Grading Your Locks

As you walk down the doorknobs and locks aisle of your local home improvement store, you will probably be bombarded with colorful packaging proclaiming that the hardware contained therein meets “ANSI Grade 3” or “2” or “1”, but what does any of that actually mean?

The answer is, unsurprisingly, not very simple.

First, ANSI is the American National Standards Institute, a private, non-profit organization that helps create voluntary standards for all kinds of things.

Second, the grades you see on door locks and deadbolts are actually a collaboration between ANSI and BHMA – the Builders Hardware Manufacturers Association, whose existence is fairly self-explanatory.

Third and most frustratingly, the standards we are actually interested in – A152.2 for lock-and-handle sets, A156.36 for deadbolts, and A156.5 for lock cores/cylinders – are not freely available online, so I am going to have to reconstruct the details from various manufacturers’ explanation of them.  This information may, naturally, be out of date, so bear with me.

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Background dispensed with, on to the actual nuts and bolts, so to speak.

The grading is set up that “1” meets the highest standards, while “3” meets the lowest, and this is consistent for both locksets and deadbolts.  Furthermore, “Grade 1” is frequently considered “Commercial”, while “2” and “3” are “Residential”; this has no actual bearing on their use or installation, but it may affect how the packaging is branded.

Additionally, the grading depends on what kind of latch or deadbolt specifically we are talking about.  For example, the standards differentiate between a “Patio or Privacy Lock”, which can only be locked or unlocked from one side, and a “Communicating Lock”, which can be locked/unlocked from both sides.  The test standards I list below are the maximums I have been able to find with limited information; it is incumbent upon you to do your own homework.

For bored locks-and-latches / locksets / doorknobs (America generally does not have mortise locks), the following items are tested (per ANSI/BHMA A156.2 “Standards at a Glance” and summaries provided by Sargent and Allegion):

  • Cycles.  A cycle is considered turning the knob/lever all the way to fully retract the latch, and then releasing it.  Grade 1 has to survive 800,000 cycles, 2 has to last 400,000, and 3 only has to meet 200,000.
  • Projection.  If the latch is guarded (meaning it has that funny little semi-cylinder sliding bit on the back of the latch), all grades must extend 0.5 inches.  If it is not guarded, grades 1 and 2 have to extend 0.5 inches, while grade 3 only has to go 0.375 inches.
  • Strike Impact.  Basically, they take a hammer and beat on the lock when it is attached to a closed door.  If the door opens, the lock fails the test.  Grade 1 locks have to survive two strikes of 60 foot-pounds, two strikes of 90 foot-pounds, and two strikes of 120 foot-pounds; grade 2 only has to do the first two tests, and grade 3 only has to do the two 60 foot-pound strikes.  Remember that even if the lock survives, your door frame might not.
  • Strength (Knob).  To receive a grade 1 score, knobs have to withstand 300 pound-feet of torque, 2 only requires 150 pound-feet, and 3 goes down to 120 pound-feet.
  • Strength (Lever).  Naturally, levers have higher numbers, on account of being easier to apply more torque to them.  Grade 1 requires withstanding 700 pound-feet, 2 needs 450 pound-feet, and 3 drops to 225 pound-feet.
  • Finish.  All grades have to survive 96 hours in a salt spray environment.

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For deadbolts, the following items are tested (per ANSI/BHMA A156.36-2010):

  • Cycles.  Basically the same as doorknobs, with grade 1 lasting 250,000 cycles, 2 going 150,000 cycles, and 3 surviving 100,000.  Note that equivalent-graded deadbolts may only last about 30% as long as a doorknob.
  • Projection.  All grades have to stick out a full inch.
  • Strike Impact.  Essentially the same premise as the locksets.  Grade 1 has to withstand two blows of 150 foot-pounds, two blows of 120 foot pounds, two blows of 90 foot-pounds, and two blows of 60 foot-pounds.  Grade 2 only has to do the last three, and grade 1 the last two.
  • Strike Force.  In this case, the testers choose a point one inch from the edge of the door, and on the deadbolt’s centerline (which may be on the deadbolt) and simply apply force.  Grade 1 has to withstand 1350 pounds, 2 takes 1,125 pounds, and 3 only gets 675 pounds.
  • Cylinder Guard Impact.  Basically, the testers rig up a weight at a given distance over the exterior hardware of the deadbolt, and drop it on the mechanism.  In all cases, the lock is withstanding a 75 foot-pound force; grade 1 takes 10 hits, 2 receives five, and 3 only gets two.
  • Cylinder Guard Tension.  In this case, the testers attach a contraption to the lock mechanism that allows them to pull it away from the door, and attempt to pull the mechanism apart or out of the door.  Grade 1 has to withstand a 3,600 foot-pound pull, 2 takes a 2,500 foot-pound pull, and 3 only handles 1,000 foot-pounds.
  • Cylinder Guard Torque.  This time, the testers try to rotate the body / housing of the lock mechanism on the plane of the door.  Grade 1 has to withstand 120 pound-feet, 2 survives 80 pound-feet, and 3 only requires 40 pound-feet.
  • Sawing.  All grades must be able to withstand 5 minutes of sawing on the deadbolt without being able to be pushed open.
  • Finish.  All grades have to withstand 96 hours of a salt spray if they have organic coatings, or 200 hours if they do not; all grades must withstand a 200 hour humidity test; and all grades must withstand a 144-hour-long, 8 hours of UV light at 60 degrees centigrade, 4 hours of condensation at 50 degrees centigrade, alternating test.

Quite a comprehensive list of tests, is it not?  It covers the finish, the strength of the materials, the durability of the entire system, and even how long it will probably last under normal use, much less someone whacking away at it.

But you may also be noticing some glaring omissions as well.  None of the standards I have quoted so far cover anything regarding the various methods used to defeat the actual lock core of deadbolts or doorknobs – picking, picking guns, bumping, drilling, forcing, or anything of the sort.

Unfortunately, that is because all of those standards and requirements are included in ANSI/BHMA A156.5 Cylinders and Input Devices for Locks, and I could not find a copy of that anywhere online.  If anyone has one that they would be willing to share, I will be quite happy to update this post.

In theory, any doorknob or deadbolt that meets Grade 1 requirements for their particular standard must also use a lock core/cylinder that meets Grade 1 requirements for its standard.

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In practice, the reality is a lot less clear-cut:

None of these locks can be considered as high security, but Kwikset, which sells millions of cylinders a year in the U.S., and has incredible market presence, has a grade 1 security rating for its model 980/985 deadbolt, which we selected to analyze. I have attacked Kwikset for several years because of their poor quality and security. In fact, in 2006, the company flew me out to their corporate facility in California for a pre-release briefing of their Smartkey, after eleven-year old JennaLynn bumped open their locks at DefCon. The irony was that senior engineering and management at Kwikset told me that they were not even aware of bumping, except for what they had seen on the Internet! The Smartkey was not designed to be bump-resistant.

At that meeting, I voiced my opinion that the company was selling junk locks. Their reply was “yes, we know, but we make 20-25 million of them a year.” In my view, nothing much has changed in the past four years, other than their locks are mechanically reprogrammable. Clever, yes. Convenient, yes. Secure and maintenance-free, no.

I would strongly recommend reading that whole post, along with anything else on that blog that piques your interest – they actually know what they are talking about.

So what does this mean to you, the end consumer?  ANSI/BHMA grades are unquestionably a good way of determining how durable a specific lock is – a Grade 1 doorknob is tested to last at least four times longer than a Grade 3 doorknob, in terms of daily operation – so if you have children, or are putting hardware in a rental property, the higher cost for the better grade may be worth it.

However, ANSI/BHMA grades are not necessarily a good way of determining how secure a lock is.  For example, the Kwikset Smart Key system is offered at Grade 1 levels, as shown above, but can be successfully – and invisibly – defeated in 10 seconds.

Personally, I would never install any deadbolt less than Grade 1 in my house, or any doorknob less than Grade 2 (oddly, Grade 1 doorknobs are hard to come by), but there are better, significantly more secure (and, unfortunately, expensive) options that we will discuss in future posts.

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9 comments

  1. I consider pick resistance irrelevant to residential grade locks because by and large residential home break ins are not done by picking locks. Picking locks–even a low security five pin cylinder–takes a lot of time to learn and a lot of practice to keep skilled. Locksmiths who spend every day working with locks get good at it, but your average thief doesn’t have the inclination–why should he spend time perfecting a skill so that he can avoid damaging the property that he’s breaking into? It’s faster and easier to break the lock or the door or the frame than to gain entry without damage.

    Lock bumping (or key picking) is a technique that relies on being able to hit the shear line on all pins simultaneously and thus is more effective when used on a master keyed lock (such as you’ll find in a large apartment complex) than on a locked that is factory keyed. (This is because master keyed locks use multiple shear lines on each pin.)

  2. I’m afraid I can’t agree with your summary dismissal of lock picking:

    Especially when factoring in pick guns:

    And, as linked above and here – https://www.youtube.com/watch?v=k1_whuzfB24 – even Kwikset SmartKey locks (about which they are very proud to brag regarding market saturation) and the Schlage competitor – https://www.youtube.com/watch?v=nU9IiVPyNFM – remain succeptible to bumping.

    Furthermore, 30-40%, depending on the specific sample body, of burglaries did not involve forced entry, and this blog has already mentioned one way to help slow actual forced entries, and will talk about others in the future.

  3. The problem is, you don’t get to choose the type of attack a burglar uses. That’s like saying “just get a metal door with a strong door frame. Everyone knows they burglar just kicks the door anyways. You don’t have to worry about thorny bushes around the windows.”

    It’s sounds entirely reasonable to buy better locks if you are replacing them for any reason.

  4. I think Jonathan is specifically talking about locks in this post, and while the entire focus of this blog is on making your home a harder target it isn’t a valid criticism say “well a burglar could go in a window, so don’t worry about the doors.”

    There is no such thing as perfect security, only such a thing as “better” security. And security is really only a measure of time and effort an attacker needs to expend to defeat the security measures in place.

    And I think this blog is a great resource, and I’ll be adding it to my blogroll.

  5. The main goal of the site – that maybe I haven’t done a bang-up job of articulating – is to focus on a single specific topic that many home owners might not think about, but could still help improve the layers of security that protects their homes.

    As I mentioned in the very first post, security is always a matter of layers, and of combined systems, and, yes, it makes total sense to upgrade one’s locks, and upgrade one’s door latches / frames, and add break-resistant film to one’s windows, and so forth and so on.

    But if I write a “complete security solution system” post, it’ll be 20,000 words long, and people will tune out. So I’m trying to go at it a fraction at a time.

    “A fraction at a time” is also a good way of approaching improving one’s home’s security, since some of this is not cheap and might take some time to actually execute.

    In any case, thank you for the kind words, everyone.

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