Installing 350-pound, 10-foot-tall steel fire-rated ceramic glazed lot line windows is no easy feat—especially in a historic TriBeCa building with just five feet of clearance between neighboring structures. When working several stories up, over skylights and alleyways, precision is key. These projects demand careful planning, expertise, and patience to ensure both compliance and craftsmanship.
We recently undertook the replacement of 130-year-old double-hung wood weight and chain windows on White Street—one of our favorite streets in Lower Manhattan, where we’ve worked on numerous projects over the years. Given the building’s age and NYC’s strict building codes, these new single-hung steel windows from Optimum Window were essential. The upgrade ensures compliance with both fire safety regulations and NYC Landmarks Preservation Commission requirements while preserving the historic character of the building.
Why Lot Line Windows Matter
Lot line windows are installed on walls that sit directly along a property line, meaning they must meet fire-rated standards to protect against potential fire spread between closely spaced buildings. These new steel-framed windows provide:
Improved Fire Safety: The ceramic glazing and thermally broken steel frames enhance the fire resistance required for lot line windows.
Sound Attenuation: The DB/OITC-rated glazing significantly reduces noise pollution—a major benefit in New York City.
Energy Efficiency: The insulated steel frames and thick glazing offer better thermal performance, keeping interiors more comfortable year-round.
Preserving History While Enhancing Performance
One of the most rewarding aspects of this project was the careful attention to historical detailing. Custom interior casings were fabricated to match the original woodwork, ensuring that the new windows blend seamlessly into the building’s architectural style.
As this transformation nears completion, it’s clear that upgrading historic windows is more than just an aesthetic choice—it’s a structural and safety necessity. With proper planning, expert craftsmanship, and respect for historical integrity, even the most challenging projects can be executed flawlessly.
