Buying a Deadbolt
Most people choose a deadbolt for its color or finish, but when entry security is paramount, the critical deadbolt feature is its grade. The American National Standards Institute (ANSI) subjects all locks and components to attacks by hammers, saws, wrenches and other tools. Then it grades the lock: Grade 1 (best and toughest), Grade 2 or Grade 3.
Most locks you find in home centers and hardware stores are Grade 2 or 3. Some Grade 2 locks may list Grade 1 components on the package, but that doesn’t give the lock a Grade 1 rating. However, Grade 2 is still a good-quality lock for residential use. We only found one fully compliant Grade 1 deadbolt in local home centers and hardware stores. Professional locksmiths also are a good resource to find Grade 1 deadbolts.
Before you shop for a deadbolt, measure the hole size where the current cylinder fits, as well as the “backset” distance from the center of the cylinder hole to the edge of the door (Photo 1, Step 3). Most new deadbolts require a 2-1/8 in. cylinder hole, but some of them have inserts to fit the smaller 1-1/2 in. hole, so you don’t have to drill to enlarge the hole (Photo 2, Step 3).
The backset distance is usually either 2-3/8 or 2-3/4 in., so make sure the new deadbolt has the identical backset. Most new locks are adjustable to fit either backset dimension. Just read the box carefully (you may have to open it and read the directions to find the information).
Also decide whether to buy a single cylinder (keyed on exterior side of lock only) or a double cylinder deadbolt (keyed on both sides). Check local building codes too, as they may prohibit double cylinder locks for fire safety reasons (it’s more difficult to escape because you must have the key).