How Much Does It Cost to Add a Second Story to Your Home? [2025 Data]
The average U.S. homeowner spends $175,000 on the cost to add a second story, but it ranges from $100,000 to $250,000, depending on the scope of the project.
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. 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.
| Size (Square Footage) | Average Cost Range | Maximum Range |
|---|---|---|
| 800 | $80,000–$240,000 | $400,000 |
| 900 | $90,000–$270,000 | $450,000 |
| 1,000 | $100,000–$300,000 | $500,000 |
| 1,100 | $110,000–$330,000 | $550,000 |
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.
| Type | Cost |
|---|---|
| Full second-story addition | $600,000 |
| Partial second-story addition | $300,000 |
| Converting a vaulted ceiling | $20,000 |
| Dormer addition | $12,000 |
| Bonus room | $60,000–$120,000 |
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.
| City | Full Second-Story Addition | Partial Second-Story Addition |
|---|---|---|
| Los Angeles, CA: | $500,000–$1,000,000 | $150,000–$300,000 |
| Denver, CO: | $350,000–$600,000 | $200,000–$300,000 |
| Houston, TX: | $300,000–$600,000 | $100,000–$130,000 |
| Seattle, WA: | $400,000–$700,000 | $250,000–$300,000 |
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.
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.
Frequently Asked Questions
Most single-story homes don't have foundations strong enough to support a second story, but they can be reinforced for an addition. A structural engineer can assess your foundation and what needs to be done to get it ready. They'll look at any cracks or unevenness in your current foundation and consider any special framing or beams your home needs, especially if it’s in a high-wind or hurricane area.
“To support a second story, many structural engineers will require that you install additional concrete piers in the crawlspace,” says Tschudi. “This involves hand excavating, pouring a large concrete footing—usually with specially coated rebar—and then building concrete piers right up to the girders.”
Whether building a second story is less expensive than building an addition depends on the size of the project. Everything else being equal, a second story is less expensive than a new addition for one important reason: There’s little to no foundation work when building up. That cuts out an expensive part of the process. However, other structural details can still have an impact, so explore your options.
Sometimes. Professionals may be able to remove the old roof and re-attach it when completed, depending on your blueprints. That can help you save money. But this method is not without its risks. Larger roofs may crack during the transportation process. And if the roof is old or has problems, it may be better to replace it entirely. Keeping the old roof isn’t always possible if you are making significant alterations to the roofline.
Since building up tends to provide useful bedrooms and other extra spaces without the need to do a lot of foundation work and cut into your yard, second stories tend to have better ROI—up to 65%—than other kinds of additions. But ROI will depend on the type of rooms you are planning and what your current house has. It’s not a very reliable way to judge the success or failure of a project, so consider other factors as well.
A second-story home addition takes approximately six to 12 months to complete. The process involves pulling permits, securing the foundation, framing, roofing, and interior work. A partial addition may only take three to five months, but this depends on your local laws and the availability of framing materials. It is also important to account for the amount of design and brainstorming time, as it's best to take your time with such significant changes to your home.
