the tempered glass pane to cool more quickly than the inner core, and this temperature difference causes the outside of the glass pane and the core to slightly pull away from each other.
When the outside and the core pull away from each other, it puts the entire pane of glass under a significant amount of tension, and this tension is what makes tempered glass stronger than older annealed glass. It's also the reason why tempered glass breaks into small rounded granules instead of sharp glass shards, making it safer to use in a sliding glass door.
Unfortunately, this tension is also the reason why tempered glass can spontaneously break apart. Any small chips in the glass—especially at the edges—will rapidly cause the entire pane of glass to crack apart due to the extreme tension it's under.
The root cause behind a sliding glass door that spontaneously shatters, therefore, is a small chip that rapidly spreads due to the properties of tempered glass.
What Causes Sliding Glass Doors to Form These Tiny Chips?
Most cases of spontaneous glass shattering tend to be blamed on impacts. This is actually fairly rare—tempered glass is quite strong and can easily withstand wind-blown debris and other common causes of impacts to a sliding glass door. However, impacts to the very edge of the glass pane are capable of creating a chip that will eventually result in the pane shattering spontaneously.
Instead, spontaneous glass shattering often occurs simply due to manufacturer error. If the pane of glass within the sliding glass door isn't properly cushioned against the metal frame, it can eventually develop chips around the edges from repeated impacts. If your sliding glass door is difficult to open and close, causing you to slam it shut whenever you close it, then these chips are more likely to form.
Temperature changes can also result in chips forming around the edges of the pain. This is due to thermal expansion and contraction along with the relative rates of how quickly different types of materials expand. The metal frame of a sliding glass door is a conductor, so it expands more quickly when exposed to sunlight compared to the drywall and siding that encase the metal frame. This results in a small amount of tension as the glass pane and its metal frame push against its enclosure. Tension can cause stress fractures to form around the edges of the pain, eventually leading it to spontaneously shatter.
How Can You Prevent a Sliding Glass Door From Spontaneously Shattering?
You can't do much about manufacturer error or the weather outside, but you can prevent a glass door from spontaneously shattering by regularly inspecting it. Wait until it's dark out, then use a small flashlight to carefully inspect the edges of the pane. Look for any tiny chips along the edges that can eventually spread and cause the entire pane to shatter.
If you notice any chips, have your sliding glass door inspected by a residential glass contractor. You may have to replace the pane of glass in order to reduce the risk of it spontaneously shattering. Residential glass professionals can often tell you the reason why these chips are forming—if it's due to manufacturer error and chips are forming because the glass is constantly rubbing against its metal frame, you may want to replace the sliding glass door entirely in order to reduce the risk of it shattering.
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