How Much Does It Cost to Add a Second Story to Your Home? [2025 Data]

Adding a second story to your home is a significant undertaking that adds value, comfort, and space to your existing house. On average, the cost to add a second story is $175,000, but it often ranges from $100,000 to $250,000 depending on the size, design, and other factors. The total cost comes down to the square feet, the condition of your existing structure, and what types of rooms you’re adding.

Cost to Add a Second Story per Square Foot

A second-story addition costs between $100 and $300 per square foot on average, but complex projects with high-end materials could reach as high as $500 per square foot.

Cost of Adding a Second Story by Type

When you can picture your second-story design idea but can't quite put it into words, take a look at the costs by the type of addition. Every second story will be unique, but they typically fall into one of the following five categories.

• Full Second-Story Addition: Building a full second floor over your current layout requires stricter foundation requirements to build the second story. You will also spend more on windows, roofing, insulation, and all of the homey features that round out your second floor.

• Partial Second-Story: These additions are popular for their flexibility and comparatively lower costs. They may include a guest bedroom, an extra bathroom, or a flexible space for an office.

• Converting a Vaulted Ceiling Into a Second Story: A vaulted ceiling adds lots of airy space to a house, but some see all that space and wonder if it could be used differently. If the ceiling is higher, it’s possible to convert it to a partial addition or loft to create usable space. 

• Dormer Addition: A dormer is a triangular window space on top of a roof. It is a common addition used to expand an existing second story and give second-story rooms more light and a bigger feel. Dormer costs start at $6,000 but can reach $30,000.

• Add a Bonus Room Above the Garage: While adding a room above a garage, square footage plays a role, but you'll also have to ensure the garage's structure can handle the extra weight. The second floor may also require additional insulation and vapor barriers.

Cost to Hire a General Contractor to Add a Second Story

Adding a full second story or even impactful additions like a dormer window are large projects. You can hire a general contractor or a home addition pro near you to manage such big remodels for you. A general contractor is an experienced local builder who can take charge of the whole addition, provide you with useful estimates, and construct a timetable for the project.

In addition to their own teams, general contractors connect with any necessary subcontractors and can recommend or schedule architects and obtain permits.

General contractor costs depend on the scope of the build, but they rarely charge per hour for their work. Instead, they often charge a fee that is 10% to 20% of the project’s cost. The more of their team they bring in and the more subcontractors they hire, the higher the estimate. For projects as large as this, we always recommend getting a least three different estimates to compare local prices and find the best option. Also, always work with a general contractor with extensive experience, licensing, and insurance.

Cost to Add a Second Story By Location

Location significantly impacts the cost of major additions. Contractor fees, the price of materials, and shipping costs all vary considerably. Certain regions may require additional insulation, roofing materials, or siding protection against snow, wind, or rain. Here’s a look at some prices in certain U.S. cities.

Second Floor Addition Cost Factors

Because adding a second story is a large and often complex project, several factors influence the cost of your addition. 

Building Permits

You’ll need to make sure you pull the proper building permits for your second-story addition. Your building contractor typically handles this, but the cost of a building permit ranges from $1,200 to $2,000. If you come up against strict laws in your area and your permit is turned down, keep in mind that you may also need to pay for legal assistance to decipher the laws. Historic homes, HOAs, and areas with strict air rights can be complex to understand without a legally trained eye.

Quality of Finish

If you choose higher-end materials, such as stone siding or marble bathroom flooring, expect your costs to be higher than builder-grade materials. While some high-end materials reduce maintenance costs, many standard finishes are still durable and save money in the total project price.

Foundation Reinforcement

Depending on the structure of your existing home, your foundation may not be strong enough to support a second-floor addition. You'll want to hire a local structural engineer to evaluate your foundation and see what may be needed to strengthen it.

Foundation support work costs $5,000 or more. Where you live, seasonal weather patterns, and ground characteristics all factor into the amount of work needed. 

Demolition

In many cases, building a second story requires that your contractor remove the roof and then open up walls and ceilings in order to reinforce your home’s framing. Removing a room costs an average of $1,250—and the cost to replace the roof when all is said and done falls between $4.35 and $11 per square foot. And while designers often work around existing chimneys, the price to remove a chimney for a second story adds an average of $4,500.

Adding a Staircase

Installing the main staircase in your home costs between $2,400 and $4,000, but high-end designs reach up to $6,000. General contractors will often include this price in the second-story price estimate, as it's a crucial element of the design. However, the placement of your stairs, the design, and additional elements such as carpeting can raise the price.

Landscaping

While not as common, the landscape surrounding your home may change when you add a second story. Construction equipment can damage your lawn, garden, and—though hopefully not—the surrounding trees. Due to a shift in the shadows of your lawn, you may choose to move certain plants and flowers that sat in direct sun before the build. Professional landscaping costs between $4.50 and $12 per square foot.

Temporary Housing

For safety purposes, you'll need to be out of your house during the construction of your second-story addition. A partial addition can take three to six months to complete, while a full second-story addition can take six to 12 months. If you don't have a nearby relative or motorhome where you can stay, factor in the price of a rental into your project.

Before You Start: Check Local Regulations

Zoning laws will set restrictions on building a second story, so always start your design process by reviewing these with a professional. Regulations will cover foundation changes, expansion of your septic system, and structural requirements. If you add a fully functional living space on the second floor—such as with a bathroom, kitchen, and separate entrance—your zoning board may consider the addition of a multiple dwelling unit.

When you work with a contractor, they will have experience pulling permits and can walk you through the process. Your design plans may require a certified stamp of approval from a structural engineer, electrician, and plumber before starting.

Building a Second Story Yourself vs. Hiring a Pro

Labor usually accounts for 30% to 50% of your second-story addition budget. Tackling the entire project without contractors isn’t advisable unless you’re an experienced builder. Hiring a general contractor ensures the project meets code, stays on budget, and maintains a high standard of work. They'll also subcontract other pros like roofers and electricians.

“We recently added a second story to a 900-square-foot house in an urban area,” says Bob Tschudi, Expert Review Board Member and Raleigh, N.C.-based general contractor. “One thing that surprised us was that the municipality required a building elevation survey after construction to verify that the peak of our roof was within inches of what we had on the blueprint. Fortunately, we have great framers and it was, but if you are doing it yourself, be sure to measure often.”

But you can still save costs by doing some of the work yourself, such as painting or installing bedroom flooring. Adding bathroom fixtures, ceiling fans, and other similar finishing touches are also an option. Just be sure that the project you plan to DIY does not require a permit in the context of a new addition.

Why You Should Hire a Home Addition Contractor

When you hire a local home addition pro to add a second story to your house, labor will make up to 50% of the total project costs—but this is not a job you can DIY unless you’re an experienced and licensed builder. This job involves significant structural, electrical, and plumbing work that requires a team of specialized professionals to complete safely and in compliance with local zoning laws and building codes.

Here’s why it’s ideal to hire a home addition pro

You can save on project costs by doing small finishing touches, such as painting or installing carpeting (as long as they don’t require a permit), but it's best to leave the majority of the build to your home addition contractor. Here’s why:

• Additions involve significant structural complexities, and miscalculations can cause a serious hazard. 

• Simple mistakes, like improper framing or joist alignment, can make your home unstable and potentially cause the building to collapse.

• Mistakes in wiring, gas line installation, and insulation can create a fire or explosion risk.

• Improper plumbing can lead to leaks, flooding, and substantial water damage.

• There’s a serious risk of injury during construction, including a fall risk and the risk of electric shock.

• Home addition contractors have the expertise and equipment, like professional scaffolding and safety gear, to complete this job safely.

• Pros will make sure your addition complies with local building, plumbing, and electrical codes, as well as zoning laws.

• Home additions require several permits, which must be obtained by a licensed contractor.

• Most cities require licensed structural engineers to create the plans.

• This job is extremely labor-intensive and takes months to complete, even with a professional team.

• Pros can usually get materials at a lower cost than homeowners.

• Poor craftsmanship and missing permits may sink your home value and create issues with resale.

• DIY work may void your homeowners insurance and material warranties.

How to Save Money on Second Story Addition Costs

While you don’t want to cut corners when it comes to a second-floor addition, there are ways you can save money on the remodel project without forgoing quality:

• Keep the blueprints simple: When working with an architect, choose the simplest ways to add a second story. Keep your roofline, structural beams, and first-story walls as intact as possible. The fewer changes you need to make, the less expensive the project. The architect may be able to suggest less expensive ways to complete the addition.

• Arrange to use your old rooftop: If your old rooftop is in excellent condition and you won’t be changing the roofline much, see if you can remove it intact, add a second story, and then install it back into place. While that sounds expensive, it’s less expensive than building an entirely new rooftop.

• Choose modular pieces when possible: Modular pieces are pre-fabricated and shipped for easy, quick installation. They won’t fit on every home, but if they’re an option for your home design you can save a lot of money by choosing a modular addition. Ask your architect about these options.

• Cut down on high-end finishes: Finishes are an excellent way to cut down on less-necessary costs. Choose more affordable finishes to save money. This is one feature that you can always upgrade years down the road.

• Skip plumbing amenities where you can: If your second story doesn’t absolutely need a bathroom, skip it. This will remove any major plumbing work and can save you big bucks.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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