Heavy and expensive is not the same as high security
A solid brass deadbolt that weighs a pound and costs a lot can still open to a cheap copied key. Weight, finish and price tell you nothing about what is going on inside the cylinder, which is where most of the real security lives.
A true high security deadbolt is defined by test results and key rules, not by feel. When we assess a lock, we look at three separate layers, and a weak link in any one of them undoes the other two.
| Layer | What it protects against | What to look for |
|---|---|---|
| Hardware | Bolt and housing failing under force or heavy use | ANSI/BHMA A156.36 Grade 1, or A156.40 AAA on residential models |
| Cylinder | Picking, bumping, drilling and forcing the keyway | A UL 437 listing for the exact cylinder; BHMA's A156.30 covers high security cylinders |
| Keys | Unauthorized copies by anyone who borrows a key | A restricted or patented keyway with documented authorization |
Layer one: hardware that survives force and wear
The bolt, housing and mounting have to hold before the cylinder even matters. BHMA's public summary of A156.36 says Grade 1 deadlocks must pass 250,000 cycles and seven security tests, one of which puts 1,350 lb of force on the door against the bolt.
Residential deadbolts can instead carry A156.40 letter ratings, where AAA is the top rating for security, durability and finish. Some models carry both. How those two scales differ is a topic of its own, covered in our guide to deadbolt grades.
Here is the trap: a Grade 1 or AAA rating describes the hardware, not necessarily the cylinder or the key. Schlage's B600 is a Grade 1 commercial deadbolt, but it is UL 437 listed only when fitted with a Primus UL 437 cylinder. Order it with a standard cylinder and you have strong hardware with an ordinary keyway.
Layer two: a cylinder tested against picking and drilling
UL 437 is the listing most people mean when they say high security. According to a distributor's summary of the standard, it tests a cylinder against picking, drilling and forced entry, such as a tool driven into the keyway and turned, for a minimum set time under lab conditions.
At Deadbolt Fixers, we do not quote attack times. The standard is paywalled, and the numbers repeated online do not agree with each other. What matters to you is whether the specific cylinder on your door is listed.
What resistance looks like inside the cylinder
Manufacturers get there in different ways. Schlage describes its Primus cylinders as using hardened steel and anti-drill pins, plus a second, independent sidebar and finger-pin mechanism that protects against picking and bumping. Mul-T-Lock lists UL 437 and ANSI Grade 1 conformance for its Hercular deadbolt, which has a standard 1" bolt throw.
Layer three: key control and restricted keyways
A pick-resistant cylinder does little if anyone who borrows your key for an afternoon can get a copy cut. Key control closes that gap. On a restricted or patented keyway, blanks are not sold openly, so copies come only through authorized channels.
Schlage says its Primus keys are tightly controlled, with factory-milled side bitting designed to make unauthorized duplication hard. Its Everest 29 system is patent protected through 2029, and the company states those keys cannot be duplicated without authorization.
Key control is also a habit. Schlage's Everest 29 manual advises a written policy naming who may authorize new keys. For a household, that can be as simple as one person holding the authorization and a short list of who has keys. For a business with staff turnover, our page on deadbolts for storefronts and offices goes further into managing keys across a team.
A restricted keyway also changes servicing. A standard cylinder can be rekeyed at almost any locksmith shop, but a controlled system usually needs authorized parts, so it is worth knowing who can rekey the lock later before you commit to a system.
Doors that justify a high security deadbolt
Not every door needs this level of hardware. These are the situations where we recommend it.
A high security deadbolt is worth it when
- Keys have been lost, or copies may be circulating that you cannot account for
- Many people need keys: tenants, staff, cleaners, contractors, family members
- The door protects high-value equipment, inventory, records or a home office
- The door is out of sight from the street, giving someone time to work on the lock undisturbed
- You already have a strong door, frame and strike, and the cylinder is now the weakest point
The last item matters. A high security deadbolt on a hollow door with a strike held by short screws spends money in the wrong place. BHMA itself notes that lab results can differ in the field depending on installation, door and frame construction.
The rest of the door has to keep up
Pick and drill resistance protect the cylinder. They do nothing for the jamb. A kick-in attacks the strike, so every high security deadbolt we fit gets checked against a reinforced strike plate with long screws, and we recommend that upgrade wherever the existing strike is thin or poorly anchored.
The same logic applies to smart locks. Consumer Reports notes that a retrofit smart lock's kick, pick and drill resistance depends entirely on the deadbolt it is paired with. If you want app control and serious resistance, the deadbolt underneath has to be the high security part. Our smart deadbolt installation page covers which approach fits which door.
What a high security deadbolt visit covers
On site, we confirm the door thickness and backset, check the frame and strike, and walk you through the key system options that fit your lock. If you are upgrading an existing Schlage Everest or Classic system, Schlage offers Primus cylinders as an upgrade path to regain key control, which can save replacing every lock on the system.
Price depends on the hardware, the cylinder type, how many locks share the key system and how many controlled keys you need. The deadbolt installation cost guide explains how those factors turn into a quote.
Field tip: look the lock up before you buy it
Write down the exact model number, not just the brand, and search it in BHMA's free Certified Products Directory to confirm the grade. Then check the manufacturer's spec sheet for the words "UL 437 listed" next to the cylinder you are ordering.
Finally, ask the seller one question: who can authorize a copy of this key? If the answer is "anyone with the blank," you are not buying a high security deadbolt, whatever the packaging says.
Next step
Talk to a Deadbolt Fixers specialist
Tell us about the door, the lock and what is going wrong. We will tell you what the job involves before any work starts.
Frequently asked questions
What makes a deadbolt high security?
A cylinder tested and listed for pick, drill and force resistance, usually to UL 437, combined with top-rated hardware and keys that cannot be copied without authorization. Missing any one of the three leaves an obvious weak point.
What does UL 437 listed mean on a deadbolt?
It means the cylinder passed UL's lab tests against picking, drilling and forced attacks for a set minimum time. Check whether the listing covers the cylinder you are actually buying, since some deadbolts are listed only with a specific cylinder.
Do high security deadbolts fit standard residential doors?
Many do. Mul-T-Lock's Hercular, for example, has a standard 1" throw and suits two backsets without extra parts, while commercial models such as Schlage's B600 are built for thicker 1-5/8" to 2" doors, so we check the door before ordering.
Can high security keys be copied at a hardware store?
Not on a properly controlled system. Schlage says its Primus keys are tightly controlled with factory-milled side bitting, and its Everest 29 keys cannot be duplicated without authorization.
Who can rekey a high security deadbolt?
Usually a locksmith with access to that key system's authorized blanks and parts, and on some systems only through the dealer or the system owner. Ask about this before you buy, so you know who can service the lock later.
Can I add a high security cylinder to my existing deadbolt?
Sometimes. Schlage's Primus cylinders, for example, are offered as an upgrade for older Schlage Everest and Classic systems, but compatibility depends on the brand and model of your current lock.
Do high security deadbolts resist lock bumping?
Good ones are built to. Schlage's Primus design adds a second, independent sidebar and finger-pin mechanism specifically to protect against picking and bumping.
How long does a UL 437 cylinder resist attack?
UL 437 tests for a minimum set time under lab conditions, but the standard is paywalled and the figures quoted online disagree, so we do not quote times. Treat the listing as proof of tested resistance, not a countdown.
What is BHMA A156.30?
It is the ANSI/BHMA standard for high security cylinders, with a 2025 edition listed by BHMA. It sits alongside UL 437 as a reference point when a manufacturer describes a cylinder as high security.
What is a restricted keyway?
It is a key profile that is not sold as an open blank, so copies come only through authorized channels. That is what stops an ex-tenant or contractor making a duplicate at any key counter.
Is a high security deadbolt worth it for an ordinary house?
It is worth it when keys are hard to account for or the door guards something valuable, and less so when the frame and strike are still weak. Fix the door and strike first, then upgrade the cylinder if copied keys or picking are your real concern.
What does drill resistant mean on a lock?
It means hardened parts placed to defeat a drill bit before it reaches the pins. Schlage, for example, describes hardened steel and anti-drill pins in its UL 437 listed Primus cylinders.
Which brands make UL 437 listed deadbolts?
Several do, including Schlage (Primus cylinders and the B600 with a Primus cylinder) and Mul-T-Lock, whose Hercular deadbolt lists UL 437. Always check the specific model's listing rather than the brand name.