Toughened windows below what height?

[mfarrow]

4mm of toughened glass is pretty tough, I wouldn't worry about laminating.

 

[cjard]

Given that we have small children is it worth considering laminating the large opening from the outside with laminate glass from both a security perspective but also the realistic assumption that kids will kick balls about or hit them with bars and a laminate glass will take Knocks than regular glass?

Laminated glass is just two sheets of ordinary glass bonded to a sheet of plastic. It can break like ordinary glass, into small splinters and long shards of sharp edges. It tends to stay together - think of the last time you saw a car windscreen smashed. Toughened glass is normal glass whose surface has been cooled faster than standard glass. This creates a tension within the glass pane with the resulting effect that if it suffers sufficient damage in one area the shockwaves/release of tension cause the entire pane to disintegrate instantly into small cubes - think of the last time you saw a vandalised busstop or phone box. This can result in more spectacular breaks than a standard pane though injury is less likely to result.

If I had windows that kids were routinely going to be kicking a football against, I'd make them toughened rather than laminated for safety reasons rather than breakage reasons - a football is very unlikely to break a toughened pane. They'd also get something between a rollicking and a thick ear. If they were going to be hitting the windows with bars, nails, sticks etc that's kinda a completely different disciplinary matter starting at thick ear

 

[JohnD]

I use laminated glass for burglar resistance, toughened is very easy to break and walk through.

 

[ey143]

Cjard,
Good points but laminate surely will be better because if it breaks, the glass will remain intact and just have a spider web effect. Don't a lot of American movies show a a person flying into the windscreen creating a spider effect and the driver trying to kick the glass out from behind at 100mph because he can't see?! Point being that the glass is intact compared to shattering like the bus stop / phone box ones?

I was told it's useful for when you have a breakage in say a roof lantern or something so that you don't need emergency glazing on Xmas day as the inside glass remains undamaged? Also as johnD mentions, makes it that bit harder for burglars.

 

[cjard]

Mmmh, in a windscreen, punching a broken windshield out at 100mph probably gets you a cut and broken hand, and a face full of glass tiny splinters regardless of the fact that the sheet for the most part remains windscreen shaped. Remember; a laminated pane will still shed razor sharp, tiny bits of broken glass as it crazes

For your roof lantern, it's probably a composite double glazed panel with one pane being toughened and one being laminated, the inner one being the laminated one. Interestingly, here's the BRE test of the roof glazing system I ended up using, a 50kg sack of glass beads being dropped on the windows from 2.4m high..

 

[ey143]

Just to come back to this subject - if I am more concerned about security and planned to laminate the glass, will this get around the problem of not toughening them below 800mm height?

 

[cjard]

Yes, laminated glass is classified as safety glazing for this application

 

[u587162]

But would that need to be laminated on both sides or is one (external) side enough as I believe double glazing firms only do the external side.

 

[cjard]

Both panes, I believe (if they're both within the relevant zone.. e.g. no requirement to safety glaze a window outer pane that is 2 metres up a wall because there's noone generally floating around mid air to break it and damage themselves on it. The inner pane is the one that would need to be safety glazed if it were within 800 of the bedroom floor)