Ask Real Estate is a weekly column that answers questions from across the New York region. Submit yours to realestateqa@nytimes.com.

Air-Conditioner in the Way?

I live in a co-op building and have an air-conditioner in my living room window, which is one of two windows that look out onto the fire escape. The air-conditioner does not block access to the fire escape. However, my building manager says city rules prohibit an air-conditioner in a fire escape window. But the Bureau of Fire Prevention told me that I could have one in that window as long as it does not extend out onto the fire escape. Who is correct?

Upper East Side, Manhattan

Memorial Day weekend is the unofficial start of summer, and many New Yorkers will likely spend part of it hoisting unwieldy air-conditioners into their apartment windows. I imagine some of them are eyeing their fire escape windows as a prime location for such an installation. But they should pause, as a fire escape is not an unofficial balcony to be adorned with potted plants or blocked by an air-conditioner. A fire escape is what its name suggests: an escape route for people fleeing or fighting a fire. And it should be free of obstructions. “There should be a focus on safety, fire safety to be specific,” said Joel E. Abramson, a Manhattan real estate lawyer.

The arrangement you described might be permitted by city rules. In general, residents are prohibited from installing air-conditioners in fire escape windows. But they can install one in a fire escape window if the apartment has a second window onto the fire escape that is large enough to be used as an emergency exit. Keep in mind that the alternate window must be large and easily accessible. (A small bathroom window, for example, would not suffice.) The air-conditioner should not extend more than five inches onto the fire escape balcony or obstruct the flow of foot traffic, according to the Department of Housing Preservation and Development. So if the unit you installed blocks the fire escape in any way, it should go. And even if it doesn’t, you still might want to consider a safer alternative.