What do locksmiths actually recommend for securing a brownstone in Park Slope?

If you own or rent in a Park Slope brownstone, the honest answer is this: your biggest security vulnerability is almost never the lock itself. It is the door frame. A standard deadbolt on a soft wood jamb with a shallow strike plate can be kicked open in seconds. Fix the frame first, then upgrade the lock. Here is exactly what experienced locksmiths recommend, hardware and all.

What lock hardware actually holds up on a prewar brownstone door?

Prewar brownstone doors are thick and solid, which is an advantage. The problem is that most still have original mortise lock bodies paired with low-security cylinders that any bump key or pick tool can open in under a minute. The mortise lock body itself is worth keeping. It is a robust, full-pocket mechanism that handles the latch and deadbolt in one unit, and replacing it entirely is expensive and unnecessary on a well-maintained door.

What you replace is the cylinder. Upgrade to a Medeco or Mul-T-Lock MT5+ high-security cylinder that threads directly into your existing mortise body. Both are pick-resistant, drill-resistant, and operate on a restricted keyway, meaning keys cannot be cut at a hardware store without your authorization. That last feature, called key control, matters a lot in brownstones where multiple tenants have come and gone over decades.

If your door uses a standard deadbolt rather than a mortise setup, the Schlage B60N is a reliable ANSI Grade 1 deadbolt and a reasonable starting point. Pair it with a Schlage high-security cylinder or swap the cylinder entirely for a Mul-T-Lock or Abloy insert. Abloy uses a rotating disc mechanism with no pins to pick, which makes it one of the most pick-resistant options available at the residential level.

Whatever lock you choose, add a reinforced strike plate with three-inch screws that reach the wall stud, not just the door casing. This single step stops most forced-entry attempts that a deadbolt alone cannot prevent.

When does it make sense to add a smart lock or keypad to a Brooklyn rental or owner-occupied unit?

Smart locks make the most sense in two situations: you manage multiple people coming and going, or you want keyless entry without sacrificing a strong mechanical lock underneath. It depends on your situation, so here are both cases.

If you are a brownstone owner renting out floors in Crown Heights or Williamsburg, a Lockly or August smart deadbolt lets you assign unique codes to each tenant and revoke access instantly without rekeying. August smart deadbolts install over your existing thumb-turn, so you keep the exterior cylinder and your key still works. That matters for insurance and building compliance reasons.

If you want a fully integrated keypad deadbolt with no app dependency, look at the Yale Assure line. Yale builds ANSI Grade 1 hardware, and their locks accept third-party high-security cylinders on the exterior if you want that added layer. The keypad deadbolt handles daily convenience, and the Mul-T-Lock or Medeco cylinder handles security.

One thing to avoid: do not replace a strong mechanical lock entirely with a low-grade smart lock to save money. Several budget smart locks on the market fail basic ANSI grade testing. The lock you see on the door is not always the lock doing the work. Ask your locksmith to confirm the grade rating before any install.

What do locksmiths recommend for storefronts and commercial doors in Brooklyn?

Commercial door security in Brooklyn, especially for storefronts in Bushwick, Bay Ridge, and Brooklyn Heights, involves a different set of concerns than residential work. Foot traffic, employee access, and the sheer weight and size of commercial doors all change what hardware makes sense.

For storefront doors, a jimmy-proof deadbolt or a rim lock with a high-security cylinder is common on metal-frame doors where a traditional mortise is not practical. Jimmy-proof deadbolts interlock with the strike rather than projecting a bolt into it, which makes them much harder to pry open. Pair that with a Mul-T-Lock or Medeco cylinder and you have door security that holds against most attack methods.

For businesses with high after-hours risk, a double cylinder deadbolt on the interior is worth considering. It requires a key to exit, which creates a fire-code obligation, so make sure you understand the commercial egress rules before installing one. Many commercial spaces in Brooklyn pair a double cylinder deadbolt with a panic bar on a second egress door to stay compliant.

Door reinforcement on commercial frames is also non-negotiable. Steel door frames with proper anchoring, heavy-duty hinges with security pins, and a reinforced strike are the foundation. A good cylinder on a weak frame is a false sense of security.

If you manage a loft, co-op, or multi-unit building in Williamsburg or Park Slope and want a professional assessment of your current hardware, call Brooklyn Locksmith & Doors at (347) 357-0985. We handle everything from cylinder upgrades and mortise lock service to full commercial door installs across all Brooklyn neighborhoods.

Frequently asked questions

Is a double cylinder deadbolt legal in Brooklyn apartments?

Double cylinder deadbolts are legal in owner-occupied brownstones but are restricted in NYC rental units under fire code. Tenants must be able to exit without a key. Always check with your landlord and a licensed locksmith before installing one.

What is the difference between a mortise lock and a standard deadbolt?

A mortise lock is a full lock body that fits inside a pocket cut into the door edge, common on prewar Brooklyn doors. It handles both the latch and deadbolt in one unit and is generally stronger than a surface-mounted deadbolt. Most Williamsburg and Park Slope brownstones already have mortise prep built into the door.

Do smart locks work on old Brooklyn doors?

Yes, with the right adapter. August and Lockly smart deadbolts can replace the interior thumb-turn on an existing mortise or deadbolt without touching the exterior. If your door has non-standard prep, a locksmith can fit a new strike and cylinder to make it compatible.