Lot Line Windows?

Q: What is a Lot Line Window? Where can I find the DOB guidelines governing Lot Line Windows?

A: Lot Line Windows are windows installed in an Interior Lot Line Wall, meaning in the walls of the building which run along & directly adacent to the side property lines. Walls along the side property line need to be fire rated in accordance with Table 3-4. Windows may, under certain conditions, be installed in Lot Line Walls, with the following restrictions:

1. Lot Line windows are of very limited area (see Table 3-4 & TPPN 10/87)
2. Lot Line Windows cannot serve as required windows for light & ventilation (amenity only).
3. Lot Line Windows must be constructed of wired, tempered, or laminated glass, and must be protected with a Sprinkler Head mounted on the inside of the occupied space.
4. Lot Line Windows must be sealed if an adjacent property owner enlarges their building vertically to block such openings.
5. A Lot Line Window Declaration is required between adjacent property owners.