Mechanical and electric door locks are the first line of defense against unwanted entry. Unfortunately, locks can also be the weakest link in your home’s security chain. Skilled burglars can defeat most door locks using readily available tools. By choosing unsophisticated locks for exterior doors or by not protecting your keys, you only make their job easier.
We’ll explain how locks work and detail some new locks that help keep burglars at bay. Some also make changing your locks more convenient.
How Locks Work
Pin-operated locks, by far the most common type, contain a cylinder within a cylinder. Inexpensive models usually feature flat-plate or disk tumbler, while some high-security commercial versions feature two rows of tumblers set at angles to prevent picking.
Notches in the key align the inner cylinders’ spring-loaded pins. Turn the key and both cylinders rotate to operate the bolt. Depending on quality, most residential locks have from three to seven pins, while keys can have up to eight depth-of-cut increments. Since pins of many different lengths can be used in each slot, most locks on the market can accommodate 1,000 to 1 billion possible key combinations.
Choosing a Lock
The best way to gauge a lock’s strength is to check its American National Standards Institute (ANSI) rating, which is typically listed on the packaging. ANSI grades locks on several criteria, including how they hold up against a forced entry and how they resist picking. Grade 1 locks top the list and are designed for high-security commercial use. Grade 2 models deliver the best protection for light commercial or home use. Grade 3 units should be limited to light residential applications such as bedroom or bathroom doors.
In general, choose a Grade 2 knob or lever lock for exterior doors. It should have:
A latch bolt with a 1/2-in. throw that’s built to resist shimming–a way of forcing a lock by inserting a knife in the latch area and pushing the bolt back against the spring.
A cylinder ring that spins. This prevents a burglar from using a large wrench to break off the lock.
Brass cylinders. While most knob locks use zinc, brass units wear longer and are cut to closer tolerances.
Choosing a Deadbolt
When protecting exterior doors, don’t rely solely on a knob or lever lock. For better protection, add a keyed deadbolt. Or you can opt for a lockset that combines a deadbolt and a lever lock. Since a deadbolt doesn’t rely on a spring to keep it in place, the mechanism isn’t easily defeated. When shopping for deadbolts, look for Grade 2 units that have:
A hardened-steel bolt at least 1 in. long. Anything shorter leaves the door vulnerable to kick-in attacks because the bolt penetrates only the jamb and not the framing behind it.
All-metal construction. Intruders can heat up locks and melt the plastic components to defeat the mechanism.
A cylinder ring that spins.
Some Grade 2 deadbolts have benefited from the trickle down of burglar-foiling Grade 1 features. These include bolts fitted with steel inserts to provide extra strength, and bolts with internal ball bearings that discourage burglars from drilling out the lock.
One drawback to adding a deadbolt or installing a new lockset on an exterior door: Unless the upgrade unit is from the same manufacturer as the rest of the locks in your house, you’ll have to add another key to your ring. However, there are several ways around this.
First you can rekey the new lock to fit your existing key. Master Lock’s new Universal Pin system makes it easy for hardware stores and home centers to do this work in less than a minute. Another option is to purchase a Grade 2 Titan deadbolt (or a lockset from Kwikset, Titan’s manufacturer) that offers front-removable cylinders. These allow you to replace the cylinder with one that matches your knob lock and to continue using one key.
While keeping your original keys may be convenient, periodically changing them can be a quick way to boost security. It’s especially important when you move into a house. U-Change Lock Industries lets you do the work yourself Its deadbolts come with three keys and a change tool that allows you to switch between keys. To make the swap, insert the working key and rotate the cylinder 90 degrees. Next slide in the change tool to reset the lock pins. Remove the old key and insert the new one, then pull out the change tool.
Once you return the cylinder to the upright position, only the new key will operate the lock.
On most locksets, you have to work the knob and the deadbolt separately. This can be a problem for older homeowners with declining dexterity, and it can pose a safety problem for anyone trying to make an escape in a fire or other emergency.