Lot line windows - Buyers Beware!

A “lot line window” is a window that is built on a side of a building that shares a boundary line with a neighboring property.  If the adjacent building is built up to or higher than this window, then the lot line window will likely need to be sealed off. For example, Unit 8A has a living room window that faces North. The adjoining property owner on the North builds a 10 story building blocking the windows of Unit 8A. Lot line windows will not affect an owner as an apartment dweller unless your neighbors build up to the level of your apartment or higher.  The concern for a purchaser is that a lot line window that is never disclosed and years later an adjoining building is constructed resulting in the window being permanently closed. In the event such obstruction occurs, the owner would be required to close up the window (usually at the owner’s own trouble and expense), losing both natural light and view.

In new developments, lot line windows are usually disclosed in the offering plan usually under a section entitled “Special Risks” or in the diagram of the apartment in Section II of the offering plan. It is imperative for the buyer’s attorney to review the offering plan to determine if the apartment being purchased has lot line windows. However, older offering plans, frequently do not reflect lot line windows. A purchaser’s attorney should inquire about lot line windows from the building manager. In addition, the attorney may want to check propertyshark.com to check to see if a potential building is proposed on an adjoining property that would affect the purchaser’s windows.

If a purchaser is looking at a listing or an offering plan, rooms with lot line windows are often referred to as “additional living space,” “home office” or “interior office space.” Legally these rooms cannot be called a bedroom. In New York City, a room must have a true (not lot line) window and ventilation to be considered a bedroom. A property with this type of room cannot advertise the property as if the room was a bedroom. If the only window is a lot line window, then legally that space isn’t a bedroom and never was. When purchasing an apartment with lot line windows, it means that the view and light it provides are, in theory, only temporary.

Additionally, if a lot line window has not yet been required to be boarded up, it must meet certain specifications to protect from fires spreading to and from the building. Among the requirements, the window must be made of a fire-rated glass, which is more expensive than normal glass. Also, in some instances, a sprinkler will need to be strategically placed by the window. For this reason, lot line windows are not counted towards light and ventilation requirements.

What most owners/renters of residences with lot line windows may not realize is that these windows aren’t protected and could be lost at any time. The views you now enjoy from that side window could be taken away if a tall building is constructed next door.

Lot Line windows can devalue a property and need to adhere to strict guidelines.

The Lot Line Window Conundrum

The problem with lot line windows is that if a building does eventually get constructed next door, these windows can (and must) get bricked over. The result is loss of sunlight, views, and in the worst case scenario, a bedroom or two. In NYC, for a room to be considered a true bedroom it must have a window. More windows equal more bedrooms. More bedrooms equal a higher value apartment. Windows are serious commodities, which is why unit owners and developers often install lot line windows, even if they may eventually get bricked up by construction next door. It could be years, decades even, before someone builds next door, so you might as well take advantage while you can. BUT, buying an apartment with lot line windows warrants the serious consideration of any potential home buyer.

How Lot Line Windows Can Impact Bedroom Count

If an apartment is being marketed as a 3-bedroom and one of the bedrooms has lot line windows. that room must be re-designated as an office, den, or media room if a building is constructed on that side of the apartment, and the apartment as a whole will officially become a 2-bedroom instead of a 3-bedrooom. When the apartment is sold, the seller will likely have to reduce the price. This is not a rarity.

Assessing an Apartment with Lot Line Windows

If you’re considering buying an apartment with lot line windows you must ask yourself the following:

  1. Does the price reflect the potential loss of bedrooms?
  2. What will happen to the value of the apartment if the lot line windows get bricked over?
  3. Will my family still have enough bedrooms to live comfortably if the lot line windows disappear?

There are a few ways to put your concerns at rest, or at least put them in perspective. When you are looking at an apartment and discover it potentially has a lot line issue, it is vital to look around and get a feel for the neighboring buildings and how they might impact your building in the future. This exercise can help you make good assumptions, ask important questions, and do better research. For example:

Is there an empty lot or a parking lot next door? Empty lots and parking lots are prime targets for future construction sites. If there’s one in your adjacent lot, there’s a good chance that it will be developed in the future. A shorter building that ends below your window line usually has the right to build up. Even if the current owner has no plans for construction, they can always sell it to someone who does.


If a building has lot line windows, it can be very difficult to determine the probability of whether the lot line windows will actually be sealed off.  Signs indicating that an adjacent property may be developed (i.e. vacant, adjoining lots or a rental building) could increase the probability that a lot line window may be sealed off.  An architect or attorney who specializes in zoning and land use should be consulted.

*DISCLAIMER – Nothing herein is offered as legal advice. All information in this article is for informational purposes only. Please consult with an attorney before taking any legal actions.