How to enlarge your living space post Covid: A step-by-step guide for combining two apartments

To combine two apartments is a great way to increase your living space, and in a post COVID NYC there could be more opportunities than we previously had. The market dip has driven down prices, many people have left the city which has increased the availability of apartments and Co-op board rule changes have made them easier to purchase. Buying the next door apartment might be just the solution that you are looking for.

Combining two apartments is not a mathematical operation of A+B = A+B. The challenge is to create, with the same effort and resources, a product that is more than the sum of its parts.

With a growing a family, and the opportunities that the pandemic is creating, this could be viewed as a secure investment for the future while enjoying a larger property NOW…

Victoria Benatar, Co-founder EXD Architecture

To do so, it is important to visualize and understand the space, the needs of the homeowner, the rules of the building, the required permits and to define a budget that makes sense as an investment. In this case study, we talk you through the step-by-step process we followed to enlarge the living space of our client.

Design problem

A couple with a small child lived in apartment A (2 bedroom, 1 ½ bathroom) and had the opportunity to buy apartment B (2 bedroom, 1 bathroom) next door. This also coincided with the pregnancy of the couple’s second child.

Floor plan of 2 apartments before they were combined
Existing separated apartment layout

Solution – how to combine two apartments

The planning and use of the apartments spaces is the key to a great renovation that engages the whole family. It should reflect the homeowner’s needs, but it should also take into consideration the long-term requirements that emerge as life changes, so the efforts and the investment will not become obsolete too soon.

Floor plan to combine two apartments in New York City
Combined apartment plan

How to create multi-functional space and private space?

With the current COVID conditions, it is particularly important to create spaces for a 24 hour day. Activities to consider include lounging, working, entertaining, studying, cooking and exercising, where each member of the family can be sharing space together or having their own space to meditate, work or simply have individual private time. In a lockdown situation, private time in the home has become more important than ever before, and in the future it will surely not be undervalued.

What is the process with the building?

The Alteration Agreement is the document that states the rules, regulations, and procedures for any construction work, whether the building is a Co-op or a Condo. It also indicates what is required to submit for the buildings approvals of the project. Usually, it is a package including a set of architect’s drawings, showing existing and proposed floor plans with the signed alteration agreement, certificate of insurance & workers compensation from the contractor and other submittals.

Depending on the complexity, the board can approve the project or pass it to the building architect for comments and final approval. It is important that the communication occurs between architects (both the buildings and homeowners) who can respond to any questions or objections to the project in the same language. This approval must be received in writing and it can take between 2 weeks to 2 months.

What is the process with the Department of Building (DoB) in NYC?

After the board’s approval, the drawings must be submitted for permits with the NYC department of buildings. This is generally done by an expeditor who will help not only to obtain the permits, but to combine the units in one tax lot and block.

Permits with the city can take one or two months depending on complexity, unless the architect chooses to self certify 1 the project which is faster, but gives the architect more responsibility.

How much will combining apartments cost?

When combining units, it is always very important that the initial investment makes sense for selling the property in the future. The idea is to work creatively with what there is to get the best out of the space and the profit from your investment, so the value of the new unit is much higher than the sum of each individual parts.

What is expected after construction?

After building’s approval, the architect can execute the construction drawings for the contractor’s bid and all material selections. When the city permits are received, the construction work can commence. It is important to understand that no work can be started without the required permits. Again, depending on size and complexity, the construction phase can take between 12-18 months.

At the end of the project, the homeowner will need to get the final sign offs to close out all permits, to legally combine the units into one lot and block.

The result

We successfully merged the two apartments together to create a cohesive 3 bedroom apartment with a layout to meet the needs of the growing family lifestyle. This renovation increased the value of the apartment by at least 30%.

You can read full details of this project here. Let us at EXD Architecture help you envision your new combined space that both allows you to enjoy time together, as well as enjoy a peaceful moment to yourself in New York City!

Photography by Kim Reierson and Styling by Chip Cordell.


We love our work and appreciate the difference it can make to people’s lives. Join us in conversation, at Instagram, Facebook and exdarchitecture.com

Blog written by Victoria Benatar and Michelle Cianfaglione, co-founders of EXD Architecture.


1 (Self-Certification, officially known as Professional Certification, is a process by which licensed professionals may bypass a full review of a building project by the New York City Department of Buildings.)

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