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What to Know Before Adding a Second Story to Your Home

If you live in a single-story home, at some point you may find yourself thinking about more space. While you could sell your house and buy a larger one, there may be more appeal to staying in your house and adding onto it. Read this guide to learn more about what it takes to add a second floor to your house.

A two story home iStock

When building an addition, many homeowners choose to go up–adding a second story—which has advantages. You may not have to add a new and expensive foundation. Also, you won’t have to worry about zoning setbacks and getting too close to your property lines. You’ll probably also increase the market value of your home. But adding a second floor to any house is a big project, so before you start hunting for a builder, give ample thought to the details.

What to Consider Before Adding a Second Story


Call your local building department and learn about the relevant zoning regulations in your neighborhood. For instance, there may be height restrictions that prevent someone from blocking their neighbor’s view, or there may be a cap on a home’s square footage. If you have a small or older septic system and want to add a bathroom, you may be required to increase the system’s capacity.


There are a few options for adding a second story.

  • Option 1: Remove the roof, frame the new second floor over the existing footprint, and build a new roof. Sometimes the roof can be lifted off intact with a crane and then brought back when the new walls are framed, which may save you money.
  • Option 2: Add a smaller second floor over a garage or addition, rather than over the entire house. The advantages to this method are a potentially lower cost due to the smaller scale and less disruption to your life at home.
  • Option 3: Go modular and have the new second floor built off-site, then brought to the site and craned into place. This option may be the least invasive because the on-site work time is diminished; it’s also likely to be less expensive than building on-site. There are size limits to modular units. However, that may not work with the layout of your existing house.

No matter what option you choose, make sure you have the right style for the addition. This is where the designer or architect earns their keep. It’s one thing to recognize your spacial needs—two bedrooms and a full bath, for instance—and quite another to integrate the exterior shell of those spaces into the scale and style of your existing house.

Spend time considering how the new addition will blend into the neighborhood. Your neighbors will appreciate the thought.

Find a builder

When it comes to choosing a builder, do your research. Experience counts. A builder who’s done similar projects will be able to recognize and solve problems before they become expensive. Local is usually better—increased travel time for the crew can lead to delays, and they may be less able to respond to problems during off-hours. A local builder also has a vested interest in maintaining a good reputation in the community. During the interview process, ask for recent previous customers’ names and talk to them about their experience with the builder.

Foundation check

The next step is to hire a structural engineer to evaluate your foundation. This is a critical step—the foundation was built to support a single story, and now you’d like it to support potentially twice that mass. If the foundation or the soil supporting it isn’t up to the task, you’ll either have to reinforce the foundation or give up the idea altogether.


You’ll need to obtain construction permits for from your local building department. The permits should cover the engineering, zone approval, framing, seismic considerations, as well as the work of subcontractors (electricians, plumbers, etc.). Typically based on a percentage of the project’s total cost, the national average for obtaining permits is about $1,300.

Homeowners can obtain the permits, but that task usually falls to the general contractor. Once you have the permits, town or municipal building inspectors will periodically visit the site to ensure that the construction conforms to applicable building codes.

Where will you live?

Unless you opt for a partial addition built over a non-essential part of the house, like the garage, or you decide to go modular, you and your family may find yourself living somewhere else for the duration of the construction. Think months, not days. If you stay, you could be living without a roof, electricity, plumbing, and HVAC for an extended period, and then there’s the daily invasion of the building crew, dumpsters in the driveway, etc. Unless you can stay with family or friends, living in a hotel or rental property will add to the overall cost.

Cost to add a second story

There are lots of variables in play when it comes to trying to estimate the cost of an upper addition. You may have to hire a structural engineer—in addition to an architect and contractor, or design/build firm. How many square feet will you add? Will the addition have a bathroom? High-end finishes? You’ll need a new set of stairs. Do you live in a big city, where costs are typically higher, or out in the woods, where prices are typically lower? If you live in an earthquake zone, seismic considerations may require extra materials and labor. And as mentioned, you may have to rent a living space until the project is complete.

All these factors will influence the cost. Rest assured, your addition will be expensive. According to resources such as and, even the least expensive addition will cost over $100 per square foot, and most will cost somewhere between $300 and $500 per square foot. Or more.

The one thing that should ease your conscience is to think of your second-story addition as an investment in your home and your post-construction life. Adding a second story will not only increase your home’s space, but it may also increase its resale value. If you have the market in mind, it’s always a good idea to check with a realtor to ensure that your investment will likely translate into a higher resale price.

Final tips

If you choose to stay in the house during construction, ask the builder to construct a set of temporary stairs on the exterior that will help ease traffic through the house.

If you have an older home, you may find that parts of the existing house, such as the framing and electrical and plumbing systems, must be upgraded to be code-compliant. The façade may need an upgrade as well—the old windows may not be visually compatible with the new windows on the second floor.

You may be able to defray some costs by taking on some of the later-project work, such as drywall or painting.

Be open to alternatives in the design process. Your architect or builder may have ideas that could save you money.