Comiserations – that is a really miserable thing to have happen over the holiday period.
Here is a piece of text I prepared originally for another forum but never posted when the thread degenerated into a load of gun talk.
Section 1
Starting outside in the road the absence of a car in your drive might show you are out, removes the physical block to opening the garage door once that puny lock is broken, and allows a big van to park there hiding the act of breaking the lock and shovelling your stuff straight into the back.
A neighbour might agree to park in your drive when you are on holiday.
Moving to the side gate into the back yard is it easy to climb? Horizontal bars, boards or frames make handy footholds that close vertical boards prevent. Even the hasp and padlock on the outside at waist height are a convenient step. An open top, even at 6ft is no barrier – 8 to 10ft is more like it. A flimsy structure up above the gate may be better than a rigid one that acts as a climbing frame. Having established that glass shards and barbed wire is not legal in some countries get a thorny rose to climb over the frame.
Now walking down the path one of crunchy gravel is off-putting to an intruder trying to keep quiet. However some paving stones are valuable if made to rock by ¼ inch, biased one way. Fit a contact switch (magnetic = waterproof) under the stone and something like a flower pot or kids toy “randomly” on the down end to encourage the intruder to step over onto the tipping end.
Magnetic switches can be placed under pots, toys, and tools that might be kicked aside, or attached to ‘twigs’ sticking out of a bush, all to detect the presence of an intruder before damage is done.
Closer to the shed roses, thorns, pyrocantha and similar shrubs provide barriers to funnel visitors to a protected route.
The shed itself needs to be a bit more than flimsy weatherboard. Outside 4 in mesh ‘hog wire’ stapled every 6 inches holds the boards together making removal more difficult while looking like it was just put there for that thorny rose to climb over. Inside the layers of insulation and lining also add to the difficulty of hacking through the wall. Don’t forget the roof which is often a weak point and if possible go for corrugated iron with some bolts right through inside to big washers.
The window, if you must have one, needs some 2 in weldmesh but then arrange a simple external hinged shutter too. Now we start on the decoys. Make the shutter latch just a toggle, no lock. When opened, a magnetic switch can set the alarm off without any damage having been done. If it had been locked it would have just been another thing to repair without having actually prevented entry.
Now we have got to the door. Not the pathetic panel on so many garden sheds. Build a strong frame and a solid door. If the door opens inwards put a screen door on the outside even if you don’t need it.(that’s a fine mesh door to stop flies that has become less common now we all have aircon). This screen door is another trap having no lock it has to be opened before trying to break the real door – and it sets off the alarm.
If your door opens outwards the screen doesn’t fit so put a simple hinged bar across the door with a padlock hasp. It looks like you fitted it as extra security but forgot to put the padlock on today – move it and off goes that alarm.