Any tips on making a intruder-proof grille to cover a window?

[D. Dalton]

I have a window in my workshop that would be very easy to break into. So I am looking to make a grille of some kind that is reasonably inexpensive. It will be fixed to the interior side of the wall. I am considering various ideas, including using steel reinforcement mesh, but have come to the conclusion that I need something that will not just prevent someone breaking the window and climbing in, but also prevent them from reaching in. The window is about 2M x 1.5M. It doesn't have to look posh; it just needs to do the job! I guess it needs to be reasonably bolt-cropper-proof. I guess there is nothing much available that's acetelene torch proof... Any suggestions would be appreciated.

DD

[Nick Odell]

Will it ever need to be used as an emergency exit? Might you have to remove it in a hurry? If so, I would have thought a simple variant on the sort of metal trellis they used to use on old fashioned lift doors would be pretty easy to knock up and effective too. I must admit I'd been thinking along these lines myself and I think it could be doable.

Nick

[fred]

In article , D. Dalton writes

I've done this with Inch weld mesh in an inch angle iron frame which is pretty standard for window grilles. It's a decent deterrent as it would take quite a while to cut enough strands to get in.

You may want an intermediate support for a window that size but I don't think you'll need to go up to 2" angle for the frame.

I cut the angle to the right size for a frame then fixed the weld mesh to is with one inch strip bolted through every 10 inches or so using roofing bolts. The slots were ground off the top of the bolts with an angle grinder to stop them being undone.

You don't need to bolt (or weld) the frame angles together as you gain a lot of rigidity from mesh and strip sandwich.

I had it galvanised and fitted it with M10 coach bolts through the frame.

[D. Dalton]

Nick Odell wrote in news: [e-mail]:

Hi Nick, Thanks for the good suggestion. Actually, the window would never be needed as an emergency exit, as there are two doors on the safe side of the building.

I thought of possibly looking for an old wrought iron (mild steel) gate and fixing that over the window, but it wouldn't stop someone reaching in between the bars.

DD

[Jethro]

Weld the bolts to the frame.

[Jules Richardson]

Hook it up to the mains, and it might :-)

[Nightjar]

It is impossible to make something nobody can get through, so what you need to do is make getting in take a long time, which will deter most thieves, unless you happen to be storing something they really want and can't get elsewhere.

Security cages are generally made from 2" x 2" x 1/8" (50mm x 50mm x

3mm) steel mesh. It is strong enough to need fairly hefty cutters to get through and, even then, it takes a while to cut enough wires to make a hole that is large enough to get through. Using a smaller mesh size and/or thicker wire makes it even harder to get through.

If you want to go for a traditional barred security grill, it should be made of round or square bar, not less than 3/4" (20mm) thick, spaced at no more than 4" (100mm) centres and the bars should pass through and be welded to thick flat strip at no more than 2ft (600mm) intervals. That, again, takes time to cut through and the flat strip stops the bars being opened with a car jack.

Colin Bignell

[Stewart]

My garage has a window like that; it is fitted on the inside with 25mm by approx 4mm bars at 100mm centres, each bar strongly screwed to the window frame. An intruder could break the glass and reach in but could do little more.

[fred]

Only the smooth rounded head visible so can't see the benefit and it screws up the galvanising on both.

[Jeremy Nicoll - news posts]

Bear in mind that 99% of the deterrent value is in making people not try to get in; once someone decides to try they may defeat even quite a strong system. And there's no point in making this strong if eg a door could be forced more easily.

I think I'd try to make something that looks strong, even if it isn't.

[D. Dalton]

Nightjar wrote in news: [e-mail]:

Excellent advice. Thank you! DD

[D. Dalton]

Jeremy Nicoll - news posts wrote in news: [e-mail]:

Actually, that has been my tactic until now, using fake bars. However, now there is increased likelihood of a theft attempt so I want to make it genuinely hard to break into (within reason). There are doors, but not on the exposed side of the building.

DD

[Roberts]

I had a similar problem. I used some thick perspex (or whatever the correct name is ) which I screwed to the inside wooden wall of the workshop. Before doing that I put a piece of patterned glass between the glass and the perspex so I've still got the light coming in but nobody can look in to decide if it is worth brteaking in too. Have a good look around to see if there are any other weak spots. The roof maybe or the doors or are the hinge pins get at able. I can remember getting into a security van in ten minutes by filing off the hinge pin heads and lifting off both doors. The driver had dropped the keys down a drain so it always pays to have a look around your property and think how could I get in. Robbie >

[Jeremy Nicoll - news posts]

You could make it even less inviting with a plywood shark's fin...

[F Murtz]

Grow bougainvillea outside

[root]

Very sound advice. Look up your location on the local crime map. Weigh the likelyhood of a breakin. Design countermeasures accordingly.

Personally, I'd go with just some bent-up rebar bonded to drilled holes in the adjacent wall (on the outside, a deterrent has to be seen before it's encountered) with something like a polyester resin.

In spain it's often mandated for insurance purposes to have "rejas" on all ground-floor windows. Google for the term to get some ideas for more decorative solutions - if it's necessary for the thing to look pretty.

[Reentrant]

Eh? That's frost-tender - I didn't think it survives outdoors here. Did you mean pyracantha? Berberis is another bastard that might help.

[Paul - xxx]

Hook it up to 12v dc, a'la electric sheep/horse/cattle fences and it would deter most people .. simple chicken wire type lattice so they'd need to cut the whole lattice to break the current .. takes time, reasonable deterrent, IMHPOV.