How Much Do Home Additions Cost?

Leah Lopez Cardenas
Updated June 7, 2022
Large and open living room leading into sunroom with windows on two sides and lots of natural light flowing in. There is a window seat on one side and a leather couch and plant on the other.
Photo: Ursula Page / Adobe Stock


  • The average cost to add a first-floor room is $80–$200 per square foot.

  • Second-story additions cost more, between $100–$300 per square foot.

  • Before you build, you have to apply for the appropriate permits.

  • It’s always best to hire a pro for a large project like a home addition.

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Making the decision to add to your home can be daunting, but it can also pay off majorly in the future. When properly executed, a home addition will no doubt add value to any home—and allow you to entertain guests and enjoy your space to the fullest.

Room additions come in many different sizes and types, from outdoor sheds to sunrooms to full-blown primary suites and everything in between. There is an almost overwhelming number of home addition costs to budget for, including contractor labor, materials, permits, and more, so we’ve broken it down to help you plan for your project.

How Much Do Home Additions Cost per Square Foot?

If adding on a first-floor room, the average cost is $80 to $200 per square foot, while second-story rooms typically run $100 to $300 per square foot.

For example, a 10-by-10-square-foot room on the first floor will cost anywhere between $8,000 and $20,000. The same-size room on the second floor will cost $10,000 to $30,000. A 12-by-12-square-foot space on the first floor will cost between $11,520 and $28,800; on the second floor it would cost $14,400 to $43,200.

What Factors Influence Home Addition Costs?

Home addition costs can vary greatly based on the size and scope of your individual project, who you hire, and the permits and materials you’ll need to complete the job. While it can seem daunting at first, that’s why hiring a contractor can take some of the burden off your shoulders and ensure you’re getting the job done right.

4 cost factors for home additions, including size, materials, and permits
Photo: Sidekix Media/Unsplash


While you may have your heart set on a larger home addition, the bigger it is, the more expensive it will be, so you’ll want to factor that into your budget. Be sure to include other costs as well, such as the laying of a new foundation (which costs $75 per yard), along with insulation, site preparation (if extending the perimeter of a house; excavation costs $2,559 on average), and electrical wiring.

Hiring the Right Home Addition Contractor for Your Project

You'll want to ensure a crucial task like this is done correctly, so avoid wasting time and money (and potential need for a rebuild if something goes awry) and ask a home addition contractor near you for an estimate. Ideally, you’ll actually want to ask three potential contractors for three different quotes to get a good sense of what is out there.

Some contractors offer free estimates, but if your project requires substantial consulting or design work, you may need to factor in an extra $150 to $1,000 to cover the expense of the consultation.

Permits Needed

Before starting a new home addition project, you’ll have to apply for various building permits from your city or township. The permits you need for a home addition may include structural, electrical, plumbing, gas, and other local permits outlined by your municipality.

According to HomeAdvisor, the average cost of a building permit is $1,300, but they can cost as little as $150 in small towns or as much as $7,500 in some cities.


Common building materials you’ll need to complete a room addition include:

How Much Do Home Additions Cost Near You?

Prices can vary city-to-city based on the size of your home, the cost of the project’s materials, and the type of room you want to add on. For example, a homeowner in a balmy southern state may be more likely to add a front porch or a pool house, while a homeowner up north may want to add a heated sunroom to enjoy the view of the great outdoors even in cold winter months.

Whether you live in an urban or rural area, the amount of land you have available can also help to determine whether you can build out or have to build up, which can also impact the price.

Here’s a breakdown of home addition costs near you based on what region of the country you live in:

  • San Diego: $77,250

  • Denver: $50,180

  • Austin, TX: $26,460

  • Madison, WI: $36,840

  • Tampa, FL: $36,470

  • Philadelphia: $54,170

What Kind of Home Additions Can I Get on My Budget?

You can expect to pay at least $21,000 for any home addition project, but the specific type of materials needed, where you’re building the addition, and what labor you’ll need can quickly increase these costs.

$21,000 to $50,000

With this budget, you can expect to be able to build a small 10-foot-by-12-foot room with few complexities, such as a walk-in closet, laundry room, mudroom, kid’s bedroom, or garage or outdoor shed.

$50,000 to $100,000

A mid-range budget will get you a larger 400- to 500-square-foot room with more complex elements like substantial electrical work, plumbing, ductwork, or cabinetry. A new kitchen, bathroom, heated sunroom, large living room, or primary bedroom falls in this price range.


At the high-end of the spectrum, homeowners can dream up huge 1,000-square-foot rooms, second-story home additions, a full studio apartment, or much fancier kitchens, bathrooms, and main bedroom suites with all the bells and whistles, including nicer finishes.

How Much Does It Cost to Build a Home Addition Yourself?

This is a complicated job you won’t want to tackle entirely on your own. Most homeowners consult an architect to ensure the design matches the rest of the house and a structural engineer to ensure construction is safe. Oftentimes, you’ll also need to hire an electrician, plumbing expert, or other construction contractors to make sure you build your home addition up to code.

However, there are certain parts of a room addition project that you can do yourself, such as hanging drywall, laying flooring, installing cabinetry, or painting. Taking a DIY approach to these tasks can save you money on the cost of labor to have a contractor perform them. Contractor labor costs make up about 30 to 50% of your total budget.

How Much Does a Room Addition Cost by Type?

The cost to add on a room varies based on the type and size of the room you’re building. When you’re looking to add an additional room, you can choose to either build out or build up. If you build out, the cost averages $80 to $200 per square foot, while second-story rooms typically run $100 to $300 per square foot.

Pricing varies depending on the type of room addition, with bathrooms averaging $6,200 to $15,500


It is common to add rooms such as an extra bedroom so you can finally host your friends from out of town or a family room perfect for movie nights. A 9-by-12-foot bedroom, for example, would cost $8,600 to $21,600. However, a full primary bedroom suite could cost over $100,000 with the inclusion of a bathroom.


A standard bathroom addition might cost between $6,200 to $15,500. The square footage and extent of new plumbing and electrical wiring needed may be the largest influencers on your overall bathroom addition price.


Sunrooms average $16,315, but can go up to $70,000 for an addition covering 200 square feet with a foundation. The cost of adding a sunroom varies depending on the amount of space it will cover, location, and extra necessities such as electric wiring and heating.

When hiring a local sunroom building pro, typical costs can include electricians ($50 to $100 per hour), carpenters ($70 per hour), and painters ($20 to $35 per hour).

If you’re opting to buy a sunroom, it will average $11,000 per 150 square feet. Extra costs, such as electricity and heat, will cost $300 to $400 per square foot.

It’s wise to get a few price estimates before buying a sunroom to get the best price possible.

Living Room or Family Room

A comfortably sized 18-by-12-foot living room add-on costs in the range of $17,300 to $43,200.


The cost of a new kitchen addition is likely around $48,000 to $95,000; however, because kitchens feature many different appliances and electrical outlets to power all your gadgets, you’ll need to budget for any new electrical wiring needed for the room (averaging $1,175).

Detached Garage, Shed, or Outbuilding

Detached additions vary in style and price. Simple shed-like structures cost $15,000 on average without electricity or heat, and full guesthouses may average $24,700. Enlisting the help of professionals like a local general contractor, electrician, and painter is often needed to finish a detached addition.

In-Law Suite

Rates vary widely for in-law suite home additions. A simple bedroom unit costs around $44,000, while it can be as much as $100,000 for a full unattached suite. Check in with your city before starting a project like this, as they may not be allowed in your area.

Front Porch

The cost of adding a new front porch can also vary greatly, ranging from $4,600 to $22,200. Before you start any sort of home addition construction project, it’s best to get at least three quotes from the general contractors you’re looking to hire in order to get the most accurate price estimate.

FAQs About Installing a New Home Addition

Will a home addition add value to my home?

Absolutely. In fact, you’ll likely see a drastic increase in your home valuation for adding a room. For example, you may see as much as 63% ROI after adding a new primary suite.

How can I save money on home addition costs?

Check around with different home addition pros near you to get quotes, then compare pricing and the pros and cons of each. We recommend starting with at least three or four general contractors.

Buying materials in bulk yourself, choosing more budget-friendly finishes, and DIYing parts of the job that you’re capable of handling safely on your own can also be ways to save money.

How far in advance should I start planning my home addition project?

While it’s never too early to start planning for a major home renovation like this, give yourself at least a couple of months for planning and designing your room, finding a contractor, and getting the permits in order. Then, plan for another two to three months to complete the home addition itself.

Is it cheaper to add on or build up?

Building out involves adding a room on the ground floor of a house. It is one of the most popular additions sometimes performed by smaller local home construction companies.

Building out increases the footprint of a home by extending it outward. This type of construction can be costly as it might involve the construction of a new foundation or acquiring a zoning license to expand.

Building up involves adding a room to the second story of a house without increasing the home’s footprint, which makes this the cheaper of the two solutions. However, a contractor may need to strengthen the existing foundation to support the added weight.

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