Guides · 2026-10-08 · 5 min
A master key system for a divided brownstone
How an owner keys the street door, the vestibule and every unit door on one chart, and what to decide before a locksmith starts.
Why a divided house needs a plan
A brownstone cut into apartments has more doors than it looks like from the stoop: a street door, often a vestibule door behind it, a door for each unit, and sometimes a basement or roof door. Over the years these usually get keyed one at a time by whoever was available, so an owner ends up carrying a ring of keys that do not relate to each other.
A master key system puts those doors on one chart. Each tenant has a key that opens the street door, the vestibule and their own unit, and nothing else. The owner or super has a key that opens everything.
What goes on the chart
Before any cylinder is cut, write down every door and who should be able to open it. Tenants share the street door and vestibule, so those two locks take every tenant key. Each unit door takes only that tenant key plus the owner key. Utility rooms and the roof usually take the owner key and perhaps one other.
Ask for the chart in writing. It is the record of which key opens what, and it is what makes the next change cheap: when a tenant leaves, only that unit has to be rekeyed, and the street door and vestibule can stay as they are if the old key is the only one outstanding for that unit.
Questions to ask the locksmith
Can the existing locks be reused, or do the cylinders need replacing? Is the key blank restricted, so copies cannot be cut at any hardware counter? Who keeps the key chart, and how are extra keys ordered later?
More levels on a chart means more flexibility but also a slightly lower margin for error, so a small house is usually better served by a simple layout than a clever one. A fair quote explains the trade-off and gives you a price before work starts.
From Bedford Locksmith, a mobile locksmith and intercom company based in Bed-Stuy, Brooklyn. Questions about your door or entry system? (844) 394-3495.