Fox Police Lock in NYC: Keep It, Fix It or Replace It

The Fox police lock on an old NYC apartment door is a steel bar that braces the door from the inside, and it is still one of the hardest locks to defeat by force. Keep it if the door and the floor are sound. Add a modern keyed deadbolt for locking the apartment when you leave, because a police lock can only be set from the inside.

This post explains what the lock is, why it works, what goes wrong with it, and how to decide between keeping it, repairing it and replacing it.

What a police lock is

A police lock is a bar, not a bolt. The floor-mounted version is a steel bar set at about a 45 degree angle, running from the middle of the door down to a socket in the floor, on the inside of the apartment. A fitting on the door holds one end of the bar and a plate in the floor holds the other.

A second design, the crossbar police lock, uses two steel bars that span the width of the door and extend into brackets set in the doorframe. Unlocking it slides the bars inward until they clear the brackets.

Emiel Fox designed the original, and patents for early versions date to at least 1907. He set up the Fox Police Lock Company in New York City to make them, and the name later became a loose generic for any similar lock. The floor-mounted type was built for wooden doors, and it faded as metal doors and frames became standard. It remains tied to 20th-century New York in a way few other pieces of hardware are, which is why you still see it on prewar doors in Manhattan and the other boroughs.

Why it is still hard to beat

The strength of the design is in the geometry. A regular deadbolt resists one force, a bolt shearing through a strike. A police lock turns a kick or a shoulder into a force that pushes the bar harder into the floor.

To defeat one from outside, the door has to be at least partly destroyed or pulled from its frame, which takes time and noise. That is a different kind of protection from a pick-resistant cylinder: the Fox lock does nothing against a key or a pick, because it has no keyhole. It only matters when you are home.

The limit everyone forgets

A police lock can only be set from the inside. There is no outside keyhole, so it cannot protect the apartment while you are out, and it is the reason nearly every door with one also has a keyed deadbolt.

That means the Fox lock is a second line of defense, a night lock for when you are home. The lock that protects the apartment when you leave is the keyed deadbolt and the cylinder, and that is the lock to upgrade. If the cylinder is a weak one, a restricted keyway is the useful change, covered in do you need high-security locks in NYC.

What goes wrong with them

Four problems come up most often.

The floor socket loosens, because it was often set into old wood and the wood has aged. The fitting on the door works loose from a door that has dried and shrunk. The bar itself is bent or the angle is off after a repainted door shifted. And the door has been replaced or reinforced, so the original positions no longer line up.

Many of these are fit problems, not mechanical failures, and they are fixed by resetting the plate and the fitting into solid material, not by replacing the lock. A door that no longer holds the screws is a different problem, and it is the one described in door reinforcement for NYC apartments.

Keep it, fix it or replace it

Keep it when the door is solid, the floor socket is tight and the bar seats without play. In that case it is doing real work and costs you nothing.

Fix it when the socket or the fitting has loosened. Resetting them in sound material restores the lock, and it is usually far cheaper than any replacement.

Replace it when the door or the floor around it has failed, when the bar no longer fits the door, or when you want a different arrangement. A modern keyed deadbolt on a solid door covers most of what a police lock does for locking up, and a reinforced strike covers much of the rest. For a pre-war door with a mortise lock, the case is often kept and only the cylinder changes, as in pre-war mortise lock repair.

Rules for renters

If you rent, the police lock was almost certainly there before you, and it is part of the apartment. Do not remove it without checking the lease and asking the owner, since it counts as an alteration, and a hole in the floor is a repair the owner may bill.

The reverse also applies. A tenant in a multiple dwelling can add a small lock of their own under Multiple Dwelling Law §51-c, with a duplicate key for the landlord on request, but a floor-mounted bar is not that. It goes into the floor, so ask before you install a new one. For the apartment door as a whole, the code expects a heavy duty deadbolt keyed from outside with a thumb-turn on the inside, which is why a police lock is an addition and not a substitute. The rules on that are in FDNY door lock requirements.

Getting one looked at

If you have a police lock that no longer sits right, the starting point is an inspection of the door, the socket and the fitting. We will tell you whether the existing bar can stay, whether the socket needs resetting, and whether the door itself is the problem.

The keyed lock that goes with it is the part we can improve most. A lock installation or repair visit covers the deadbolt and the strike, and a high-security lock is the upgrade if the cylinder is the weak point. A reproduction of the crossbar type is still made, so a missing or broken one can often be replaced, but we would want to see the door first.

Pairing it with a modern deadbolt

The lock that protects the apartment when you leave is the keyed one, and it deserves the upgrade. A solid deadbolt with a 1 inch throw, a reinforced strike and long screws into the framing covers what the police lock cannot, which is the hours you are out.

Fitting one into a pre-war wooden door takes care. Old doors can be narrow in the stile, the vertical edge where the lock sits, and the thickness may not match modern hardware. That is why a technician looks at the door before choosing the lock, and why a pre-war door sometimes keeps a mortise case and swaps only the cylinder. The comparison between lock types is in understanding different types of locks.

Using it safely

A police lock is a barrier you have to be able to open fast. Everyone in the household should know how to release the bar, in the dark and without thinking, because in a fire it is the last thing between you and the hallway. Do not leave it set when someone is expected home who does not know the routine.

It also helps to keep the area around the floor socket clear. A bar that has to be lifted out of a socket under a rug or a shoe rack is a bar that takes longer to release.

Photograph it before anything changes

If you rent, take photographs of the bar, the door fitting and the floor socket before any work, with the date. A police lock is often original to the apartment, and a photograph is the simplest way to show its condition when you moved in, which helps at the end of a lease if a floor repair is ever raised. The same habit applies to any lock you change, and moving out and the keys and deposit covers it.

Frequently Asked Questions

What is a Fox police lock? A steel bar that braces an apartment door from the inside, usually angled from the door down to a floor socket. Emiel Fox designed the original, with patents dating to at least 1907, and his company made them in New York City.

Is a police lock secure? Against forced entry from outside, yes. To defeat one the door has to be damaged or pulled from its frame. It does nothing when you are not home, because it can only be set from the inside.

Can I lock my apartment from outside with a police lock? No. It has no outside keyhole. You need a keyed deadbolt to lock up when you leave.

Should I remove an old police lock? Only if the door or floor has failed or the lock no longer fits. If it is tight and the door is sound, it is a useful extra layer. Check your lease before removing it, since it counts as an alteration.

Can a police lock be repaired? Usually. Most problems are loose floor sockets or door fittings, and resetting them in solid material restores the lock. A reproduction of the crossbar type is still made if a part is missing.