Building Up? Here’s the Cost to Add a Second Story to Your Home

You’ve decluttered, reorganized, and maybe even rearranged some furniture, but there’s no getting around the fact that you’ve outgrown your single-story home. Maybe your family has expanded, or perhaps you’re now working permanently from home. Whatever the situation, you need more space — and you’d rather not go through the hassle or sacrifice of selling a house you otherwise love. Instead, you’re seriously considering the alternative of building up.

To put together this cost guide for homeowners like you, we combined reputable pricing information from our online research with insights from contractors and builders who have spearheaded these types of massive projects in the past.

Before we dive in, be warned: This decision is drastic and probably a lot more expensive and disruptive than you realize. Take the time to digest all of the information, crunch the numbers, and go in eyes-open to determine whether building up is really better than moving on.

National averages for second-story additions

Justin Bride, principal at Ascent Contracting in Denver, Colorado, has worked with many residential expansions. Over the past few years, he’s seen some pretty significant pricing increases for this type of project. These price increases may be attributed to the lingering effects of the pandemic on the supply chain and the economy, inflation, “or whether they are the result of continued increased demand,” he says.

Prices for this project will vary across states and markets, but below are some general averages for adding a second story in the U.S.

Source: Angi

Average cost per square foot: $100-$300

Low and high-end cost range: You’ll pay somewhere between $100,000 to $250,000 for an 800-square-feet addition.

Methodology: Angi taps into its database of thousands of projects, then verifies costs with reputable sources.

Source: Fixr

Average cost per square foot: $100-$300

Low and high-end cost range: Expect to pay $100,000-$300,000 for a home 1,000 square feet or larger. Owners of small homes (~600 square feet) may complete the project for $60,000-$180,000.

Methodology: Fixr pulls its cost data from multiple sources, including “specialized publications, websites, cost studies, U.S. associations, reports from the U.S. government, contractors and subcontractors, material suppliers, material price services, and other vendor websites.”

Source: HomeGuide

Average cost per square foot: $200-$500

Low and high-end cost range: Depending on the size of the space and quality of the materials, HomeGuide estimates a price range of $200,000-$750,000 for this project.

Methodology: HomeGuide receives millions of requests for home improvement cost estimates every year. The site then tracks cost estimates consumers get from local companies and shares pricing information.

Types of second-story additions

Not all second-story additions have the same scope. Depending on how much space you need and the size of your budget, you can choose from the following options:

Full-story addition

If you need a lot of extra space, you can opt to add a full second story that’s roughly the same size as the first story. In the below example, a full second story was added to this Denver, Colorado home:

Source: (Ascent Contracting)

Source: (Ascent Contracting)

Partial addition

If you only need to add a small amount of extra space — perhaps an extra bedroom and bathroom — and are working on a smaller budget, adding a partial second-story addition might be the way to go.

Architect Jeff Pelletier points out in a blog post that whether you add just one primary suite or three additional bedrooms and a bathroom, many of the associated costs (not to mention the disruption to your day-to-day life) will be largely the same. “I usually advocate to aim for the three-bed/two-bath second floor,” he recommends. “It is a solid investment as it is so desirable, and helps ensure the value of your investment.”

Below is an example of a partial second-story addition in California:

Source: (Design Everest)
Source: (Design Everest)

Bonus room addition

Another way to increase your living or storage space without expanding your house’s footprint is to add a bonus room over the garage. It could be used as a home office, in-law suite, man cave, playroom, craft room, storage room… the possibilities are endless. One of the main benefits of going this route is that because you’re building on top of an unfinished garage, you don’t have to worry as much about damaging existing drywall, flooring, or other elements during construction, which means there will be less need to remodel the space after the addition is complete.

Not all garages are candidates for supporting bonus rooms without significant structural rework to the existing foundation, particularly in the case of detached garages. “Sometimes it makes more sense to demolish the existing garage if the goal is to build a new garage with an ‘accessory dwelling unit’ (or ADU) on top,” says Bride, the Colorado contractor.