Key takeaways
- Commercial is not a grade. Ask for the standard and the grade, such as ANSI/BHMA A156.36 Grade 1, and check it against the maker's spec sheet.
- The function decides how people get out: a single cylinder has a thumbturn inside, and a double cylinder needs a key on both sides.
- On a door people exit through, a deadbolt may be restricted or need conditions, so ask before adding one or changing its function.
- A deadbolt is only as strong as the strike and frame its bolt lands in.
- Measure backset, bore, door thickness and the door and frame material before ordering.
- If the bolt works with the door open and sticks with it closed, look at door and strike alignment first.
First distinction
Grade and duty make a deadbolt commercial, not looks
A deadbolt is a solid bolt you throw with a key or a turn. Unlike a spring latch, it normally stays put when something pushes on its end. A commercial one looks much like a house deadbolt. The differences are the grade it was tested to, the wear it is built for, and whether its cylinder can be keyed into the building's key system. Start with the row that matches your door.
| Your situation | Start with | Who to involve |
|---|---|---|
| New deadbolt on a storage, utility or back-of-house door | Grade, function and the door's measurements | A locksmith, or maintenance staff if the door is already drilled |
| Any door people use to leave a business or a common area | Whether a deadbolt is permitted there at all | A locksmith, before ordering |
| Apartment unit entry door | Whether the deadbolt opens from inside without a key, and the bolt's throw. Codes address both | The owner or manager, with a locksmith |
| Glass and aluminum storefront door | The lock type. These narrow doors usually take a different lock | A locksmith |
| Existing bolt sticks or is stiff | Try it with the door open, then use the problems table below | A locksmith or door technician |
Grades
ANSI/BHMA grades in plain words
Deadbolts are graded under ANSI/BHMA A156.36, the standard for auxiliary locks. The Builders Hardware Manufacturers Association (BHMA) grades hardware 1, 2 or 3, with Grade 1 the highest, and the criteria are specific to each product type. In BHMA's testing under this standard, a Grade 1 dead lock has to survive 250,000 open-and-close cycles and a 1350 pound force on the door against the bolt.
As a working rule, choose Grade 1 for exterior doors and doors that many people lock and unlock every day. Grade 2 can be reasonable on a lightly used interior door.
A grade belongs to the lock as it was tested, and the cylinder type or the strike can be part of that. Read the maker's spec sheet for the exact configuration.
Know the maker? See Schlage commercial deadbolts for that maker's grades, functions and door prep.
Functions
Single cylinder, double cylinder, thumbturn and other functions
The function is what each side of the door can do. It decides how someone inside gets out. Makers use their own names and numbers, so describe a function by what the outside and the inside do.
For doors required to be accessible by the California Building Code, the code says operating devices "shall not require tight grasping, tight pinching or twisting of the wrist to operate." Ask about the turn's shape before ordering for such a door.
The commercial lock functions guide covers how lever locks behave from each side.
| Function | Outside | Inside | Getting out |
|---|---|---|---|
| Single cylinder | Key | Thumbturn | Anyone inside can unlock it without a key. The usual choice where a deadbolt is permitted |
| Double cylinder | Key | Key | Nobody leaves without a key. Can be a life-safety concern on a door people exit through, and the code restricts key-operated locks on many such doors, with exceptions |
| Classroom-style, where the maker offers it | Key locks and unlocks | Turn. Lets people out | People inside can always get out. Whether the inside turn can also lock varies by maker |
Exit doors
Where a deadbolt is a problem: doors people exit through
A separate deadbolt adds a second lock, and while it is locked a second motion to open the door. Building codes limit extra locks and extra motions on exit doors, with exceptions. The text below is from the 2025 California Building Code.
While the deadbolt is locked, a lever latch plus a separate deadbolt takes two motions to open, and a double cylinder deadbolt takes a key from inside. Ask about either one before it goes on a door people leave through.
A fire-rated door carries a label, usually on the hinge edge or the top, and drilling a new lock prep can put that label in question. Don't cut, drill or modify a fire-rated or exit door yourself. That work belongs to a qualified technician.
For the opening as a whole, see the California egress requirements guide and the fire-rated door requirements guide.
| Your door | In plain words | What the code text says |
|---|---|---|
| Doors that are part of the way out of a building | Egress doors must be openable from the egress side without a key or special knowledge or effort, except where the code permits otherwise | "Except as specifically permitted by this section, egress doors shall be readily openable from the egress side without the use of a key or special knowledge or effort." (Section 1010.2) |
| Certain main doors, with a posted sign | A key-operated lock on the inside is permitted, with conditions | In certain occupancy groups, "the main door or doors are permitted to be equipped with key-operated locking devices from the egress side" under listed conditions, including a posted sign reading "THIS DOOR TO REMAIN UNLOCKED WHEN THIS SPACE IS OCCUPIED" (Section 1010.2.4, Item 3) |
| Certain apartment and dwelling doors | A deadbolt that takes a second motion is permitted, with conditions | Certain single exit doors from individual dwelling or sleeping units of Group R occupancies may have "a night latch, dead bolt, manual bolt, or security chain that requires a second releasing motion, provided that such devices are openable from the inside without the use of a key or tool." (Section 1010.2.4, Item 5) |
| Certain doors where the code calls for panic hardware | For certain doors, no latch or lock other than panic or fire exit hardware, with exceptions | Swinging doors serving certain occupancies, including rooms or spaces with an occupant load of 50 or more in a Group A or E occupancy, "shall not be provided with a latch or lock other than panic hardware or fire exit hardware," with listed exceptions (Section 1010.2.8) |
Bolt and frame
Bolt throw, strike and frame, and what to measure before ordering
Throw is how far the bolt projects past the door edge when locked. It is printed on the lock's spec sheet. For the main swinging entry door of a dwelling unit, California Civil Code section 1941.3 gives a figure: the bolt "shall extend a minimum of 13/16 of an inch in length beyond the strike edge of the door and protrude into the doorjamb." The law has exceptions for some existing locks, so ask an attorney how it applies to your property.
Throw only helps if the bolt goes all the way out. On many deadbolts the bolt resists being pushed back only once it is fully extended. A strike hole that is too shallow, off-center or packed with debris stops the bolt short, and the key or turn will not finish its rotation.
In a wood frame, look for a reinforced strike held by long screws that reach the framing behind the jamb. A hollow metal frame needs a reinforced strike prep at the right height, and cutting one into an unprepared frame is technician work.
If the door already has a deadbolt, the easiest replacement is one that fits the existing holes. Measure the door before comparing models.
The commercial strike plates guide and the door frame types guide cover the frame side in more detail. For keying, see the rekey, master key, SFIC and LFIC guide.
| What to record | How | Why it matters |
|---|---|---|
| Backset | From the door edge to the center of the lock hole or cylinder | The bolt has to match it. 2-3/4 inches is the most common backset for cylindrical and mortise locks, though shorter ones exist |
| Face bore | Diameter of the round hole through the door | The standard bored-lock prep for a 1-3/4 inch steel door is a 2-1/8 inch hole. Some deadbolt functions use a smaller one |
| Edge hole and faceplate | The hole in the door edge, and whether the faceplate is square, rounded or absent | The new bolt's faceplate has to cover or fit the existing cutout |
| Door thickness | Across the door edge | Steel door prep standards cover doors 1-3/4 and 1-3/8 inches thick. Thicker doors can need a different kit |
| Door and frame material | Wood, hollow metal, or aluminum and glass | It decides how the lock and strike are prepared and fastened |
| Keys | The key type the building uses, and whether there is a master key | So the new cylinder can be keyed to the existing system |
Alternatives
A deadbolt, a mortise lock with a deadbolt, or an exit device
On a busy door or an exit door, another type of lock often suits the opening better than a separate deadbolt.
Some doors can't take a separate deadbolt at all, as the exit-door section above shows.
See the commercial mortise lock guide and the guide to panic bars and exit devices.
| Hardware | How it locks | Getting out | Often fits |
|---|---|---|---|
| Separate deadbolt above a lever lock | Its own bolt in its own hole | Two motions when the bolt is thrown: the turn, then the lever | Doors where a second motion is permitted |
| Mortise lock with a deadbolt | One lock body in a pocket in the door edge holds a latch and a deadbolt | On many functions the inside lever pulls back both in one motion | Doors prepared for a mortise lock, and heavy use |
| Exit device (panic bar) | A latch released by a push bar across the door | One push | Busy exit doors, and doors where the code calls for panic hardware |
Troubleshooting
Common problems and what they usually point to
Open the door, work the bolt with the key and with the turn, then find your symptom below.
Don't force a stiff key, because keys snap in the cylinder. Don't file the strike hole bigger until you know why the bolt stopped lining up. If the door has sagged, a bigger hole hides the cause.
If the latch is also missing its strike, see why a commercial door won't close or latch.
| What you see | What it usually points to | First check |
|---|---|---|
| Bolt throws fully with the door open, stops short with it closed | The bolt is hitting the strike or frame: a sagging door, a shifted strike, or a shallow or blocked strike hole | Rub marks on the strike and the bolt, and the gaps around the door |
| You have to pull, push or lift the door to lock it | The door has moved off the strike hole. Loose hinges, seal pressure, a closer that does not bring the door fully in, or seasonal movement can all do it | Hinge screws, and whether the door sits evenly in the frame |
| Key is hard to turn, but the thumbturn is easy | The key or the cylinder: a worn key, a poor copy, or dirt or wear in the cylinder | Try an original key, not a copy of a copy |
| Key and thumbturn are both stiff with the door open | The bolt mechanism, or mounting screws tightened unevenly so the lock binds in the door | Whether the lock sits square and snug on the door |
| Key turns freely and the bolt does not move | A broken or disconnected part between the cylinder and the bolt | None. This one needs the lock opened |
Who does what
What to leave to a locksmith, and what to tell them
Tightening loose screws and trying a better key are fair game. These jobs are not:
When you call, say what the door is used for, what it and the frame are made of, any label on the hinge edge, the measurements above, what else is on the door, and what the bolt does with the door open and closed.
- Cutting a new lock or strike prep in a metal door or frame, or in any fire-labeled door or frame
- Adding a deadbolt to an exit door, or changing one from a thumbturn to a key inside
- Keying a new cylinder into the building's key system or master key
- Opening a deadbolt that is jammed in the locked position
- Realigning a door that has sagged or a frame that has moved
If you need a deadbolt fitted or fixed
Elwin Security installs, repairs and replaces commercial deadbolts and door locks for commercial and multifamily properties in the San Francisco Bay Area. Calls are answered 8:00 AM-8:00 PM daily at (408) 539-0535.
Common questions
Questions about commercial deadbolts
What grade should a commercial deadbolt be?
Grade 1 suits exterior and heavily used doors, and Grade 2 can be reasonable on a lightly used interior door. Check the maker's spec sheet for the grade of the exact configuration.
Can I put a deadbolt on an exit door?
It depends on the door. See the exit-door section above for what the code says. Ask before adding one, and don't modify exit hardware yourself.
Is a double cylinder deadbolt allowed on a business door?
It depends on the door, the occupancy and the local code. A double cylinder needs a key to get out, which can be a life-safety concern on a door people exit through. California's code lists conditions for key-operated locking devices on certain main doors, including a posted sign.
Why do I have to pull the door to lock the deadbolt?
Usually because the door has shifted and the bolt no longer lines up with the strike hole. If the bolt works freely with the door open, have the door's alignment looked at before anyone enlarges the strike hole.
How far should a deadbolt's bolt extend?
Far enough to seat fully in the strike. For the main swinging entry door of a dwelling unit, California Civil Code section 1941.3 calls for a minimum of 13/16 of an inch beyond the strike edge of the door, with exceptions for some existing locks. How that law applies to a property is a question for an attorney.
Sources and further reading
These sources back up the general guidance. Your building and the people who approve the work decide the details for your doors.
- Builders Hardware Manufacturers Association: A156.36-2020 Auxiliary Locks (Hardware Highlights)
- Builders Hardware Manufacturers Association: Frequently Asked Questions: product grades
- California Building Standards Commission (published by ICC): 2025 California Building Code, Chapter 10: Means of Egress, Sections 1010.2 through 1010.2.8
- California Legislative Information: California Civil Code, Section 1941.3
- Steel Door Institute: ANSI/SDI A250.14-2025: Hardware Preparation in Steel Doors and Steel Frames
- Steel Door Institute: SDI 135: Guidelines to Measure for Replacement Doors in Existing Frame Openings