Field notes · 2026-08-19 · 6 min
Securing a Brooklyn brownstone door without ruining it
What actually protects a 100-year-old rowhouse door — and what just puts holes in irreplaceable wood.
The door is the asset — treat it that way
A Park Slope brownstone door is often original to the house, which makes it both the most attractive thing on the block and the most expensive thing to replace. Every security decision should start from one rule: improve what the lock does without changing what the door is.
That rules out most big-box 'smart lock kits', which are designed for modern 1-3/8" slab doors and leave oversized bores in antique wood when they inevitably come off.
Upgrade the cylinder, keep the mortise
Most pre-war doors run a mortise lock — a rectangular case set into the door edge. The case is usually fine after a century; the cylinder is the weak point. A high-security cylinder (Medeco, Mul-T-Lock, Abloy) retrofits into the existing case, adds pick, bump and drill resistance, and restricts key copying — with zero visible change to the door.
The vestibule is a system, not two random doors
Rowhouses run an outer and inner door in series. Key them alike so one key runs both, and put the high-security money on the inner door — the outer door's glass makes it a delay, not a barrier. A reinforced strike plate with 3" screws into the frame stud does more than a second deadbolt.
What we'd skip
Bar locks and surface-mounted jimmy-proof locks have their place on service doors, but on a landmark-grade front door they solve a problem the mortise upgrade already solved — while advertising fear from the street. Spend on the cylinder, the strike, and the frame.
Written by President Locksmith & Security — a working locksmith dispatching from Park Slope, Brooklyn. Questions about your door? (646) 832-4007.