What Kind of Door Locks Do Building Codes Require?
Locks on exterior doors are what most people think of when considering upgrading the level of security of their homes.

Many people assume their local building codes require a minimum level of quality and security for the door locks installed on their homes. The fact is most building codes don't even require a lock on exterior doors, let alone a minimum level of quality.

This places the selection of the door lock on the homeowner or on his or her contractor. Most contractors are not "lock experts" and they select the locks based on price. That leaves it to the homeowner to either accept the lock their contractor gives them or to select one themselves. The homeowner can make a better selection knowing what to look for and what options are available.

Door Locks From a Burglar's Perspective
A good way to begin door lock selection is to look at it from the burglar's perspective. Burglars prefer to break into a home through a door because it is quick and easy. However, studies have shown that a good quality lock is a deterrent. When intruders are interviewed about the selection of a target, many say seeing quality deadbolt locks on the exterior doors will cause them to move on to another house.

A burglar can enter the home through a door using several methods:

According to a study by the California Crime Technological Research Foundation, the most common techniques used by burglars to enter single-family homes are (from most often used to least often used):

These statistics show how important it is to lock your doors and windows and to install strong door locks. And because most forced entries use some form of impact to break through the door, this means impact resistance should be an important aspect of selecting door locks.

Important Features in Door Locks

1.       Install a Door Lock with a Deadbolt Type Bolt

Every door lock has a bolt that extends from the lock into the strike, which is mounted into or on the doorframe.

The type of bolt has a great effect on the lock's strength. In residential construction there are basically two types of bolts used on exterior doors: latch bolts and deadbolts. Some locks combine the two bolts into one.

The latch bolt is a spring-loaded, bevel-shaped bolt. The spring keeps the latch bolt extended. It will retract by turning the door knob or lever handle. When the door is fully closed, the spring-loaded bolt extends into the strike plate about 1/4" to 1/2."

Latch Bolt

There is also a type of latch bolt called a deadlocking latch bolt which is more difficult to retract when the door is fully closed. The deadlocking latch bolt uses an integral plunger on the face of the bolt that is retracted when the door is closed.

While retracted, the plunger prevents the latch bolt from being retracted by end pressure. These latch bolts are sometimes called pick resistant. However, they typically are no larger in size than a standard latch bolt and they do not extend any farther into the doorframe strike plate than a latch bolt does.

Deadlocking Latch Bolt

A deadbolt, on the other hand, is not spring-loaded nor beveled and must be manually retracted and extended. A deadbolt extends farther into the strike plate than a latch bolt: 3/4" to 1". The deadbolt is rectangular in shape and is larger in section and length than a latch bolt. The deadbolt is manually operated by either a thumb-turn or by key.

Deadbolt

2.       Install a Door Lock with an ANSI Grade 1 Classification

There is a grading system that measures the security and durability of door locks. The American National Standards Institute (ANSI) has standards, developed and maintained by The Builders Hardware Manufacturers Association Inc. (BHMA), that comparatively measure the security and durability performance of door locks.

These ANSI standards, using a variety of tests, classify door locks with a "Grade." Locks that have undergone the testing required by the ANSI standards are given a grade of 1, 2, or 3, with Grade 1 being the best.

Install door locks with an ANSI Grade 1 classification.

There are some confusing details to the ANSI standards that you must be aware of when looking for that Grade 1 door lock. Here are two examples:

a.                   Not all Grade 1 locks are equal. Different types of door locks are tested differently under ANSI standards. But the grade designation system is the same. This means a Grade 1 bored latch set is not tested as rigorously as a Grade 1 deadbolt. The following are the ANSI standards that apply to various types of door lock.

American National Standard for Bored and Preassembled Locks and Latches ANSI/BHMA A156.2

Bored Latch Set

Various Auxiliary Locks: Dropbolt, Rim Lock, & Deadbolt

Interconnected Lock

Mortise Lock

Door locks and latches that fall under the Bored and Pre-assembled Locks and Latches category do not have deadbolts. The door locks covered by the other three standards all have or have an option of having deadbolt type bolts and are all subjected to the Bolt Impact Test. The key here is to get a Grade 1 door lock that has a deadbolt type bolt.

b.       Another important fact to remember is that mortise locks receive both an operational grade and a security grade from ANSI A156.13. The other standards listed above give one ANSI grade classification, a combined performance and security classification. If you choose a mortise type lock, be sure the Grade 1 applies to security aspects of the door lock.

While the ANSI classifications are not a perfect predictor of a lock's performance, they do provide a way to compare one lock to another.

3.       Purchase Door Locks That Offer Key Control

Key control is simply controlling who has copies of keys to your home. Many door keys can be copied at a local hardware or retail store. However, many manufacturers now offer locks using keys that cannot be copied except by certain locksmiths or only by the manufacturer themselves.

There are burglaries where the unlawful entry can be traced back to a key, that was either knowingly or unwittingly provided to the burglar.

Having key control can avoid the following scenarios:

Using locks with key control does not allow anyone to copy keys except you or whomever you designate.

Key control may require extra effort from the homeowner, such as a letter to the lock manufacturer or a trip to the locksmith to get a key made. Also, there is an additional cost due to record keeping by the manufacturer or locksmith (between $10 and $50 per key). The additional cost and inconvenience should be weighed against the security benefits.

4.       Other Door Lock Features to Look For

Security Strike Plate -- A strike plate comes with every door lock. Many times these strike plates are cosmetic and not intended to provide much security. They come with two, short 3/4" or 1" screws to attach it to the doorframe and are made of thin gauge metal.

The strike plate's attachment to the doorframe is usually the weakest point in the entire door/doorframe/lock system.

Standard Strike Plate and Screws

The screw holes are staggered so the screws don't penetrate into the same grain of wood in a wood doorframe or wood wall framing member. The concept of screwing into different wood grains in the doorframe and wall framing is to make it more difficult to split the wood doorframe or wall framing when the door is impacted. This feature should be considered at every exterior door and at those doors coming from attached garages.

Security Strike Plate and Long Screws

The doorframe is spread using a spreader bar. The spreader bar is like a long car jack and is placed between the doorframe. The intention is to spread the frame enough so that the lock bolts no longer extend into the strike plates in the doorframe. If this can be done, the door can be opened while the door is still locked. This feature should be considered at every exterior door and at those doors coming from attached garages.

Saw-Resistant Bolts -- Some deadbolts come with internal anti-saw pins. The pins spin freely inside the bolt. If someone tries to break in by sawing off the deadbolt, the pin will make this difficult because it spins back and forth with every movement of the saw blade.

Don't let double cylinder deadbolts create a fire safety danger to your family.

Double Cylinder Deadbolt

To solve this conflict between family safety and security, one manufacturer has developed a deadbolt lock with a feature called a captured key. On the interior side of the door the deadbolt lock has a thumb turn that can be removed from the lock, leaving a keyhole. The idea is when no one is home, there is no need for the thumb-turn. The last person to leave removes the thumb-turn and creates a double cylinder deadbolt condition.

Captured Key Thumb-turn

Hardened Cased Steel & Beveled Casings -- On a typical deadbolt lock the outside housing of the lock is called the "casing" or "case." Many lock manufacturers make their casings out of hardened steel and many make the casing beveled. The hardened cased steel makes the casing more resilient against blows from a hammer. Beveling the casing makes it very difficult to get pliers or pipe wrenches to stay on the lock when trying to twist it loose.

Dropbolts and Rim Locks -- If a dropbolt or rim lock is selected, make sure the lock is mounted on the door with through bolts.

Dropbolt with Through Bolts and Without

Where to Install Locks With Deadbolts
All exterior doors, including the door between an attached garage and the house, should have a lock with a deadbolt installed. Also, on any doors from the garage to the outside, install deadbolt locks.

Remember, the intruder will select the door that looks easiest to break into and that offers the least chance of being seen. Doors going into the garage and going from an attached garage into the house many times offer an intruder the opportunity to hide from view while they are breaking in. Extra thought should go into the security at these locations.

Additional help can be found . . .
Selecting the right door locks and knowing where to install them is only part of a physical security plan for your home. When considering security at exterior doors, the strength of the door and doorframe are just as important as the strength of the door lock. Read those articles for more information.
Help in assessing the need for better security can be found with your local police department. Many departments have a crime prevention unit that will examine your home. Based on their experience with crime, they can see things that the average homeowner does not. Also, an experienced locksmith can help you select the right products.

¹Appendix X4 of ASTM F476-84 (Reapproved 1991) Standard Test Methods for Security of Swinging Door Assemblies; American Society for Testing and Materials


State Farm® believes the information contained in the Disaster Survival House is reliable and accurate. We cannot, however, guarantee the performance of all items demonstrated or described in all situations. Always consult an experienced contractor or other expert to determine the best application of these ideas or products in your home.

03-05-2001