The average U.S. homeowner spends $48,000 on a home addition, but the cost ranges from $20,900 to $72,600, depending on the type of room and the amenities it has.
A room addition costs $48,000 on average, but ranges from $20,900 to $72,600, depending on materials, labor, and room type. The cost can also vary by location and whether you choose to do some of the work yourself or hire a contractor.
Adding a new room not only gives you and your family more space to live in, but it can also increase your home's value. However, room additions can get pretty pricey, so it's helpful to create a realistic budget before taking on this project.
Your new room's size is one of the biggest factors that affect the overall cost. Basically, the bigger the room you want to add on, the more you can expect to pay for the project. Here's a breakdown of average prices by square foot.
| Room Size | Average Prices |
|---|---|
| 20’x20’ | $32,000 – $80,000 |
| 12’x12’ | $11,520 – $28,800 |
| 10’x12’ | $9,600 – $24,000 |
| 400 sq. ft. | $32,000 – $80,000 |
| 500 sq. ft. | $40,000 – $100,000 |
| 600 sq. ft. | $48,000 – $120,000 |
| 1,000 sq. ft. | $80,000 – $200,000 |
Different rooms have different installation requirements, which can tack onto the cost of your addition. For example, if you're adding a primary suite with an attached bathroom, you'll need to pay extra for things like bathroom plumbing, which typically costs around $1,500 to $4,000.
Here's what you can expect to pay, depending on the type of room you want to add.
A bedroom addition costs $50,000, on average, depending on its size and features. Larger bedrooms with more space, windows, and walk-in closets will be on the higher end of the range. Small bedrooms for kids or guests will be much easier on your wallet.
Adding a new bathroom costs $22,000, on average, but it significantly increases the value of your home. Depending on where you live, you can expect a 47% to 67% ROI on your bathroom addition. A half bathroom, which includes only a sink and toilet, takes up much less space and is a more affordable project, costing $4,200 to $12,000.
The cost to build a primary bedroom with a bathroom ranges from $30,000 to $100,000, but they can vary quite a bit depending on the details. For example, if you add a particularly large suite or high-end features, like custom cabinetry and marble countertops, the project can easily cost over $100,000.
A new kitchen installation costs between $35,000 and $95,000, with average prices around $65,000. Certain features like islands and appliances account for a lot of that price, so it’s possible to cut expenses in many ways.
A bump-out addition expands a current room and often adds new amenities. Bump-out additions cost $4,000 to $30,000, depending on the amount of space you’re adding. Because there’s little electrical work and rarely any plumbing, bump-outs are more affordable than many additions.
Are you looking to create a separate dining room or build a new version of your current dining room? Expect to pay between $3,000 and $50,000. High-end lights or chandeliers, a wet bar, and other amenities will add significantly to the price.
Finishing a basement refers to converting a basement space into a fully livable room complete with lights, heating, and more. The cost to finish a basement ranges from $15,000 to $75,000, depending on the amount of work you need to do. A “half-finished” basement will take notably fewer materials, for example.
Finishing an attic is similar to finishing a basement, although the addition tends to be simpler and less expensive. Most owners finish an attic to turn it into an extra bedroom, office, or lounging area. Expect to spend between $10,000 and $50,000 on the cost of finishing an attic.
A garage can serve many purposes, but it’s often an excellent spot for a game room, extra bedroom, or office. It’s also a lower-cost project than many kinds of additions, with less wiring and plumbing work needed. Converting a garage to a room costs between $6,000 and $27,000.
Adding a bonus room above the garage costs around $115 per square foot, with the average project amounting to about $45,000. However, the cost varies based on factors like whether you need to build a staircase or change the structure of your existing garage. Significant structural changes can add $10,000 to $40,000 or more.
Most people pay between $5,000 and $7,000 on the cost of adding a laundry room to their home. However, if you decide to upgrade your appliances, replace or install a sink, or install more shelving, the cost can reach as high as $10,000 or more.
Thanks to their small size and nonexistent plumbing requirements, mudrooms are often the least expensive rooms to add on. A 36-square-foot mudroom at the entrance of a home or a new entryway costs around $3,600 to $7,200, depending on the type of flooring and storage you add.
Depending on construction, a window-filled sunroom can serve as a play area, a second living room, or even a small indoor greenhouse. Expect the average three-season sunroom to cost between $10,000 and $40,000.
Adding an in-law room or rooms to your home can require numerous special considerations, including privacy and access concerns that could increase the project's cost. Adding an in-law suite costs $44,000 to $100,000, depending on their size and complexity.
Home addition labor, materials, and overall scheduling are managed by a local home addition general contractor. On average, hiring a general contractor will cost around $300 to $500 per day in addition to the material cost of the project. However, some contractors will charge a percentage-based fee—often 10% to 20% of the total project cost. The general contractor will be the one to provide an estimate of the costs, go over the details, and schedule the work. They will often have an assistant or team, which incurs additional costs.
The average room addition also requires more specialized work, including plumbing, roofing, and wiring. General contractors often hire subcontractors to complete these steps. Many room additions may require the services of an architect during the planning stages, which costs $2,000 to $8,400.
[For a home addition], we charge piece-by-piece for the project, then we add our profit and overhead. For example, lumber for the project, permits, demolition, electrical, plumbing, and drywall. I add them up and then add our profit and overhead. On smaller jobs, we work by the hour and then add the material on top of that.
| Room Addition Cost Factors | Average Costs |
|---|---|
| Permits | $150 |
| Demolition and site prep | $1,300–$5,100 |
| Foundation work | $4,200–$13,200 |
| Framing | $6–$10 per square foot |
| Roofing | $80–$100 per square foot |
| Support beams | $1,150–$4,600 |
| Doors | $1,000 |
| Windows | $235–$2,500 |
| Drywall | $1–$3 per square foot |
| Flooring | $1,500–$4,500 |
| HVAC | $1,150 |
| Electrical wiring | $2–$4 per square foot |
| Plumbing | $1,000–$10,000 |
When budgeting for a room addition, there are many potential costs to consider, including expenses for architectural services, foundation materials, and flooring.
Unless you're building your house addition yourself, your contractor will be responsible for obtaining and meeting the requirements for the permits necessary for your addition, and its cost will be part of your contract. The cost of building permits varies by location and project size and ranges between $150 to $2,000 in most situations.
It usually costs around $1,300 to $5,100 to excavate, demolish, and prepare a construction site to build on.
Building a first-story addition requires laying a new foundation, which can cost you around $4,200 to $13,200.
Even a small room addition will have a home renovation contract that includes the cost of framing the new space. Framing costs vary by project complexity and how the new structure will tie into the old one. Expect an average price of between $6 and $10 per square foot of the addition for framing.
It usually costs around $80 to $100 per square foot to lay a new roof, so the bigger your addition, the higher your roofing costs.
Your walls need support beams to remain structurally sound, and these beams usually cost around $1,150 to $4,600 to install.
“Doorways from the existing house to the new space will need structural enhancement, as most external walls are load-bearing walls,” says Bob Tschudi, an Expert Review Board Member and general contractor. “As with any such change, it’s always good to consult with a structural engineer.”
Doors cost around $1,000 to purchase and install, while windows range from $235 to $2,500, depending on the style and any customization.
For walls to look like, well, walls, they need drywall, which costs around $1 to $3 per square foot.
The cost of adding flooring to a room varies quite a bit by type and material, but it usually ranges from $1,500 to $4,500. Wood flooring typically costs the most, while vinyl and linoleum floors typically cost the least.
If you want to regulate the temperature of your addition, then you'll need to extend your existing HVAC system, which costs about $1,150, on average. “Your HVAC contractor can tell you if your existing HVAC system can condition the new space,” says Tschudi. “If not, you would need a larger HVAC unit or install a separate HVAC or a heating and cooling mini-split system in the new room.”
Part of nearly any home addition cost is electrical installation. Expect to spend between $2 and $4 per square foot for wiring outlets and lighting. If reworking the home's existing electrical system, such as replacing an outdated service panel, is necessary to meet building code for the new room, expect an average additional cost of $1,150.
If your room addition also must include the cost to add a bathroom in the new space, expect plumbing installation prices to vary widely depending on the complexity of the addition and how it ties into the home's existing system. Plumbing costs will range from $1,000 to $10,000 to add a bathroom.
Adding a room is a complex and time-consuming job that should be handled by a professional. However, if you have the necessary tools, skills, and experience, you can save roughly 30% to 50% of the project's overall cost by DIYing. This comes out to a savings of about $50 to $100 per hour in labor costs.
Another benefit of doing the work yourself is that you can create the space exactly as you envision it, with all the personal touches and details.
Building a room addition, or hiring a home-addition contractor near you, can be a significant investment in both time and money. However, there are several ways to save cash on building your addition to help meet a project budget.
If possible, save up for the project to pay at least some of the costs without financing to avoid long-term interest charges.
Perform some of the demolition and finishing work yourself, such as painting and trim.
Stick to your pre-determined budget for fixtures and features. Obtain at least three price quotes from various contractors and avoid extremely low bids, as they're seldom as good of a deal as they appear.
Reuse items from your existing home if demolition is part of the plan, or get second-hand fixtures and features from re-use outlets at bargain prices.
If you're supplying some of the project's materials, shop around for sales and discounts at multiple retailers.
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Some people start the process before finding out if the addition is allowed by the municipality or other governing authority, such as a homeowners’ association. Tschudi advises that even if you have the land to extend your house, there can be restrictions, like easements, flood zones, HOA rules, historical preservation, and septic system tank sizes. Many homeowners start the planning process by having the property surveyed, which costs from $300 to $600.
The short answer is yes. Room additions almost always increase a home's value. But just how much they increase it varies by the materials you choose, the type of room you build, and other factors. For instance, adding a sunroom will yield you a 49% return on your investment, while adding a primary suite results in a 63% return on your investment.
First and foremost, you should consider whether you have the time and money to add a room to your home. Additions can be costly, especially if you hire a general contractor, so it helps to make a realistic budget.
If you decide to tackle the project yourself, just make sure you have the time and resources to finish it. Other factors for consideration include the type of room you want to add, how much that room will contribute to your home's resale value, and how much you're willing to spend on details like various finishes and materials.
