Hiding a spare key is a great way to ensure youll never be locked out, but the crux of it is hiding the spare somewhere that no one else can find it.
Avoid the Obvious
Ideas you didn't come up with:
Under the doormat
On the ledge above the door
On a window ledge
Front porch flowerpot
Every burglar can spot these and other obvious, overdone hiding spots.
Anywhere within a few paces of your front door should be off-limitsas a hiding spot, for that matter. Burglars won't spend long looking for a spare key, but they will make a quick pass. Your goal is to be clever enough that the burglar decides your house is not worth the effort.
From here, there are different strategies:
Hide your spare keys in something that does not look like a key holder. It should also not look like something thats trying not to look like a key holder: A fake rock or dog turd will probably stand out, unless it looks completely natural.
If you are going to hide your key in a dummy container, choose something less conspicuous. Perhaps this false sprinkler head will do the trick. Or maybe you would prefer the thermometer key caseit actually tells you the temperature, too.
Skip The Key Altogether
Keyless entry garage doors are a great way to make sure you can always get in to your home. You should always lock the door to the house within the garage, but just keep a spare key hidden somewhere inside your garage. This double blind failsafe exemplifies proper security practice, but do remember that if theres a power outage you may be out of luck.
Alternatively, install a combination door lock on one of your doors, and never worry about a spare key again.
Secure The Spare
Keep your spare key in a combination key box or key vault. Mount the box somewhere inconspicuous and away from the door, perhaps inside the electric meter box or similar.
Another variation? Hide your key inside the doghouse, if you have a mean dog.
Somewhere Only You Know
Put the key in a small plastic container, and bury the key in the garden. Just make sure you know exactly where you have buried the keynear a fencepost or between two specific tree rootsso that you dont spend an hour hunting around in the dark, if you find yourself locked out.
Make Velcro Extreme your friend: Stick one side to a key, and affix the backing behind a siding panel, up inside a gutter or somewhere else secret around your house.
Keep a spare key in your car: ideally not in the too-obvious glove box, but rather somewhere sneaky like out of sight inside the trunk, or stashed in a CD case.
Put Your Faith In Your Friends
The surest way to keep the key out of the hands of burglars is to keep your key with a trusted neighbor. Or be extra safe and just give your neighbor a key vault so they have the key, but without access; make it seem less paranoid by offering to hold onto a key vault of theirs as well.
Creative, Discreet And Difficult
When deciding how and where to hide your key, remember that if you can think of hiding it there, a thief can too.
Thus, stow the key so that even if the thief guesses correctly, he cannot get to it; for instance, a key buried beneath a specific backyard rock, or stashed safely in your neighbors kitchen drawer.