Replacing Windows on a Landmark Townhouse in NYC

by | Last updated Jul 23, 2023 | Landmarks, Restoration

New York City Townhouses and Brownstones were mostly built in the mid to late 19th century. Many of these homes, although not all, are Landmarks or in a Landmark District. These homes are well over a hundred years old and often need repairs. One common area of concern is the old windows which often need replacing.


Can You Replace Windows on a Landmark Townhouse in NYC?

You can replace windows on a landmark Townhouse or Brownstone in NYC if you abide by all regulations and obtain approvals from the New York City Landmarks Preservation Commission (LPC). You cannot perform a window replacement without LPC permits. LPC can issue violations for those that do.

All significant renovations and restorations of a landmark Brownstone or Townhouse in NYC must go through the LPC approvals process. This protocol goes for buildings that are individual Landmarks or within a Landmark District.

I am Jorge Fontan, an architect in New York and owner of Fontan Architecture, an architecture firm in Manhattan. At our office, we work on various project types throughout the city, including Landmark Townhouse and Brownstone renovations. In this post, I will discuss some basic concepts for replacing windows in a Landmark Townhouse.

For the purpose of this post, I will not be differentiating between Townhouses and Brownstones, as the requirements are the same. If you want to read about the difference, we have another post on The Difference Between Brownstones and Townhouses.

I also will not differentiate between an individual Landmark and a townhouse in a Landmark District. Both are subject to the review and regulations of the NYC Landmarks Preservation Commission, and the distinction is not pertinent to this article.

Brownstone Windows Before and After

Landmark Brownstone Windows in Manhattan, Before and After


LPC Regulations

The New York City Planning Commission has three categories for Facades on Landmark Buildings:

  • Primary Façade
  • Visible Secondary Façade
  • Non-Visible Secondary Façade


A Primary Façade is the main façade facing the street. The LPC will scrutinize work on a Primary Façade the most.

The visible Secondary Façade is not the main façade facing the front, but portions are still visible from the street. LPC also cares about these facades, but they allow more liberty to alter them.

A Non-Visible Secondary Façade is a building façade not visible from any street. LPC must review and approve all work on a Landmark building, but a Non-Visible Secondary Façade is the easiest one to alter.


Replacing Windows 

The new windows must conform to the character of the building. The most critical issue is that you do not degrade the townhouse’s architecture and do not negatively impact the block’s character.

As an architect, we prepare an extensive photo and written report of the building for LPC. We produce architectural drawings and specifications that we submit to LPC for their review before working on a Landmarked Structure. This process can be time-consuming, but it is necessary. We always advise our clients to be patient; it will take time.


Adding a New Window Opening on a Secondary Façade

As mentioned earlier, you have more freedom with a secondary Façade than a Primary, especially if it is Non-Visible. It may be possible if you want to open the exterior masonry walls and add new windows.

Opening an existing masonry wall will require a structural analysis and structural design. LPC and the NYC Department of Buildings DOB will review this type of work.

Below is a picture of the rear of a Landmark Brownstone we gut renovated. In this Brownstone, we replaced all the existing windows of the house front and back. We also built an addition on the roof, which has its own set of rules. We added new decks and opened the rear exterior walls for new windows and doors. If you want to read about Building An Addition to a Brownstone or Adding a Rear Deck to a Townhouse, we have other posts.

We added sliding glass patio doors to the new deck in this townhouse by breaking through the exterior brick wall. We also installed a new large window to bring light to the parlor floor.

New Window on Townhouse Rear Façade

New Window on Townhouse Rear Façade


One interesting point on this project is that it was relatively easy to get LPC to approve the new window openings on the rear. The window replacement on the front took more time and effort. This difference is because they care far more about the front of the Brownstone than they do the back. But as I said, they still need to review everything. 


Landmark Window Replacement

You can replace windows on a Landmark Brownstone or Townhouse in NYC, but there will be oversight from the Landmarks Planning Commission. You must have approval and permits before you begin any work as per LPC regulations.  

We have another post if you want to read more about Renovating a Townhouse in NYC

Interior of new windows in a Brownstone

Interior of new windows at a Landmark Brownstone in Manhattan


Thank You for Reading Our Blog Post on Landmark Townhouse Window Replacements.

I hope this was helpful. Contact us at Fontan Architecture directly if you want to speak with an architect about a potential project.


Contact Fontan Architecture

Jorge Fontan

Jorge Fontan

This post was written by Jorge Fontan AIA a Registered Architect and owner of New York City architecture firm Fontan Architecture. Jorge Fontan has earned 3 degrees in the study of architecture including two degrees from the City University of New York and a Masters Degree in Advanced Architectural Design from Columbia University. Jorge has a background in construction and has been practicing architecture for 20 years where he has designed renovations and new developments of various building types.