Latches and levers
It's worth having a good lock on external doors, but is it worth going over the top? You should definitely augment a nightlatch with a mortice deadlock. You should urgently upgrade any two- or three-lever lever locks to BS3621 five-lever locks, which should cost around £25 to £45 each.
Over the top?
However, very few thieves are likely to pick a lock, so installing a high-security lock that costs nearer £100 needs careful justification. Strong doors or reinforced doors, proper window locks and no ladders, power-tools, etc. on offer in the garden shed, are all more important considerations than going over the top with high-security locks. Many thieves use nothing more sophisticated than a pry-bar, a boot or a spade from the shed.
Walking around here the other day, I spotted a front door with three (three!) high-security locks. Now much as I like my neighbourhood, very few of us around here will attract the calibre of thief who could pick a regular Chubb BS3621 lock, let alone a high-security lock. Still, if a John Robie should stroll by, it's not hard to suspect which house he'd start with. (One of the main reasons you might consider a high-security lock is if its manufacturer guarantees that your keys cannot be copied. Of course that makes the keys expensive to start with, and very expensive to lose. Naturally, we can offer restricted key blanks as well, and they are much less expensive than, say, Banhams.)
Let's think about the night-latch on an external door. You should have a good cylinder, like a Yale, Legge, Union or Chubb. The cylinder is what you can see from the outside; the key turns the cylinder. Cheaper cylinders, like Bird, should only be used on internal doors. Equally important, however, is a) the latch lock on the inside of the door—the latch lock is operated by the cylinder and is what actually houses the bolt, and b) its keep—the keep is on the frame and is what the bolt goes in to. Although it can't really be done, like the movies, with a credit card, a cheap latch can be easily opened by quite simple means. Look to see it your latch has a second, little triangular thingumabob as well as the main bolt.
This prevents the commonest attack. However if the lock has been badly fitted then the device can't do its job. Watch the door close from the inside; note by how much the thingumabob is pushed in. Open the door and push it that much by hand. Now, can you push in the main bolt? If you can then your rimlatch isn't correctly fitted and isn't working. If your rimlatch hasn't got an anti-slip device you should upgrade it.
This isn't the only type of "anti-slip" mechanism. Some locks have an inset in the bolt, and the inset is pushed in by a protrusion in the keep.
Have a look also at the screws and the timber where the latch is fitted. Is the timber sound and do the screws look secure? Consider getting a London bar to help resist a kick; they are not expensive.
Let's think about the mortice lock. Is the mortice (the hole) exactly the right size and is it in the right place? Cheap doors only have one section strong enough to take having a big mortice hole made in it. If the lock's been badly installed or been changed a few times, it's not uncommon to find a too-small lock flapping about in a too-big hole. If the door is less than 44 mm thick then it probably isn't substantial enough that a mortice would increase security rather than decrease it. Can you see any cracks or splits indicating that the door has already been subjected to a hefty kick? If so, you should consider getting lock reinforcement plates fitted; they are not expensive.
And frame and hinge reinforcements are also worth considering.
Locking yourself out
It's quite likely to happen one day. Who has a spare key? Do you know what kind of locks you have so the locksmith can open them more effectively. (Have you got our telephone number in your purse or wallet?) If you have fitted high-security locks, have you got the telephone number of the locksmith that did the installation, or the certificate and the telelphone number of the supplier (e.g. Banham in London).
Planning what you would do if locked out is even more important when you've just moved in. During the first few days, you'll probably have the only copies of the keys, you won't know the neighbours and you'll already be stressed having just suffered the trauma of a move.
Euro and oval profiles
Have you a euro or oval profile cylinder? It's highly likely that you have if your door is uPVC and quite possible on a wooden door. You might want to check whether the installer has done the lock properly; or whether they installed the first lock that came to hand, and left the front face of the lock protruding by a half a centimetre or more. I'm afraid that if they have, you are vulnerable. Call us for more information. I can change to the lock to a more appropriate size in minutes (although the minimum charge is an hour, so between us we might be able to think of a couple more little jobs to fill that hour). If required I can supply a more appropriate lock to the same key as you have now (which does fill up the hour).
If you're a potential customer of mine, then you live in town. If you don't have a front garden, a hedge can give you a sense of privacy and distance from the street. However, it also gives privacy to a thief. If your front door or font windows can't be seen from the street, then a house-breaker can take their time breaking in. Consider trimming the hedge to somewhere between waist height and chest height.
Consider installing motion- or body-heat-activated lights, whether you have a front garden or not.
Around the back
Don't forget that the back door is even more important than the nicely-lit and more-visible front door. Because it needn't be a final exit door, a back door can (and should) be secured with bolts top and bottom. Some insurance companies accept a three-lever lock on a back door, rather than a more secure five-lever lock, provided that key-operated bolts (like rack bolts) are fitted top and bottom. And if there is only one set of bolts on double doors, the bolts should be on the last-closed-first-opened half and should shoot into the frame rather than the other door!)
And don't forget to secure accessible windows and the garden shed. And if you have to leave ladders, crow-bars, spades or other burglariously useful implements in the shed, lock them up within the shed as well as putting good locks on the shed.
We have a page focusing on physical security such as door reinforcment and bars.
You and your insurance policy
I hope all this is useful information for you. However (yes, here comes the disclaimer), you must check your insurance policy to discover exactly what security you are required to fit.
Your own safety
Remember that if it's you who are on the inside, you may want to get out in a hurry. Using a mortice deadbolt, or any lock that might require you to find and operate a key in order to leave in an emergency, could endanger your life. This is even more important if the front door is to a non-ground-floor flat. Your exit-points—especially if there's only one exit-point—should open via a hand-operated turn rather than a key when you are on the inside. (Ask us to fit a fire box near your door, or to fit a thumbturn to a communal door.
Remember, on the other hand that if it's a thief on the inside whilst you are away, you don't want them to be able to open the front door without a key. That way it's more difficult for them to carry away your possessions. If you're sure there's no-one left inside, don't forget to lock the mortice deadbolt.
Naturally, I would welcome your giving me a call to discuss all this.