What Is Cheaper — Adding a Second Story Addition or a Ground Floor Addition?

You definitely need more space in your one-story home, but you love the location and don’t want to move. Your options are basically building up by adding a second story or building out by putting in an addition. While cost is always a consideration when making a decision, the nature of your space needs will also dictate the best way to move forward.

If you have a growing family and too few bedrooms or baths, building up or out are both good options. However, if your primary needs concern more recreational room, such as a den or playroom, then it may make more sense to build an addition than to add a second story. That’s because you must concern yourself with your home’s resale value, and most people prefer a ground floor family-type room rather than one based upstairs. Traditionally, the second floor is the province of bedrooms and not the place where you might entertain guests. If you want a bigger kitchen, it certainly doesn’t make sense to put it upstairs.

Your property’s size and shape will play a big role in your decision. If you have a large backyard, an addition won’t have as much of an impact as it would if your rear yard is relatively small. In some cases, you won’t have a choice, as your backyard is simply too small to accommodate the kind of addition you desire. Consider whether you may want to make other improvements to your property in the future, such as installing a pool. Many homeowners realize they can have a buildout addition or a pool but not both. If you really like your yard, building up makes more sense.

Before making a decision, contact your municipality about the zoning laws in your neighborhood. Your town likely has ordinances regarding setbacks, which limit how close you may build next to your neighbor’s property line. By the same token, a town may also have laws on how high you can build a home, but relatively few municipalities preclude building a second story per se. If your home is in a historic district or planned community of one-story homes, you may not have the option to build upward. However, if you have your heart set on an addition and your plans don’t meet the setback requirements, you may have the opportunity to go before a zoning board of adjustment and make your case as to why the board should grant you a variance and allow you to build. Since your immediate neighbors are notified of your plans, it may prove best to discuss your plans with them ahead of time to see if they will lodge an objection.

In general, it is less expensive to build up than out, but that comes with a lot of caveats. According to HomeAdvisor, the average cost for building additions is between $80 to $200 per square foot without regard to whether it is up or out. While it is usually cheaper to build up than out, that’s just the actual construction expense. When you add another story to your home, you will probably have to relocate until the work is complete, as the contractor must remove the roof. Unless you have friends or family willing to put you and yours up for a while, you’ll have to rent another dwelling or stay in a hotel during this period, and those costs are considerable. If you’re building out, you will have to deal with the dirt and disruption of construction, but you can generally stay in place.

Costs also vary depending on exactly what the contractor must do. An addition usually costs more because the builder must perform excavation work and install a new foundation. When construction is near completion, the contractor must open up the exterior wall of your home so the old and new are joined together. However, if you decide to build up, you have to make sure your current foundation is strong enough to support another story. If the foundation requires retrofitting, the expense includes removing your existing walls, which will raise your costs substantially. Keep in mind that adding another story means adding a staircase, which will take up precious floor space on your first floor.

One of the least-expensive additions is a sun room, which can double as a comfortable playroom or family room. The average prefabricated sun room costs about $16,315, according to HomeAdvisor. If you live in a warm climate, you don’t have to worry about heating the sun room, and if you live in a colder area, you can save money by not heating this room and only using it during three seasons.

If your home has an attic, an attic conversion into a bedroom and bath or a family room may give you the space you want at a lesser cost than either building out or adding a true second story. While you may have to replace the roof if it is old or leaking, that often means just putting a new roof on top of the old roof, which a contractor can usually accomplish in a couple of days. Expect to pay between $50,000 to $65,000 for an attic conversion. Unlike a second-story conversion, you won’t have to vacate the premises while work is happening.

The only way to know whether building up or out is less expensive is to go over the numbers with your contractor or architect. Figure that the latter will cost between 10 and 17 percent of the budget, but it’s important to hire an architect in most circumstances to ensure the addition complements the house. While an architect is necessary for a build up, if your addition consists of just one room with a one-door entry to the main house, a general contractor should fit the bill. If you go that route, ask to see similar work the contractor has done. You don’t want to end up with an addition that looks tacked on to the rest of the house and is aesthetically unappealing.

Compare the costs of prep work. While excavation costs average $2,559 per HomeAdvisor, if your addition is larger than average, you’ll end up paying more. Concrete for footings is approximately $75 per cubic yard, while support beams and roof trusses run between $15 and $30 per square foot. Then there are the individual decisions, such as what type of flooring you want to install. Vinyl flooring is the least expensive, but it’s far less attractive than costlier wood, ceramic tile or natural stone.

When it comes to costs, you should also factor in how much an addition will add to your home’s value. You will rarely get a 100 percent return on your money for an addition, meaning that if you spend $75,000, you can't necessarily add that amount to the value of your home. However, some additions pay back more of what you spent than others. Add a master suite and you could get 63 percent of your investment back when you sell. A new bathroom adds about 53 percent, and a sunroom adds just under 50 percent.