How Much Does It Cost to Add a Second Story? (2024 Guide)

Highlights

• The cost to add a second story is about $175,000, but a typical average is $100,000 to $250,000.
• The size of the addition and the home are the biggest cost factors, but homeowners will also need to consider the cost of adding plumbing, electrical lines, HVAC, and any foundation structural work.
• Adding a second story gives homeowners more living space without sacrificing existing outdoor living space, and it also increases the home’s value.
• Any major construction project that alters the home’s design is a job that’s best left to general contractors and licensed professionals who have the experience, equipment, and time to complete the job to code.

Homeowners can choose from a number of home projects to improve the look and functionality of the house. Sometimes the house simply does not have enough space, so homeowners can opt to install an addition or second story. Generally, an addition will be added to the exterior of the home on the ground floor. However, single-level homes may be able to increase the living area by adding a second story.

According to Angi, the cost to add a second story to an existing house is about $175,000 on average, though the cost can range from $100,000 to $250,000, depending on the size of the addition, current home size, and many other cost factors. Given the financial investment required for this project, it’s a good idea for homeowners to find out more about the project scope and cost considerations.

Key Cost Factors

Building a second-story addition is a complicated project that involves a wide variety of elements, such as framing, plumbing, electrical work, HVAC installation, drywall, floor installation, and more. The project complexity means that the cost to add a second story can vary greatly depending on the size of the addition, the existing layout of the home, and the local labor rates. Keeping these cost factors in mind can help homeowners create an accurate budget for this job. 

Addition Size

The size of the addition has the greatest impact on the cost to add a second story. Contractors will estimate costs for the amount of material required, the weight of the addition and other structural needs, labor, and any additional permitting. Homeowners will want to know the estimated size of the second-story addition they need. For instance, the cost to add a room to a house will be less than the cost to add a full second story, since additional structural support, HVAC, plumbing, and electrical systems will be needed beyond the basic construction materials.

The second-story addition cost per square foot works out to about $100 to $500 on average. The larger the second-story addition, the more material and time it will require to complete the upgrade. Since larger additions will take longer to complete, homeowners can expect higher labor costs for extensive jobs. Before starting this project, homeowners are advised to work with the contractor to come up with a basic plan and cost estimate to minimize unexpected costs.

Home Size and Shape

The square footage of the second-story addition is one cost consideration, but the homeowner also needs to keep in mind the size and shape of the existing home. It’s common to install a second story that matches or complements the existing layout of the home, which could lead to higher costs on large homes. 

Also, if the existing layout of the home can’t accommodate the installation of the preferred second-story floor plans, then the contractor may need to make updates to the house, which can increase the overall cost of the job. In this case, homeowners are advised to work with a structural engineer and a contractor to determine the best possible layout for the second-story addition to ensure the occupants’ safety. 

Plumbing and Electrical Work

Adding a second story to the home helps to increase the available living area, but the contractor will need to add appropriate plumbing and electrical lines to ensure that the new addition is both comfortable and functional. Typically, a general contractor will subcontract with a professional plumber and electrician to handle this work. Homeowners can review how much a plumber costs and how much an electrician costs as part of the budget planning process.

Plumbing tasks include running new water lines, drain lines, and vent pipes as well as installing any water-using appliances or fixtures. Adding plumbing will generally cost about $4.50 per square foot. An electrician will run new wires for the space and install suitable electrical outlets, lights, and any other electrical components that are required. These tasks cost about $6 to $8 per linear foot.

HVAC Installation 

Second-story additions are usually ideal for creating extra bedrooms and living areas, but these areas also need climate control for comfort. For this reason, an HVAC professional is needed to install new ductwork so that the second floor of the home can be properly heated and cooled. 

HVAC installation ranges in cost from about $40 to $65 per linear foot. Generally this work is handled by a licensed HVAC technician, just as a licensed plumber and electrician are brought in to handle plumbing and electrical work. Some home builders may have one or more individuals on staff who have an HVAC license, so it’s worth asking who will be doing this work.

Depending on the existing HVAC unit and the size of the home addition, a new HVAC unit might be needed to accommodate the additional square footage. On average, HVAC unit replacement cost is $7,500, though this will vary from one geographic area to another.

Interior Finishes

Beyond the plumbing, electrical, and HVAC work, the contractors will also need to complete a wide variety of interior finishes, from drywall to door installation. The cost for this part of the project can vary significantly depending on the size of the addition, the layout, and the second-story design. 

Larger additions will generally be more expensive, since they require more materials like flooring, insulation, and drywall. The number of windows to be installed will also greatly affect the cost, since double-pane window costs can be significant. The same holds true for doors, which can range greatly in style and cost.

Exterior Finishes

The exterior finishes are just as important as the interior finishes, if not more so, since the exterior of the home protects everything from electrical wires to insulation and wood framework. Depending on the design, the contractor may need to hire a mason to install new brickwork or work with a siding contractor to put in new cedar or vinyl siding. 

The second story will also require new gutters and a new roof to ensure that rain, snow, and ice drain properly away from the home. It might be a good idea to have the contractor touch up the paint on the existing window trim, door trim, and gutter system to avoid a distinct difference between the old and new parts of the home. Alternatively, homeowners could ask about house painting costs if it’s time to refresh the entire look.

Labor and Permits

Labor rates vary based on the profession and location, so while the general contractor may charge 10 percent to 25 percent of the total project cost, an electrician may charge only about $50 to $100 per hour. The overall cost of the job can range significantly based on the type and amount of labor required, so it’s a good idea to have a basic understanding of local labor rates.

The addition of a second story means homeowners will need to acquire a building permit and submit building plans. Permit acquisition is generally handled by the contractor, but homeowners can ask the contractor to ensure that’s the case. Building permits for this type of work typically range from about $1,200 to $2,000, depending on the location and scope of work. 

Geographic Location

The location of the home can impact the cost of materials and labor, so it’s recommended that homeowners get estimates from several reputable companies in the area to better understand the local average cost of adding a second story. Homeowners with properties that are located in major urban centers will typically pay higher rates for both materials and labor.

Rural locations generally have lower costs associated with this type of project since local supply and demand are lower than in densely populated cities. Additionally, if the home is located in an area that experiences severe winter weather, then the materials required to build the home may cost more than what’s needed to build a home in a more temperate area. 

Additional Costs and Considerations

Beyond the upfront cost, there are several additional costs that may be required to complete this project. Whether these extra costs are necessary depends on the property. Homeowners will need to consider these potential cost factors when planning the project and work with a structural engineer or contractor to determine if they are relevant to their project.

Foundation Reinforcement

Many single-story homes do not have a foundation that is designed to support the weight of a second-story addition. Before homeowners add a second story to the home, it’s necessary to have the foundation assessed by a structural engineer. Their expertise will evaluate whether the home can support a second story or if it will need to be reinforced before proceeding. 

Foundation support work will increase the time it takes to complete this job, but it’s essential to have a strong foundation for the home to avoid the risk of collapse. This extra work will typically cost at least $5,000, though the cost may increase based on where the home is located, the scope of work, and the condition of the existing foundation.

Demolition Work

A second story can’t be constructed on top of an existing roof, so the contractors will need to demolish and remove a portion of the current roof before they can build and attach the new second story to the home. Additionally, the contractor may need to open up the walls and ceilings or even remove part of a room to make space for a new staircase and ductwork. 

Removing a roof will cost about $1,250, while replacing the roof once the job is complete can cost about $4.35 to $11 per square foot. If the home has an existing chimney, the contractor may be able to work around it, or they may need to remove it for an average cost of $4,500.

Staircase Construction

Generally, the added second story will need a new staircase for the homeowners to access it. Installing a new staircase for the home can range in cost from about $1,000 to $5,000, including materials and labor. The placement of the staircase should be discussed with the structural engineer and the contractor to determine the best position based on the existing layout and the layout of the new second story. However, it’s important to keep in mind that the cost of this job can increase depending on the complexity of the layout, space available, and custom additions like premium hardwood or carpeting.

Landscaping

Installing a second story is a big project that often involves the use of heavy construction equipment, which can damage the lawn, garden, and nearby plants. Once the job is complete, the house may look great, but the yard could need some attention. Homeowners may want to hire one of the best landscaping companies to restore or improve the appearance of the yard. 

Professional landscaping costs about $4.50 to $12 per square foot, though the exact cost depends on the work required to restore or update the look of the yard. It’s worth discussing landscaping services with the primary building contractor to determine if they offer landscaping services or have a reliable company that they often work with for this type of job. 

Temporary Housing Costs

In most cases, it isn’t safe to stay in the house during the construction of a second-story addition, so the home’s occupants will need to find a place to stay until the job is completed. Temporary housing costs range based on geographic location and the type of temporary housing. 

Short-term rentals can be a good option, though some people may choose an extended stay at a motel or hotel. Another option is to purchase or rent a mobile home, RV, or trailer for the duration of the project.

Types of Second-Story Additions

If budget is a major consideration but extra space is needed, homeowners can decide from among other second-story addition options. Some popular choices include a garage bonus room, a bump-out addition, a full second-story addition, a partial second-story addition, and a second-story balcony. 

Bump-Out Addition

Extending the home into the yard to add an extra room is one way of increasing the available living space, but if the property has a partial second story, the homeowner may be able to add a bump-out addition to the second floor instead of the ground floor. This is helpful if there isn’t enough space on a property to expand the home’s footprint. 

Adding a bump-out is how a contractor creates an extra room on the second floor by building on top of only a portion of the first floor. This project is one of the more affordable ways to add a second story to a house, ranging from just $4,000 to $30,000 in cost.

Full Second-Story Addition

The most costly add-on is a full second-story addition. This involves adding an entire new floor to an existing single-story home, which can basically double the living space available. Second stories are a viable option as long as the foundation and existing structure can support the weight or be upgraded to support it. 

However, since the square footage is larger than that of a bump-out addition, this project will take longer to complete and cost more for materials and labor. Homeowners will typically need to spend between $100,000 and $250,000 to build a full second-story addition, though large homes with high-end materials could cost up to $600,000. In the latter case, homeowners may want to ask how much it costs to build a house to see if the comparison is worth contemplating.

Garage Bonus Room

A popular choice for adding a second story to a house is to build above an existing garage. This type of add-on will cost between $60,000 and $120,000, which is much less than the cost for a full second-story build. Still, homeowners will need to ensure the garage’s foundation and structure can handle the extra weight of a second story. 

A structural engineer can help make an assessment, while a contractor can determine what else the existing structure will require to ensure the job is a success. Some potential tasks include installing additional insulation, vapor barriers, or even extra support beams at the top of the garage.

Partial Second-Story Addition

Homeowners on a budget could also opt for a partial second-story addition, which costs between $80,000 and $300,000 on average. A partial second-story build is a popular choice since the foundation and existing structure do not need to support as much weight, and the overall cost is significantly lower than the cost of a full second-story add-on. 

However, the obvious drawback to this type of addition is that it doesn’t provide the home with as much extra living space as a full second-story addition. It’s also worth noting that while a partial second-story addition won’t weigh as much as a full addition, the foundation may still need to be reinforced.

Second-Story Balcony

The least expensive choice for a second-story addition is to simply add a balcony to an existing attic space. A second-story balcony can provide a unique location where residents can enjoy a more private outdoor living space. This type of addition to the home will cost about $30 to $60 per square foot, in addition to the cost of any doors or windows that are needed.

Benefits of Adding a Second Story

The cost to add a second story can feel prohibitive if the extra space isn’t necessary. Still, if the decision is between adding a second story and moving to a larger home, some homeowners may prefer to invest in their current home instead of purchasing a new property. However, increasing the living space isn’t the only benefit to this major home upgrade, since the addition can increase the home value.

Increased Living Space

The most obvious benefit of adding a second story to the home is the extra living space. By increasing the square footage of the house, the residents can have more space to accommodate a larger family or a mother-in-law apartment. Adding a second story can be a great way to make room for the family rather than selling the existing home and moving to a new property. 

Increased Home Value

The extra living space isn’t just a benefit for those currently living in the home; it’s also a major feature for prospective home buyers who may be willing to pay a higher price to get a home with more space. That’s why adding a second story to the home will increase the overall value of the property. 

The exact amount by which the property value will increase varies widely based on the geographic location, home design, neighborhood, and local housing costs. Homeowners are advised to discuss the project with a real estate professional or contractor before investing in a second story for the sole purpose of increasing home value.

Outdoor Space Retention

Increasing the living space helps to accommodate growing families, but extending the home into the yard reduces the outdoor space available for family barbecues, gardening, and other outdoor activities. Instead, the homeowner can add a second story to the home to gain an equal or greater amount of space for bedrooms, bathrooms, or open living areas without sacrificing the yard. For homeowners in urban areas with small properties, building up rather than out will make the most sense if they want to maintain their outdoor space.

Existing Home Improvements

Depending on the construction company, the homeowner may be able to bundle other home improvements at a reduced rate while adding on the second story. Speaking to the structural engineer will help homeowners determine what upgrades are mandatory before the second-story addition project can proceed. Other home upgrades can be reviewed and scheduled at the same time to minimize disruption to the home and yard.

DIY vs. Hiring a Professional 

Putting in a second story is a great way of adding space to an existing home, but this project isn’t one that can be handled by a DIYer. The scope of work required to assess, prepare, and carry out this work is typically handled by a variety of experienced, trained, and licensed contractors, such as plumbers, electricians, and HVAC professionals.

The best home builders can assess the existing foundation and structure, make changes to ensure the building can support the weight of a second floor, then work with a crew of trained professionals to complete the project. The contractor will also typically handle permit acquisition, so the homeowner can feel confident knowing that the project plan was approved by the local municipality before proceeding. 

However, there are aspects of the job that can be left to an experienced DIYer to help cut down on their house extension cost. Depending on their skill and physical abilities, they may be able to paint the interior of the home, help with cleanup and debris removal, or replace any damaged landscaping. Given that labor generally accounts for about 30 percent to 50 percent of the budget, any work that the homeowner can handle on their own will help to reduce the overall cost to add a second story.

How to Save Money

While adding a second story to a house usually isn’t as expensive as building a new house, this major home remodel project can still cost around $175,000. Given the financial scope of this job, it’s a good idea for homeowners to find ways to reduce the overall cost while still staying true to their intended plan or vision. There are several options to save money on the cost of adding a second floor to a house.

• Choose standard finishes and appliances. Instead of investing in high-end interior and exterior finishes, homeowners can save money by selecting more cost-effective finishes and appliances.
  
• Get multiple quotes. It’s recommended that homeowners research and get quotes from at least three reputable companies in the area to ensure the best price and value.
  
• Go with a simple floor plan. Complex floor plans will take longer to complete, driving up labor costs for the project. Opting for a simple floor plan reduces the overall cost.
  
• DIY some parts of the project. While the average DIYers won’t be able to complete a second-story addition project on their own, they may be able to take on other tasks to save on labor costs. Painting and installing new landscaping are possible DIY projects.
  
• Stay with family or a friend. During the home upgrade project, it’s more cost-effective to stay with family members or a close friend instead of paying for a short-term rental or hotel.

Questions to Ask a Pro

Adding a second story to a house isn’t a common job, so it’s important to find a reliable contractor who will be able to answer a homeowner’s questions and concerns. It’s advised that homeowners ask lots of questions before, during, and after a major construction project.

• Are you licensed, bonded, and insured? 
• Do you have references I can speak with and a portfolio of work?
• Do you carry workers’ compensation and liability insurance?
• How much extra living space will I get with a second story?
• Will you provide an estimate of the project cost, including design, installation, and materials?
• Who will inspect my foundation for structural integrity?
• How long will the addition take to complete?
• What building permits and paperwork are required for this project?
• Who is responsible for permit acquisition?
• Will everyone working on the project be fully licensed and have all the relevant safety certifications and insurance?
• Will you subcontract out any part of the project?
• What type of roof should I install on the second story?
• What structural changes need to be made to my existing home to support a second-floor addition?
• Will the second-floor addition require any changes to my existing foundation?
• Will the project require any changes to my existing plumbing and electrical systems?
• How will adding a second story impact my heating and cooling costs?
• What design and style options are available for my home?
• Can I remain in my home during the project?
• How will you protect the rest of my home and property from damage during the construction project?
• Are there any changes I should consider for my main floor while my home is undergoing a second-story addition?
• What payment plans are available?

FAQs

Home additions can greatly increase the amount of living space available for the homeowner or residents, allowing families to grow without needing to move. However, the process to add a second story to a house isn’t a common one, so it’s a good idea to find out more information about the process to gain a better understanding of the home addition cost and project scope. Answers to some of the most frequently asked questions about adding on to a house can provide clarity about this project.

Q. Can my foundation support a second story?

One of the problems homeowners experience is that most single-story homes do not have a foundation that is strong enough to support the extra weight of a second story. Before homeowners start this project, it’s recommended (and sometimes required by local municipalities) to hire a structural engineer to assess the foundation and determine what changes need to be made to ensure the foundation can support a second story.

Q. How long does it take to build a second story?

Room additions on the ground floor can be completed in just a few weeks, but adding an entire second story to the home will typically take from about 6 to 12 months, depending on the extent of the work required. For instance, extra time won’t be needed to shore up a foundation capable of supporting a second story. But if the foundation needs work, then even the best custom home builders will take longer to complete the addition. 

Q. Is it hard to build a second story?

Adding a second story to an existing home is a difficult job that falls well outside of the capabilities and expertise of the average DIYer. To ensure the work is completed safely, this project is best entrusted to a crew of professionals who specialize in home additions. If a second story is haphazardly added to an existing single-story home, there is a chance of partial or full collapse, faulty wiring, leaky plumbing, and many other problems. Hiring a general contractor is the ideal solution to ensure a high-quality result.