Advice re exterior window protection from breakages

[cherokeev8]

Hi...I have a house where one of the ground floor windows faces the road and has now been smashed on 3 separate occasions either by passing cars flicking up stones or more likely by a tractor with a lawn mower attachment flicking up stones when cutting the grass verge opposite. This is covered by insurance but costs me the excess/inconvenience etc..

Is there anything I can use to prevent the breakages? I was wondering if there is an exterior protective film available? The other option I thought of was to fit an additional acrylic sheet on the outside of the window.

I don't want to fit bars/grilles/shutters etc.

The window is a Upvc double glazed unit with no opening about 1000mm by 1200mm.
Any advice appreciated..............

 

[dishman]

As you say, maybe try some of that perspex sheeting held on by magnetic strips. It is quite cheap, so if it doesn't work, it is no big loss. Do not know how it will react to wind and weather though.

Perspex is very strong and it flexes and is cheap to replace if it does get damaged. With it being attached to the exterior frame there will be a gap between that and the glass giving it a bit of protection and flex space.

 

[3DGuy]

Perspex (Lucite) is good, but I would say on a larger surface area get polycarbonate (Lexan) if you are having windows broken.

See the video below. They use Stones and a Catapult and fire them right at it. The polycarb bounces stones off no problem. Perspex shatters.

http://www.coloradoplastics.com/blog-0/bid/42625/Polycarbonate-Lexan-vs-Acrylic-Lucite

On a window size piece the Perspex will just break every time. I've used Polycarbonate for scopes for combat games, by placing it in front of the lens's and pellets and all sorts have hit this and saved the cost of expensive kit.

You could magnetic it on, or carefully drill a couple of holes in the exterior, and rawl plug those. then just get some rubber washers/gromets on each side of the Polycarbonate then just screw it in. That's probably the route I'd go as I know that plastic is used for Riot shields

 

[TheVictorian]

How about a sealed unit using toughened glass rather than normal glass?

 

[3DGuy]

Isn't toughened glass more for falls against it? that's why its on landing windows and such? Incase tripping on a step. I would have thought it's for low Velocity. A stone coming from the road will be traveling at a fast speed?

Toughened glass is also designed to crumble like car windows to cause less injury rather than break in to shards. I'm not sure it would solve the problem though. Quote below.

"Such stresses cause the glass, when broken, to crumble into small granular chunks instead of splintering into jagged shards. The granular chunks are less likely to cause injury."

Humm, maybe not plug and screw it on, more of a temp fix might be better also. Perhaps two rails where if needed the panel of plastic could be palm slid away in case of emergency exit needed.

 

[TheVictorian]

maybe tempered glass then?

Under wind pressure, tempered glass is approximately four times as strong as annealed glass. It resists breakage by small missiles traveling approximately twice as fast as missiles which break annealed glass. Tempered glass is also able to resist temperature differences (200° F - 300° F) which would cause annealed glass to crack.

Annealed Glass Tempered Glass
Typical Breaking Stress (large light 60 sec. load)
6,000 psi 24,000 psi
Typical Impact Velocity Causing Fracture
(1/4" light 5 gm missile, impact normal to surface)
30 ft/sec 60 ft/sec
[/quote]

 

[3DGuy]

I thought toughened was tempered glass. It's made by heating the surfaces of the glass. There is laminated glass but that can present an exit limitation if you need to get out. The test below is a 5gm missile, I'd have thought a stone that small from a road wouldn't do anything, we have birds fly beak first in to our house windows when they are young and that must have more impact ha!.

Not sure how far the road is to the window? Maybe OP could say.

 

[Gazman16]

Lexan is probably your best bet here.

Tempered/toughened is the same thing its a bit tougher on impact than standard glass but just makes more of a mess when it does break.

Laminated glass too is a bit more resistant to cracking than normal glass but its more of a security/safety thing. Even once cracked you would have a hell of a time breaking in through it.

 

[cherokeev8]

I think I will go down the lexan sheet route...(probably far cheaper I think than any tougher(?) glass than what is already in the d/g unit?)..........
so Fixing with screws will do the job(that bit I can sort out)...however....
***What thickness sheet should I order?****(to save anyone looking above its just over 1m square)...
Once again many thanks for advice thus far.

 

[3DGuy]

I think I will go down the lexan sheet route...(probably far cheaper I think than any tougher(?) glass than what is already in the d/g unit?)..........
so Fixing with screws will do the job(that bit I can sort out)

Yea the polycarbonate is the best way I think.
How far from the road is the window? This might affect thickness of the material. I'd be guessing at 3-5mm.

Screws wise - Just remember if you need to get out of there (not sure the window design) but it will close an escape.

When I picked up mine I got it on ebay actually. Plenty of places sell offcuts and all sorts. If there is not one sized how you need you could send them a message.

I would also put a temp seal on the top/sides. If it rains you don't want dirty rain water getting behind it as it would be a pain to clean.

This ones 4mm - http://www.ebay.co.uk/itm/4MM-LEXAN...t=LH_DefaultDomain_3&var=&hash=item1c2f8d4c81

Thinking about it. I don't know how your windows are but you may actually be able to use a really good quality CLEAR silicone around the window frame. Then just stick the poly carbonate sheet on. This could mean the window could still open easily if needed. A photo of the window would be good

 

[Gazman16]

I would say the thicker the better, Any thickness will protect your glass but thin stuff may end up sounding like your being serenaded by Rolf Harris on a windy day

 

[cherokeev8]

haha....for info its a non opening window so escape is not an issue.....there is an opening window at the other end of the room p0lus French windows

 

[hock79]

Just a suggestion...do you have room for any planting in your front garden? Might provide a barrier to flying stones etc?