Home Addition Cost Calculator

Popular house additions include: an extra bedroom, bathroom, kitchen, office space, entertainment room, and more with one simple search.

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How much does it cost to build a home addition?

Generally, building a home addition in the US will set you back between $22,000 and $80,000. This covers the cost of the materials and work for a straightforward addition like a 10-by-10-foot bedroom, a 15-by-15-foot living room or a 20-by-20-foot family room. But if you want something more elaborate, like a second-story addition or a full kitchen makeover, you can expect to pay more. The cost of building a home addition can vary widely depending on a number of factors, such as the size and complexity of the project, the materials used, the location of the property and local labor costs. As a result, providing a specific cost estimate can be difficult without knowing the details of the project.

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How much does a room addition cost?

Again, total costs can vary significantly based on a number of factors. But broadly speaking, here's what you can expect to spend to build out the following types of rooms.


Adding a bedroom costs an average of $200 per square foot. The average bedroom size in the US is about 132 square feet, meaning you can expect to pay about $26,000 for a new, average-sized bedroom. Adding a 12x12 bedroom costs about $11,520–$28,800 on average. A master bedroom suite costs about $21,000–$63,000 on average, depending on the size and extent of the addition, especially if it includes a walk-in closet and master bathroom.


The cost to add a bathroom ranges from $9,000 up to $74,000. On average, adding a basic bathroom with a toilet, sink, and shower can cost between $5,000 to $15,000. However, if the bathroom is larger or includes high-end fixtures and finishes, the cost can be significantly higher, ranging from $20,000 to $50,000 for a bathroom home addition for a 6 by 8-foot bathroom addition.

The cost depends on (a) where the bathroom is located and (b) whether or not you'll need to add square footage to accommodate it. Adding a bathroom to an accessible place with existing plumbing—a laundry room, for example—will cost less than adding square footage and new plumbing.

If significant plumbing or electrical work is required, the cost can also increase. It is important to obtain detailed estimates from licensed and experienced contractors to accurately determine the cost of adding a bathroom to a specific home.


The average cost to build a new garage is about $24,000, but the actual costs can vary significantly. At the low end, a detached, single-car garage with no electricity or plumbing can be built for less than $2,000. On the high end, an attached, three-car garage complete with a loft, plumbing and electricity can cost more than $60,000.


A three-season sunroom costs roughly $80 to $230 per square foot, while a four-season sunroom starts at about $200 per square foot and can be as much as $400 per square foot. The difference is that four-season rooms include HVAC and insulation so they can be enjoyed year-round. Three-season rooms lack insulation, use lower-quality materials and typically have no heating or air conditioning.


At about $21 per square foot, decks are a relatively cost-effective way to increase your living space compared to other additions. For an average 350-square-foot deck, expect to pay roughly $7,000 to $8,000 depending on the materials used and the complexity of the design.

Factors that drive up home addition costs

There are several factors that can drive up the cost of a home addition, including:

Size and complexity

In general, the larger and more intricate the project, the more it's going to cost. A home renovation will usually be cheaper than a home addition.

Structural changes

If the addition requires significant structural changes to the existing home, such as removing load-bearing walls, the cost will be higher. These types of  projects not only involve additional materials but specialized workers (e.g., engineers) as well.


The type and quality of materials used can greatly impact the cost of the project. Hardwood flooring costs more than carpet, for example, and designer plumbing fixtures are more expensive than their builder-grade counterparts.

Permits and fees

Depending on the location of the property, permits and fees can add significantly to the cost of the project.

Labor costs

The cost of labor can vary widely depending on the location and complexity of the project. Higher cost living areas tend to have higher labor costs.

Site preparation

If the site requires significant preparation work, such as excavation or demolition, this can increase the cost of the project.

Plumbing, electrical and HVAC

If the addition requires new or upgraded plumbing, electrical or HVAC systems, this can also add to the overall cost.


If the addition is in a hard-to-reach location, such as a second-story addition or a backyard that is difficult to access, this can increase the cost because of the additional labor and materials needed to transport materials to the site.

Design and architecture

If the addition requires a custom design or architectural features, this can increase the cost because of the additional time and labor needed to create the plans and complete the project.

How to finance a home addition

A home addition can be expensive, but it doesn’t have to break the bank. Here are some of your options.

Home equity loan

A home equity loan is a type of loan that allows you to borrow against the equity in your home. This type of loan usually has a fixed interest rate and a repayment period of 10 to 30 years. Homeowners can use the funds from a home equity loan to pay for a home addition.

Home equity line of credit

(HELOC): Similar to a home equity loan, a HELOC allows you to borrow against the equity in your home. However, a HELOC is a revolving line of credit that you can draw on as needed. This can be a good option if you need to pay for a home addition in stages.

Personal loan

A personal loan is an unsecured loan that you can use for any purpose. Personal loans usually have higher interest rates than home equity loans or HELOCs, but they may be easier to qualify for.

Permits and fees

Depending on the location of the property, permits and fees can add significantly to the cost of the project.

Credit card

If you have a high credit limit and can pay off the balance quickly, a credit card can be a good option for paying for a small home addition. However, keep in mind that credit cards usually have high interest rates.


If you have enough equity in your home, you may be able to refinance your mortgage to pay for a home addition. This option can be a good choice if you can get a lower interest rate than your current mortgage.

Cash-out refinance

A cash-out refinance is similar to refinancing, but you borrow more than the amount of your current mortgage and receive the difference in cash. This can be a good option if you need a large amount of money for your home addition.


If you have enough savings, you may be able to pay for your home addition without taking out a loan. This option can be a good choice if you don't want to take on debt.

FHA 203(k) loan

If you're a new buyer and you're purchasing a home that needs repairs or upgrades, you may be able to use an FHA 203(k) loan to finance the cost of the home addition. This type of loan combines the cost of the home and the cost of repairs into one loan.

VA renovation loan

If you're a veteran or an active-duty service member, you may be able to use a VA renovation loan to finance the cost of a home addition. This type of loan is similar to the FHA 203(k) loan but is only available to eligible veterans and service members.

USDA home improvement loan

If you're purchasing a home in a rural area, you may be able to use a USDA home improvement loan to finance the cost of a home addition. This type of loan is only available in certain areas and is subject to income limits.

How home additions can improve the value of a home

A home addition can significantly improve the value of a home by increasing the total square footage and adding more functional living space. Homeowners may choose to add a bedroom, bathroom, or even a whole new wing to their house, which can create more space for family members or guests. Additionally, the added space can increase the home's resale value, making it a wise investment for the future.

A well-designed and executed home addition can also enhance the aesthetic appeal of a home. The addition can be designed to match the style and architecture of the existing home, creating a cohesive and seamless look. This can greatly improve the curb appeal of the property, which can make it more attractive to potential buyers if the homeowner decides to sell the property in the future. Overall, a home addition can be a smart investment for homeowners looking to increase the value and functionality of their home.

Whether you’re planning on a modest home addition like a single small room to be your office, or a full-scale expansion of your home to a second floor, the cost of home additions can vary widely depending on location, labor costs, material, local regulations and other factors. NeighborWho can be a great starting point to help you figure out your budget and expenses, but you’ll also want to consult a certified contractor and do your own research before getting started.