How much does a home addition cost?

You’re feeling pinched in your house; you need more space. Or, you love your house — but you still need more space. A home addition could be the solution. It’s a thought many homeowners have had over the last two pandemic years, and given the shortage of housing and skyrocketing property prices, adding rooms to residences has gotten more common than ever — even though they are some of the most expensive and time-consuming of home renovations.

The cost of a home addition typically ranges from $21,000 to $74,000, putting the average project right at $46,000. But really, you can expect to spend anywhere from $5,000 to $150,000 depending on the type and size of the addition, the materials used, labor and your location, according to HomeAdvisor. Here’s how the prices play out, what contributes to the costs, and some tips on financing and saving money on the project.

How much do home additions cost?

Since “home addition” can encompass a tremendous variety of things — anything from a single small room to an entire story or wing — generalizing about cost is tough. Generally the size of the addition (the number of rooms or floors involved) and the nature of the addition (the types of rooms) are the key factors, along with the building materials and the types of contractors required. Other factors that often influence cost include design of the house, the surroundings and zoning requirements. Because of these variations, homeowners with two similar properties undergoing the same additions can end up with significantly different tabs.

Depending on all the above, a home addition can cost as low as $25 per square foot or as high as $400 per square foot. Interestingly, ground-floor rooms cost less per square foot than second-story rooms: $80 to $200 vs $100 to $300, according to Angi.

Online calculators can offer a rough idea of what you’re in for, but of course for the most accurate quote, you’ll need a professional builder’s estimate, customized for your particular project. Also keep in mind that unforeseen expenses may pop up, and for this reason, it is a good idea to budget about 20 percent extra for the home addition.

What affects the cost of home additions?

Getting down to cases, what variables play into the cost of a home addition?

The size and extent of the house addition

Home additions are typically priced per square foot. However, while size does matter, calculating the price by square foot alone (which is what a lot of online calculators basically do) will likely result in an inaccurate estimate. A 100-square-foot addition will not cost double what a 50-square-foot addition costs, but just increase the price by one-third.

Why? Because no matter what its size, a home addition often involves the same amount of work for the contractors, from initial design to final clean-up. Far more significant is the complexity of the project.

Basic home additions — that is, closets or bare-bones rooms with rudimentary electrical wiring — generally cost the least because they are easier and quicker to complete. Once plumbing gets involved, the cost begins to climb. And it continues to do so with each additional detail, like windows or doors or walls. The more complex or luxurious these features, plus furnishings and appliances, the higher the costs. 

The house addition’s location

Indoor and outdoor obstacles need to be removed or relocated to make room for an addition, which in turn drives up the project cost. Where do you plan to build your home addition, and what’s there right now? Think about landscaping, HVAC systems, electrical wiring and even hidden features like underground pipes.

The house addition’s building materials

Most people who build home additions want the new parts of their homes to match the existing residence. So, you’ll have to pay for whatever materials were originally used to build your house — and if that means wood siding, triple the cost of  vinyl siding, c’est la vie. You’ll also likely need to extend the roof to cover the addition, and this too should ideally match the original.

Contractor costs for the house addition

From architects and engineers to painters and roofers, a lot of labor costs, and different types of laborers, get involved in home additions. Relating to the complexity of the job, the more skilled or specialized the sub-contractor, the  more expensive their services will be (think plumbers and electricians). All told, contractor labor costs make up about 30 to 50 per cent of a total budget, according to Angi. Make sure to get quotes from at least five different general contractors before you make up your mind. 

Local zoning laws

Every municipality has different zoning laws for home additions, and your home addition cost could go up if you need to obtain permits and meet certain compliance standards. Water drainage, septic systems and electrical wiring are just a few examples of components that could be regulated. A qualified local builder will be able to inform you about the requirements in your area.

Home addition costs by room type

Another way to calculate costs of a home addition is by the type of room. For example:

• Simple room: The cost of adding a spare room or simple living room up to 10×10 square feet could be between $8,600 and $15,500. Increase the square feet, and the cost will quickly go up, anywhere between $17,000 and $60,000.
• Master bedroom: Because they usually have an attached bathroom and closets, master bedroom addition costs can quickly skyrocket. For a master bedroom between 200 and 400 square feet, the expense could be as low as $59,000 or as steep as $100,000. The more luxurious the project, the more money it involves; but these “master suites” recoup their cost and increase a house’s value by around 55 percent, the National Association of Realtors’ “2021 Cost vs Value Report” says.
• Bathroom: Building out a bathroom can cost between $18,000 and $47,000. Although it is one of the most expensive rooms to add or remodel, according to the National Association of Realtors, it also increases the resale value of the house by more than 50 percent.
• Kitchen: The cost of adding a kitchen mostly depends on the square footage and the price of the appliances. For a standard, 10×10 kitchen with low- or mid-range appliances, the cost can be $25,000 to $43,000. Luxury kitchens with high-end appliances can cost as much as $100,000.
• Second story: Adding a second floor to a home is almost like building an entire house from scratch. The cost can run $300 to $500 per square foot, especially since replacement of the roof is going to be involved. Depending on how many rooms are being built, the total expense can easily slide into six figures.

Tips for saving on home addition costs

If you’re worried about how much house additions cost, there are plenty of tricks you can use to bring the final price of a new room down, including:

• Converting or extending an existing space, instead of a building entirely new one.
• Taking advantage of tax refunds/rebates for energy-efficient construction and features
• Using less-expensive materials: many synthetics or pre-fab materials quite convincingly sub for “the real thing” 
• Avoiding fancy customizations.
• Identifying jobs or finishing touches you can complete on your own.
• Shopping around for the best interest rate on financing.

How to finance the cost of your home addition

Given how expensive home additions are, you might need to borrow to pay for the project. Even if you have the means to cover your home addition, it is smart to consider financing options. The following are some of the loans available to homeowners. 

Home improvement loan: Also called a personal loan, it works like any standard loan: Borrow a lump sum, on which you have to pay interest for the repayment period that you choose. If your expenditure is not enormous and you only need a fixed sum of money for your project, you could take out a home improvement loan and repay it over a period of 12 to 60 months.

Home equity loan: This option works like a second mortgage, where you borrow money using your house as a collateral. A home equity loan has a fixed interest rate and a set repayment period, and if you itemize the interest, it may also be tax-deductible.

Home equity line of credit: Although a similar concept as a home equity loan, a home equity line of credit (HELOC) acts like a credit card, where you can borrow against it, repay the loan, and then borrow again, up to a certain limit. It also has variable interest rates.

Next steps in your home addition

If you love the location of your house but wish you had more space — or different sorts of space — a home addition may be a great option. Before you commit to one, determine the scope of your project. Think about what type of addition would be best for your lifestyle needs.

Then, secure the ideal contractor and source of funding for your situation. Shop around for the best home improvement loans. Also, look at your budget and the costs of borrowing. Don’t borrow more than you can comfortably afford, and be sure you can comfortably repay the debt.

As your project gets started, remember to be patient and keep in mind that there are likely to be roadblocks and delays along the way.

Home additions don’t come cheap — the most elaborate, multi-room projects can easily exceed $100,000. Still, they’re a lot less expensive and less hassle than buying and moving to another place. And when done right, a home addition can make a house feel brand new. 

Learn more:

• The top 4 home renovation mistakes — and 4 tips for avoiding them
• How much does it cost to finish a basement?
• How much does HVAC installation cost?