Why's my window exploded?

Woke up this morning to find the none opening bottom part of the downstairs toilet window has gone bang. It’s only the inside obscure glass, the outer pane is still intact. It’s got a lot of cracks in it and a few small pieces had been thrown across the room.

The only thing I can think off is pressure from above but the opening part of the window above has been opening with no problems. The only reason I mention the pressure is that we’ve had new lintels added above a couple of windows as the outer skin only had a soldier course of bricks above the windows. This was fine when the windows were wooden but a few years before we bought the house the wooden windows were replaced with pvc which doesn’t appear to be reinforced. We have one large window at the back where you can clearly see the bend in the frame but that window has held up for over 10 years. It will be getting a lintel for the outer skin when we have the house repointed in a couple of months. There is no sign of any movement or cracks in the soldier course above the window that’s broken so I doubt it is pressure.

Is obscure glass weaker than plain glass and prone to sudden self destruction?

All theories no matter how barking mad would be welcome.

I’d keep an eye out for hora’s son and a bit of duplo.

Toughend is stronger on the face the edge is the weakness. Its possible there is a screw head or a screw coming through from above and the ever so slight movement has caused it to touch the edge pf the glass.

You will see when you come to replace it. Once the beads are taken out look for the culprit 🙂

Water’s got in & frozen, leading to a crack?

My shower screen exploded about 5 summers ago. Our place gets stupidly hot as the sun beats in through the windows all day. Lying on the couch at about 7pm on a Friday night when I heard an almighty bang. Checking the house and I discovered the glass shower screen had completely shattered into little pieces. I can only assume the house was so hot it was causing the walls to shift a bit and it put pressure on the glass.

Did someone leave a very smelly floater overnight 😳

We came back from Christmas one time and found a great big crack in the bedroom window. Letting agents wanted to charge us for a replacement 🙁

Water’s got in & frozen, leading to a crack?

Possible but it’s a window I’ve resealed recently – may be that some water was sealed in and has frozen.

Its possible there is a screw head or a screw coming through

It’on the same wall a couple of meters from a window that’s had a new exterior lintel put in so it could be everything settling back down and as you say it’s easy to break if something is pressing on the edge.
The cracks however run from a large horizontal break out to the edges all around the frame rather than a single point. I’ve got to get the glazers in to change over some glass in a front door so I’ll see what they think when they come and measure up.

UPVC windows aren’t generally sealed, in fact the moisture is designed to run down the sealed unit and drain from various drain holes on the bottom and usually out via the sill. UPVc is reinforced if it’s big enough but that’s more to stop the frame buckling than for it to take any loading.

Sounds like something has shifted.

Window man came round today and say’s it’s almost certainly the weather and he’s already seen 4 others this week that have done exactly the same thing.