Window replacement costs in New York

In New York, new windows in a building with three or more apartments come with a child-safety rule attached. The Health Department requires the owner to install approved window guards in any apartment where a child 10 or younger lives, bathroom and public hallway windows included. Windows that open onto a fire escape are left clear. Each guard has to be approved for the type of window it goes on, whether that's double-hung, casement or sliding, and if guards get swapped because of a window replacement, the owner can't charge tenants for the new ones.

If your building is a landmark or sits in a historic district, replacing windows takes a Landmarks Preservation Commission permit. Most repairs don't, and neither do clear glass, caulking or weatherstripping. LPC says most of the replacement proposals it reviews qualify for staff-level approval, provided the new windows match the historic ones closely enough for that facade. The rest go to a public hearing.

Then there's the glass itself. Under the 2025 NYC Energy Conservation Code, which covers Buildings Department filings made on or after March 30, 2026, a replacement window, sash and glazing included, has to meet the code's U-factor limit of 0.27. Storm windows added over existing ones are exempt, as long as the building's energy use doesn't go up.