How Much Does a New Jersey Home Addition Cost?

UPDATED: January 7, 2025

Adding a room or addition to your home in New Jersey offers alternatives to building or buying a new home. On average, homeowners in New Jersey spend $48,000 adding additional living space to their existing homes. Of course, many variables affect this number. Material costs, labor costs, local building requirements, and your location all factor into the equation

The average cost for an addition in New Jersey is $126,000, and it costs $227 per square foot. Homeowners spend an average of $95,500 for a bedroom addition in New Jersey, $146,980 for a master suite addition, and $68,500 for a bathroom addition. You can expect to spend $85,800 for a garage addition in New Jersey and $43,917 for a front porch addition.

Cost Considerations When Adding on to Your Home

Many variables contribute to the average cost per square foot of an addition to your existing home. One of the most important variables to consider is the type of addition you are planning. Some of the most popular additions to existing homes include:

• Bedrooms
• Master bedroom suites
• Bathrooms
• In-law apartments
• Family rooms
• Detached garage
• Sunporch

Other variables that can affect the overall cost of an addition to an existing home to consider when planning are

• Location
• Local building requirements
• Style and quality of construction
• Labor costs in your area
• Materials costs

There is no doubt that an addition to your home can add value over the long run. There is also the risk that you may overbuild for your neighborhood which can, surprisingly, cost you money. Looking at some of these home addition projects may help you as you plan your project.

The Cost Per Square Foot for Home Additions

It is hard to make an initial estimate of the cost per square foot for even the simplest home addition in many instances. So many variables enter the equation the minimums and maximum costs are widely separated. As we have mentioned earlier, in New Jersey, the cost for the average home addition varies by a large amount

Average Cost of a Home Addition in New Jersey

The Formula – Calculating Home Addition Costs in New Jersey

When making estimates on the cost of an addition to your home in New Jersey, it is important to understand that you are performing rough calculations. Such rough calculations don’t factor in many of the variables that can affect cost. It is always preferable to calculate a range of costs and wait for your contractor or builder to give you an exact cost estimate for the project.

In general, you can figure the range of costs to complete a home addition in New Jersey-based on these figures. We based these numbers on an average high and low cost of $176 and $328 per square foot.

Home Addition Costs by Square Foot

Average Size Room Addition Costs

The cost to add a room to your existing home can vary greatly depending on the function of the room and the quality of the materials and fixtures you choose. On average, a simple bedroom addition costs much less than the addition of a bathroom or a master bedroom with an ensuite bathroom.

Start with the cost of adding basic space to your home based on the square footage of the physical space. You can then add other costs based on the function, use, and style of the addition. We use $227 per square foot to calculate this construction cost.

Basic Room Addition Cost (per square foot)

Functional Home Addition Costs

On top of the basic costs of adding floor space to your existing home is the functional costs. Each room function incurs additional costs. Bathrooms require plumbing and fixtures. Kitchens require plumbing, extra electrical, special cabinetry, and appliances. The following chart will help you when estimating the costs of your home addition

Room Function Cost Calculator

NOTE: These figures reflect the rapid inflation of the cost of building materials and supplies over the last 12 to 18 months. In some cases, the cost of lumber has increased by 180% during this period.

The Basic Bedroom Addition

The cost of adding a bedroom space to an existing home in New Jersey is between $140 and $257 per square foot. Consequently, the addition of a 12 x 12-foot bedroom to the side of an existing home is between $20,160 and $37,008.

This estimate is for a basic room addition that meets most local building codes. Many other variables can add additional costs to any room addition, such as:

• Premium trim and millwork
• Upgraded floor coverings
• Costs to match the existing siding and roof of the home
• Extra windows or other exterior openings
• Additional framing and finishing costs for closets or built-ins
• Upgraded lighting and accessories

Master Suite Additions

Adding a new master suite to your home can be a game-changer for both you and the value of your home. Many older homes don’t include an ensuite bath in the original master bedroom. Creating a new private space with all the most modern amenities can create a completely new feel for your home.

Typically, a new master suite addition has more square footage than the original master bedroom and more closet space. Adding an ensuite bathroom creates an even more luxurious feel. Unfortunately, all these additions and amenities increase costs for the addition as well.

The average new master suite addition to existing homes in New Jersey is close to 500 square feet. This additional square footage of a larger bedroom, the ensuite bathroom and additional closet space can cost between $106,920 – $173,700.

Of course, the top end of this range is by no means the cap. The addition of expensive amenities such as saunas, a small kitchenette, or even a swim spa can drive the cost even higher.

Bathrooms – To Add or Remodel?

Many homeowners consider the question of adding a new bathroom or remodeling an existing bathroom. Both are viable options but come at much different costs. Typically, a bathroom remodel is much less expensive than a bathroom addition to an existing home.

A bathroom remodel usually requires minimal plumbing expense and is more focused on finish and amenities than actual construction costs. A bathroom addition is a different matter. You incur the construction costs of adding space to your existing home. In addition, you must expect to spend much more on expanding your existing home’s plumbing system and electrical services. The cost of new fixtures adds more to the overall cost of a bathroom addition.

Adding a bathroom to an existing home in New Jersey can cost between $35,860 and $84,600. As with any bathroom addition, the quality of materials and finishes you choose is a major factor in the final cost. The upside of doing a bathroom addition is the increase in home value that generally accompanies the project. Some homeowners see a 50% return on costs in the home’s value almost immediately.

Adding Family Space to an Existing Home

Adding new space for your family to enjoy is a popular addition made to many existing homes. Many times, these additions include an additional bathroom, expanded access to patio areas, or even a small additional kitchen area.

A basic family room addition to an existing home in New Jersey can cost $61,920 to $149,760. Beyond the basic costs of doing a family room addition are the additional expenses for any amenities. Many people include home theater installations as part of a family room addition.

New Kitchen Space

Unfortunately, many people find the kitchen of their existing home inadequate for their lifestyle and entertaining needs. Often the location, size and layout of an existing kitchen precludes a kitchen remodel as a solution. The addition of a new kitchen space frees the old kitchen area for more practical uses as well.

Kitchen additions are perhaps the most expensive home additions. Adding a basic kitchen with mid-range appliances and features can cost between $50,000 and $165,250. Creating a gourmet entertaining area with more floor space, higher-end appliances and specialized equipment can push the cost well above $100,000.

Going Up Instead of Out

Several factors can force a home expansion upwards instead of outwards. Small lot sizes, zoning requirements, and deed restrictions may prevent home additions on the same level as the existing home. Any additional space added to the home requires going up instead of out.

Adding a second story to an existing home is not in the same category as adding an addition. You are, in reality, building a second home on top of your existing home. Building upon an existing structure requires more work when constructing the new space, such as

• removing the old roof structure
• adding the additional structural framework to support the new structure
• building a new roof over the new second floor.
• Adding stairs, new plumbing, and additional HVAC

In most cases, adding a second floor with additional bedrooms and a bathroom costs between $180,000 and $630,000. The costs depend on the complexity of the design, the need to meet local building and fire codes, and current material costs.

Other Home Extension Costs in New Jersey

There are many other possible styles and types of home extensions and additions. We list the more popular types of extensions in the attached table.

What Contributes to the Cost of a Home Addition?

Many people wonder why home additions are so costly. There are many contributing factors, some of which include:

• Building Permits and special testing
• Architectural design or engineering
• Pre-construction site work such as excavation, plumbing, or demolition
• Concrete and foundation preparation and construction
• Roofing materials and installation
• Insulation which is dependent on your geographic location
• Siding or exterior finishes
• Interior finishes such as drywall, molding, and paint
• Floor coverings
• Window and door units
• Plumbing, including rough-in and finish work. Plumbing costs also include fixtures and installation.
• Electrical service work, including rough-in, additional circuits and wiring, and finish work.
• HVAC and ductwork. Your existing system may need replacement if it isn’t large enough to handle the additional floor space.
• Trim and Built-ins. These are usually custom work.
• Landscaping to return your existing home to its visual state after construction
• Cleanup and demolition expenses
• Contractor and labor costs. Your contractor and building both need to make a profit and any laborers hired must be paid.

The Return on your Investment – What to Expect

Apart from the added livability an addition adds to your existing home, any investment in the property should gain a return on the property’s value. In general, New Jersey property owners who invest in additions to their existing home see returns that approximate these percentages

The Dangers of Making Additions to your Home

Extending your home either outward or upward isn’t without risks. You must carefully consider several factors when contemplating making additions to your home.

• Don’t overbuild for your neighborhood. Having the largest home in the development can often cost you value in the resale.
• Maintain the style of your neighborhood. If your development is all single-story homes, being the only two-story home can be detrimental to the value
• Homeowner Association Rules can add costs that don’t result in added value.

Your Contractor or Builder – Know Before You Go

In the end, the success of your home addition or extension depends on the quality and reliability of your builder or contractor. Doing your due diligence before you sign the contract can save you pain and suffering in the long run. Here are some tips for hiring a builder or contractor for your project.

• Ensure that your contractor has licenses in your town or state, is insured and has all the required bonds.
• Check your contractor’s work. Talk to previous customers and visit some of the projects the contractor has completed.
• Choose experience over cost. Contractors who have a track record over several years tend to be more reliable.
• Get multiple bids. See what other contractors are offering for the same job.
• Have a plan to hand to the contractor. A plan with complete specifications and requirements means a more exact bid.