How Much Does It Cost to Add a Second Story?

Average Cost to Add a Second Story

Cost to Add a Second Story per Square Foot

Building a second-story addition typically costs between $100 and $300 per square foot. For complex projects with high-end materials, it could cost as much as $500 per square foot. A 900-square-foot addition at an average cost of $200 per square foot costs roughly $180,000.

Second-Floor Addition Cost Breakdown

The two largest factors to consider when calculating the cost to add a 2nd story are material prices and labor rates. Material and labor costs continue to soar in recent years, which has led to an increase in overall project costs.

Material Prices

The quantities and types of materials necessary will depend on the size and scope of the project. You’ll need to budget for construction materials like lumber, piping, and electric wiring, but also for interior finishes, from flooring to fixtures. Typically, materials will make up at least 50% of your total budget.

Below are examples of common materials required for most second-story additions:

Labor and Additional Pros

You’ll typically hire a general contractor to complete a second-story addition on a home. Rather than an hourly rate, general contractor fees are usually about 10% to 20% of the total construction project cost.

Depending on your needs, you’ll have to factor in the cost of dealing with various other professionals during the project in both the design and construction phases. Depending on the project, you may need to budget for the following labor costs in the design and planning phase:

• Architects cost 5%–20% of the overall project cost, or roughly $125–$250 per hour. You’ll at least need an architect to sign off on the plans, but you might be able to save money with hourly draftsperson rates for the blueprint creation, about $50–$130 per hour.

• Engineers charge $100–$200 per hour.   

• An interior designer costs $50–$200 per hour.

And don’t forget to budget for the cost of construction permits, which could go as high as $2,000.

Once you have the green light to move forward, your contractor will also coordinate various subcontractors for the work, so budget for the following:

• Plumber fees: $45–$200 per hour.

• Carpenter hourly rates: $13–$39 per hour.

• Electrician costs: $50–$100 per hour.

In addition, you may need to hire an HVAC specialist, find a local flooring installer, hire painters, contract local roofers, and even budget for foundation repair costs, if necessary, before work can begin. Your general contractor will be able to coordinate all the moving parts—and bake their costs into one large fee for you to pay.

Second-Story Addition Cost Factors

Adding a second story is a big project, and various factors can influence the amount you will spend.

“We recently added a second story to a 950-square-foot house,” says Bob Tschudi, an Expert Review Board Member and Raleigh, N.C.-based general contractor. “One surprise cost was that the municipality required that we have the newly-constructed building re-surveyed to ensure that the structure's roof was within 2 inches of what we proposed. So, it’s critical that you hire a contractor who understands blueprints built to specification.”

Various factors can impact the overall cost to add a second story to your home:

Size and Shape

It’ll cost more to add a full second-story addition on top of a 2,000-square-foot single-story than building an apartment over a garage or a partial second story on top of a 1,000-square-foot home. Complex shapes also increase installation costs.

Quality of Finish

If you opt for slate roof tiles, luxury hardwood flooring, or architecturally designed windows, this will cost more than asphalt shingles, carpets, or standard double-hung windows. While selecting a higher-quality finish can reduce the frequency of repairs and increase your overall home value, you can reduce your costs by selecting more affordable materials.

Location

The cost to hire contractors in desirable city locations will be more than in rural locations. However, more densely populated areas often offer more contractors to choose from.

If you live in a remote location, coordinating multiple contractors to drive out to your property can mean higher prices as well.

Foundation Work

Depending on the type of second-story addition you’re planning and the structure of your existing home, the foundations may not be strong enough to support the additional weight.

You’ll need to hire a structural engineer near you to establish whether there’s a requirement for further foundation work before the project begins. Additional foundation support work costs could be $5,000 or more.

“To add the second story, we had to jackhammer out boulders under the house before we could pour new concrete footings and piers, “ says Tschudi. “Then we had to install a costly parallel-strand-lumber (PSL) column from the pier to the steel beam—we were creating an open-concept first floor, so the engineering had to be right.”

Temporary Housing

Timelines for constructing a full second-story addition can be around six to 12 months. Even partial additions can mean you have to be out of your house for as many as three to six months. If you don’t have an obliging relative or motorhome you can reside in temporarily, you may need to factor in additional rental costs for the duration.

Full vs. Partial Addition

A second-story addition does not have to share the same footprint as the floor below it. You’ll save money by only doing a partial addition on top of your first floor instead of a full addition. In general, homeowners spend between $80,000 and $250,000 on partial additions and $100,000 to $600,000 or more on full additions.

Cost to Add a Second Story Yourself

Typically, labor costs make up 30% to 50% of the total cost of a second-floor addition. While tackling the entire project without the help of contractors isn’t advisable unless you’re an experienced builder, you can cut costs in some places. For example, you can do interior and exterior painting or lay the floors if you’re handy, and it may save you around $1,000 or more.

DIY Second-Floor Addition vs. Hiring a Building Contractor

Hiring a local home builder not only ensures a high standard of work, but they can subcontract electricians and plumbers and keep the project on track, within budget, and, most importantly, safe. Most contractors will help with building permit applications and liaise with other professionals such as architects and engineers.

Tackling a second-story addition on your own without understanding the complexities of constructions and building code requirements can result in a project going over budget, could take years to complete, and may not be up to local building standards. You could end up with an unsafe home that’s difficult to insure or sell.

FAQs

Is it better to build up, out, or replace altogether?

Home addition costs vary considerably depending on their size and complexity. If you have limited space for building out and your foundations don’t need strengthening to build up, it may be more cost-effective and practical to build a second story. Building out is a better option if there are zoning restrictions relating to building height or you want to stay in your home during construction.

Depending on the additional story’s complexity and your home’s age and condition, it can sometimes work out cheaper to demolish the existing building and start again. But this won’t make sense if you’re planning a simple partial second-story addition or you have a historic home full of character.

How do I find the best contractor for the job?

The pros involved in your second story addition can make or break your project. When searching to hire a local building contractor, take the time to get multiple comparative quotes.

Ask to see portfolio photos, follow up on references, and check contractor credentials—they must have a license and insurance. Get a written contract before work begins and check all the details. This includes timelines, work descriptions, cost breakdowns, payment schedules, and permit details.

How can I keep the costs down on my second-story addition?

Compromising is often the key to keeping the costs down on your projects. While you might not want to go with budget finishes, you don’t need to choose the most high-end options. If your architect suggests a different, simpler layout to keep the costs down, don’t dismiss it without proper consideration. Also, you could save some money by tackling some of the more straightforward elements of the building work yourself, like painting.

How long does it take to build a home addition?

The length of time it takes to complete a home addition depends on the project’s complexity. Don’t be surprised if your home addition takes over a year from project conception to completion. In general, plan for two to three months for the actual build, with time up front for design, inspection, and permits. The ongoing industry supply and labor shortages can add significant time to projects.

Does adding a second floor increase home value?

A second floor could significantly increase the value of your home; square footage is a large determining factor in the overall value of a house. Buyers with growing families may also be more likely to make an offer if you have more bedrooms and bathrooms, so on top of the increased asking price, a second-story addition could help your home sell faster.

Will my foundation support a second story?

To determine if your foundation could support a second story, you will need to hire a structural engineer to assess your home’s foundation. But don’t stress: If the engineer determines your current foundation cannot support a second floor, there are things you can do to reinforce the foundation that will enable it to support an addition.