A function code says what the lock does from each side
A lock function code, set out in ANSI/BHMA A156.2, describes how the lock behaves from the outside and from the inside. Two locks that look identical on the door can carry different codes and behave completely differently.
The code, not the brand, decides whether the door secures itself behind you, whether a key is needed from outside, and whether the inside can be locked at all. It is the detail most often got wrong on a replacement, because the person ordering describes the lever instead of the behaviour. On almost every commercial function the inside lever is always free, so anyone can leave without a key or a code.
The usual answer by door type
Conventional pairings on existing commercial openings, not a specification for your building.
| Door | Usual function | Why |
|---|---|---|
| Corridor or interior office door | F75 passage | It needs to latch and stay shut. Security sits at the suite door. |
| Restroom | F76 privacy | Locked by the occupant, released from outside without a key. |
| Exterior entrance | F86 storeroom | Secures itself on closing, so nobody has to remember to lock it. |
| Classroom | F84 classroom, or classroom security | Locking is held at key level. Classroom security adds a keyed inside cylinder for lockdown. |
| Storeroom, closet or mechanical room | F86 storeroom | Entry by key only, and it cannot be left on the latch by accident. |
| Janitor closet | F86 storeroom | Same reason, and it keeps chemicals and plant behind a locked door. |
| Stairwell door | F86 storeroom, or a listed stairwell function | The egress side is always free. Re entry from the stair depends on the building, and some stairwells require controlled re entry hardware. |
We sell listed hardware and confirm the specification in writing. We are not code consultants; your Authority Having Jurisdiction (AHJ) makes the final call.
Six details decide the part number
- Function. What the lock should do from each side. If you are unsure, describe what should happen when the door closes behind you.
- Backset. Door edge to the centre of the bore, commonly 2 3/4 inch on commercial doors, 2 3/8 inch on lighter ones. It has to match the prep already in the door.
- Door thickness. Standard commercial doors are 1 3/4 inch. Anything else changes the part number or needs a spindle kit.
- Finish. 626 satin chrome is the default on commercial locks, with 613 oil rubbed bronze and 693 black common alternates. See the finish code chart.
- Handing. Read from the outside, meaning the keyed side. Many exit trims and keyed cylinders are handed at the factory and cannot be reversed on site. See the door handing chart.
- Keying. Keyed alike across a group, or keyed to an existing system, has to be told to us before the order is placed. Cut keys cannot be returned.
Handed and keyed items ship only after you confirm handing, finish and keying in writing. Everything else ships the same or next business day.
Send a photo of the lock and the door
The lever, the inside of the door and the door edge are usually enough to read the function, the backset and the handing. You get part number, grade, finish, price and lead time back the same business day.