What You Need to Know Before Combining Two Apartments in NYC

Perry Hiiman
January 17, 2023
What You Need to Know Before Combining Two Apartments in NYC

Are you considering combining two apartments in NYC? It can be a great way to get more space without buying a new, single large unit. But before you go any further, you should know a few important things about the process and the approvals you need.
From understanding the cost of combination projects and permits that you need from the Department of Buildings to assessing walls for demolition- we’ll walk through all the details for everything you need to know about apartment combinations.

What Are the Benefits of Combining Two Units Instead of Buying One Large One?

Combining two units can be a great way to get more space without buying a large, single unit. This is often more cost-effective since you’ll only have to pay for home remodels and permits once instead of buying an entirely new unit.
Additionally, it gives you the flexibility to design your own space based on the details and layout of both existing apartments. Your home renovation can include custom designs like open-concept kitchens or spacious bedrooms.
These designs would otherwise be impossible with just one large unit.
Plus, most combination projects have long-term benefits such as:

  • Higher resale value
  • Improved property values in your neighborhood

Do NYC Co-op and Condo Boards Approve Combination Requests?

When it comes to NYC co-op and condo boards, the approval process for combination requests can vary significantly.
The board will assess whether the building structure is suitable for a combination project. Once the board does so, they review any necessary permits that you need from the Department of Buildings.
Depending on their decision, they may also ask for proof that you have enough funds. You must have funds to cover the home remodel and fees associated with the project. Other tenants may live in apartments or common areas affected by construction work. Your application in such a case may require special approval from them too.
Every co-op or condo board has its regulations and policies. It’s therefore important to research them before submitting your application. Talking directly with them about any particular concerns or questions is also helpful. This way, you know exactly what to do before starting your home renovation.

Do you need Permits to Combine Two Apartments in NYC?

If you’re planning on combining two apartments in NYC, the first step is to obtain the proper permits from the Department of Buildings. The requirements can make it a complicated process. So, it’s crucial to understand precisely what you’ll need before submitting your application.
The most common type of permit for this project is an Alteration Type 1 Permit. This permit allows you to make structural changes and add new equipment or fixtures. You may also need additional permits depending on the scope of work– such as one for electrical hookups or plumbing installation.
In addition to regular building permits, there are also special considerations when working with co-op and condo boards in NYC.
They may require extra paperwork or approvals that you must complete before starting any home remodels. For example, proof that you have sufficient funds for all associated costs and fees.
Ensure you research these regulations so that the permitting process is smooth. Alternatively, you can work with experienced professionals to help you get the documents.

Apartment Combination Costs in NYC

On average, combining two units in NYC will cost anywhere between $50 – $200 per square foot, depending on various factors. For instance, structural changes like wall removal can make home renovation more expensive.
You should also consider the professional services you’ll need for the project. Although DIY options seem reasonable initially, simple mistakes due to a lack of proper knowledge can be costly.
The best move is to hire experienced professionals, such as NYKB. The experts have extensive experience handling similar projects in NYC. You can rest assured that they’ll do everything correctly and safely without any surprises along the way.

What Department of Buildings (DOB) Rules Do You Need to Know?

When it comes to the Department of Buildings (DOB), you need to know specific rules and regulations before starting your home remodel in NYC. You should understand what type of permit you need for your project and how long it will take to obtain one from the DOB.
You must get special approval from all applicable co-op or condo boards to combine two apartments.
Before applying for a permit with the DOB, consult a professional engineer or architect. The building code compliance specialist should review your drawings, plans, and paperwork.
It will help ensure that everything meets local laws and regulations. You can avoid costly delays due to incorrect documentation.
Don’t forget about additional permits depending on specific features in your project. Some examples are electrical hookups or plumbing installation. These must also comply with strict safety standards set by city and state governments before any work begins.

Is There More Paperwork to Combine Apartments in a Co-op or Condo?

Yes, more paperwork is usually involved when combining apartments in a co-op or condo.
This is because the building’s board of directors must first approve any changes made to the existing floor plan before you can move forward.
In addition to submitting plans and drawings for review, you may also have to provide additional documentation—for example, letters from contractors outlining their proposed work and estimated costs.
Furthermore, depending on the size of your project, you may need to present an impact statement. The statement considers how much noise or disruption the construction works will cause. You may require further approvals from local authorities in such a case.

Expanding into a Building’s Common Space

When considering expanding into a building’s common space, it’s important to understand the rules and regulations of your co-op or condo board. For instance, you should determine how much of the building’s shared space you can utilize for personal use.
Find out details such as:

  • The maximum square footage allowed for each expansion project
  • Any additional fees you may incur during construction

Remember to check for any existing restrictions in place due to fire codes or other safety protocols.
It would help if you also researched the building’s layout to adequately plan where your new space will go within its confines. You should then create a detailed proposal outlining all aspects of your project, including:

  • Estimated costs
  • Materials needed
  • Timelines and more

Lastly, remember any necessary permits, such as plumbing or electrical installations. These processes also require extra paperwork, depending on your intended changes. Instead of dealing with all these complex processes, you can work with experienced professionals who understand all the requirements and procedures.

Differences Between Horizontal and Vertical Apartment Combinations

When it comes to combining apartments, there are two main approaches – vertical and horizontal.
Vertical combinations involve adding a new floor above or below an existing space to create an additional living area. This can be ideal if you’re looking for more square footage but don’t have the budget to purchase another unit outright. However, this option can also be quite disruptive. It involves major structural renovations that may require permission from local authorities.
On the other hand, horizontal combinations involve joining adjacent units together, for example, by removing walls or expanding into common areas such as hallways and closets.
It is less intrusive than vertical expansions and often doesn’t require any extra permits.
However, it comes with challenges, such as ensuring all home remodels meet safety regulations. You’ll also have to coordinate work between multiple owners for everything to go smoothly. Both options offer unique benefits depending on your specific needs. So, consider each before deciding which best suits you.

What Do Architects Consider When Combining Apartments?

Architects must evaluate several factors when combining apartments to ensure the project is successful. Firstly, they consider existing building codes and regulations regarding any changes to the floor plan.
This includes things such as:

  • Fire safety requirements
  • Maximum occupancy levels

The experts also evaluate the structural integrity of each wall or ceiling before making any alterations. It ensures that new load-bearing walls can safely support the weight of additional rooms.
Architects also factor in estimated costs, including:

  • Fees for special permits
  • Materials required for construction works, and many more.

Finally, the architect will create a detailed proposal outlining all aspects of the project. The proposal will include timelines and deadlines. You’ll use this document for the building’s board of directors and local authorities to gain approval before work can begin.

Financing Options for Combining Apartments

Financing for combining apartments can be complex, but the first step is determining how much you need. Generally, this will depend on the size of your project and any additional fees– such as permits or materials and the like.
It’s also important to consider any existing restrictions due to fire codes or other safety protocols. Such limits could significantly impact your budget. Once you have a ballpark figure in mind, it’s time to start looking into financing options available to you.
Depending on your situation, this could include:

  • Personal loans from banks or credit unions
  • Government grants
  • Home equity lines of credit

Ultimately, each option has its advantages and drawbacks. Do thorough research before committing to one financial solution over another.


Combining two apartments into one – whether it’s a co-op, condo, or rent-stabilized unit – can be advantageous in New York City real estate. With a thorough understanding of DOB rules and regulations, the process should be successful.
However, it’s essential to consider all factors involved before taking the plunge. Think of everything from legal requirements and estimated costs to financing options available.
The process can be hectic, especially without any construction background. That’s why Experts from NYKB are ready to work with you. You can count on expert guidance, from the planning and design stage to permits and throughout the home renovation.
Book your free consultation today and let the experts handle all the heavy lifting.

The goal of renovation and remodeling is to ensure satisfaction upon completion of your project. Construction can be very frustrating, and without a professional contractor, things can go wrong.

About Author

Perry Hiiman

Perry Hiiman was born and raised in Tel Aviv, Israel. He planted his roots in Manhatten, New York in 1992. A few years later, Perry met his wife and had three lovely daughters. Perry has always been excited about home improvement and design. He has been in the service industry for over 25 years. Perry and his partner founded New York Kitchen and Bath in 2001. They pioneered the One Stop Shop concept of home improvement and design firms. In addition, Perry is a New York State licensed contractor, OSHA certified, and a New York State licensed mold assessor. He specializes in custom design and is genuinely passionate about what he does—bringing people’s dream projects to life.
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