How Much Does a Home Addition Cost to Build?

• Typical Range: $20,835 to $72,552
• National Average: $46,498

Ready to add some space to your house? Home additions are a popular way to maximize an existing property by adding new rooms to the floor plan. You could build another bathroom, bedroom, living space, garage, or even an entire apartment. Each kind of room comes with its own complexity, so home addition costs have a wide range of prices: $20,835 to $72,552, or an average of $46,498. The total price depends on the kind of space you’re adding, the size, complexity, materials, and labor. Home additions make a great investment in your home, and you can often expect a significant return on your investment. If you’re committed to adding on to your house, but you’re wondering about home addition costs, then read on for the cost of home additions—and how to save money.

Factors in Calculating Home Addition Cost

Home additions typically cost more than a single-room remodel or renovation since there are more factors to consider, particularly if you’re adding more than a single room’s worth of space. If you add space on the ground floor, contractors will need to add a new foundation plus all the standard building materials from wood to shingles. While some additions can be a simple add-on to the back of the house, others are much more complex and require an architect to ensure the existing home doesn’t lose structural integrity. Knowing the location and style of addition you want to add will help guide the first steps of the budgeting process.

Size and Scope of the Home Addition

As is typical for any construction project, much of the cost is determined by the total size. The bigger the space, the higher the price. According to HomeAdvisor, home additions cost $80 to $200 per square foot. Adding a spare room is a common project, and the average cost ranges from $32,000 to $80,000 for a 20-foot by 20-foot room, with the higher end including more customization or luxury fixtures.

Labor and Permits

There’s no way around most labor costs on a large project like a home addition. They tend to make up 30 to 50 percent of the total price. You’ll be paying for skilled laborers like electricians, roofers, siding contractors, drywallers, and painters, depending on the type of space being built. Additionally, home additions are significant projects that require building permits from local authorities. Obtaining a permit will be the first step a general contractor takes to make sure the project can proceed as planned. Expect to pay between $400 and $1,850 for permits.

Materials

The range of materials used for home construction is vast: concrete, wood framing, drywall, paint, electrical wiring, ductwork, roofing materials, plumbing, and more. Beyond these basic materials, include any customizations and accents like flooring, exposed beams, lighting, fixtures, windows, and doors into your budget. The cost to build a garage will also be different since you may need fewer common materials for an unfinished garage but then have to include a big-ticket item like an automatic garage door. Each material comes with an associated cost that is based on current market prices for the region.

Geographic Location

Home construction costs vary from state to state and city to city. Homes with the same square footage could have a valuation discrepancy of millions of dollars in some coastal urban areas compared to others cities farther inland. Home addition costs will be reflected by the home’s current valuation and the cost of labor and materials in the region. A booming construction market tends to push prices higher, too.

Building Up vs. Building Out

There are two directions you can build when adding onto a house: up or out. Building up tends to be less expensive and could be your only option on a smaller property. If you have an existing garage, building on top of it is more economical since the foundation is typically built to withstand more weight. Building out is often more expensive since a new foundation will need to be laid, and there may be structural issues to address to make sure the roofline and walls remain strong with the new addition. Talk with your contractor about which option works best for the property and budget.

Site Preparation, Excavation, Demolition

No matter where you build the add-on, the contractor has to prepare the site for new construction. This could include demolishing part of the roof or house, landscaping, or concrete that’s already on the ground. It costs $1,276 to $5,024 to prepare a site for new construction.

Architectural Services

If you’re wondering, “How much does it cost to build a garage?” then be sure to also factor in an architect’s services. Adding a significant structure to your house should look intentional and match the current style and design to maximize ROI (return on investment) and curb appeal. For $2,020 to $8,400, an architect can draft an updated blueprint that includes all structural considerations and the aesthetics of the home addition. Permit approval will also require these blueprints.

Contractor Services

Hiring a general contractor may seem daunting and expensive, but the peace of mind knowing they are capable of handling a complex project is worth it. General contractors usually cost $150 per hour, and their total cost can add up to approximately 10 to 30 percent of the final bill. General contractors will obtain permits, hire and coordinate subcontractors, purchase materials, and ensure the job proceeds on schedule.

Cleanup

Home additions generate quite a mess despite efforts to minimize the dirt and debris. As part of the construction process, the contractor should include time and effort for cleaning up the project. This should consist of hauling away any debris or extra materials and cleaning up dirt, dust, and debris from the floors, walls, counters, and windows. It usually costs $550 for a post-construction cleanup.

Additional Costs and Considerations

Most of the additional costs for home additions are made up of essential materials. The difference in total price will be based on how much of each material is required for the size of the addition, as well as the quality of the material.

Foundation Materials and Installation

Adding a foundation for a home addition is a critical first step that can’t be skipped if building out. On average, the materials will cost $400 to $700 for 100 square feet, but the installation will cost $4,000 to $12,000. Much of these costs will be based on the size of the foundation. To find out how much it is to build a garage, talk with a garage contractor to find out if you’ll need to reinforce the concrete or build it thicker for your vehicles.

Roof Framing and Materials

A waterproof roof makes for a livable space that protects from the weather, so don’t skimp on these materials. Roof framing costs $700 to $900, and roof materials cost $500 to $5,000 for 100 square feet. You’ll want to use the same material as your existing roof, with the closest color match possible. Adding shingles will cost between $80 to $100 per square foot, but steel roofing costs between $75 and $350 per square (10 feet by 10 feet).

Siding and Trim

Many homes use vinyl siding to complete their exterior with a uniform look, so if your house has siding, you’ll need to budget for adding siding to the new construction. Vinyl siding averages $4 per square foot, and the trim costs $2 to $5 per square foot.

Drywall Ceiling and Walls

While in some climates you could install an unfinished garage without drywall, every other home addition will require drywall to cover up the insulation and electrical wiring and create the dividing walls between other rooms. To drywall 100 square feet, expect to pay $400 to $600. It costs about $1 to $3 per square foot to install drywall on the ceiling and walls.

Insulation

Any structure considered a habitable space (not a garage) is required to have insulation. The type and thickness requirements are based on local building codes that a contractor will know. It costs $2 per square foot to install insulation. Adding more or thicker insulation will cost more, and using blow-in insulation typically costs at least $2.88 per square foot.

Doors and Windows

Adding natural light is a common preference when adding to a house—but it comes at a cost. Windows are a fast way to increase the cost of an addition, whether by their size or number. At a minimum, it costs $235 to install a window, but you could spend up to $2,500 for a customized window. Doors typically cost $1,000 to install, but hollow interior doors are less expensive than heavy exterior doors or glass doors. In both cases, adding a heavy frame or molding will add cost as well.

Electrical

Electrical wiring is essential for all home additions to make sure you have light and power for all those electronics. An electrician can wire the room to spec for a rate of $40 to $100 per hour. They’ll make sure the house is built to code to pass inspection when the construction is complete.

Flooring

Whether you’re considering the cost to add a bathroom or a bedroom, you’ll need to decide on the type of flooring you want to install. Linoleum and vinyl are the least expensive options, but you could also choose tile, carpet, or hardwood floors. The price ranges widely from $3 to $20 per square foot, so choose the option that fits your budget.

Plumbing

You might not need to install plumbing if you’re only adding on a bedroom or office; however, bathrooms, kitchens, and in-law apartments will need some plumbing installed to be fully functional. Plumbers typically charge $45 to $200 per hour to install plumbing and fixtures for a bathroom or kitchen.

HVAC

Adding an HVAC system (or extension from an existing system) is necessary for habitable spaces. A garage may not need heating and air conditioning, but a bedroom will. Expect to pay around $1,150 to install new ductwork and vents for an add-on, but that price will increase if you need to add a new zone to the system to accommodate a significant addition.

Landscaping

After the construction is done, you’ll need to turn your attention to the landscaping around the addition. Heavy equipment may have damaged more of the grass than expected, so consider replacing it with new sod to freshen up the space. Otherwise, factor in the cost to update the new area to match the existing landscaping with bushes, trees, or other features. Landscaping a new area could cost between $500 and $2,500.

Home Addition Cost: Types of Home Additions

Choosing to add on to a house doesn’t have to be limited to a garage or bathroom. If your budget allows, you could expand the home’s footprint with functional and emotionally satisfying spaces ranging from bedrooms to sunrooms to family rooms. These less common options are completely doable and often solve the problem some homeowners have when they cannot find a new, larger house in their desired neighborhood. If you have the space, talk with a contractor about the associated costs of adding on any of the following types of additions.

Room Addition

Most homeowners are looking to add an extra one or two rooms to their house. This can be done on the ground level or the second floor. Room addition costs mainly depend on the kind of room being installed.

• Bedroom: A 10-foot by 12-foot bedroom costs $9,600 to $24,000 to build or an average of $80 to $200 per square foot. It costs less than a room that requires plumbing, but you’ll still need to add HVAC ductwork and finish work.
• Bathroom: Bathrooms can quickly surpass a budget if you have visions of a spacious, spa-like interior. High-end fixtures are the fastest way to increase the cost of a bathroom. You’ll pay between $20,000 and $90,000 to build a new bathroom, but consult with a contractor to determine how much does it cost to add a bathroom for your specific space.
• Sunroom: In sunny regions, adding a sunroom is a popular option that adds style and helps blend indoors and outdoors. You could build an all-glass or partial-glass sunroom, so the costs range from $25,000 to $80,000. Sunrooms typically don’t include any heating, so you’ll save on HVAC costs. Alternatively, you could purchase a prefabricated sunroom for $11,000.
• Four-season room: If having a sunroom all year makes you excited, then plan to budget for a sunroom that includes heat during the colder months. This feature will push the price to the higher end of the $25,000 to $80,000 spectrum, with an average of $300 per square foot in some cases.
• Family room: Creating a larger space for friends and family to gather is increasingly popular. When an outdoor deck isn’t an option due to frequent bad weather, opt to build a new or expanded family room. An 18-foot by 12-foot expansion will cost $17,300 to $43,200, with the higher end including custom built-in cabinets or high-end flooring.
• Kitchen: If your kitchen is too cramped, then adding more space can be helpful. Due to the complexity of the plumbing and electrical requirements, kitchen additions are more costly: $48,000 to $95,000 for 200 square feet.
• Laundry room: Design inspirations have made adding a laundry room a top option for home additions in recent years. You could add a new, stylish, functional laundry room for $5,000 to $7,000 for a space that helps you enjoy this chore.
• Home theater: For cinephiles, adding a home theater might top the wish list. This type of room typically goes in a basement, but extra soundproofing measures will be taken for an additional cost if it needs to be added on the ground level. Obtain a quote to know where your project would fall within the $20,000 to $70,000 range.

Adding a Second Story

When a homeowner decides to add a second story, it’s usually to add more than a single room—adding just a single room on top of a house would look odd. Adding a second story costs $100 to $300 per square foot but could run up to $500 for complex jobs that require more shoring up of the original house. It’s common for second-floor additions to cost $150,000 to $200,000 for an additional 1,000 square feet of space.

Home Extension Costs

In some cases, you may only need to do a home extension to get the extra space you need. These jobs range from garages and balconies to in-law suites and mudrooms.

• Garage: If it’s time to protect your cars or add more storage for outdoor equipment, you can expect to pay $23,900 or $49 per square foot for a 2-car garage. An enclosed garage will significantly increase your home value. Adding a detached garage without heating or air costs around $9,000 to $12,000.
• In-law suite: An in-law suite could range from a simple bedroom to a fully functioning studio apartment–style suite, depending on local building codes. The simple bedroom option costs $44,000, but a detached, fully independent, plumbed suite costs at least $100,000.
• Front porch: Porch options run from simple step expansions to full wrap-around verandas. Once you decide on the purpose of the porch, whether it’s functional or for entertainment, you can estimate the costs between $12,000 and $30,000.
• Modular addition: If you own a modular home, be aware that adding on is not always possible if the foundation can’t support it. But it’s possible to have a room addition prefabricated and added for a cost of $20,000 to $30,000. Speak with a contractor to learn which option is feasible for you.
• Bump-out: A bump-out is a small extension of an existing room. The cost depends on the house’s existing structure and materials, but the average cost is $4,000 to $9,000.
• Mudroom: A coat closet at the front door doesn’t seem to do the trick for larger families, so you might want to add a mudroom extension. For 36 extra square feet, you could pay $3,600 to $7,200 for a small room with closets, a door, and easy-to-clean flooring.
• Cantilever: If you’re adding a second floor to your house and want a larger footprint, you may need to cantilever the upper floor. This extends the upper footprint beyond the lower footprint by adding proper joists or even shoring it up with beams on the exterior. A cantilever addition costs $15,000 to $25,000 on average.
• Balcony: If space on the ground is at a premium—or you just want your own private outdoor space—a balcony is a fast way to gain an outdoor living area. A contractor can securely build a balcony suspended off an upper floor for $4,000 to $9,000.

Attic Conversion

Converting an open attic to a usable living area costs about as much as adding a new room, mostly to make sure there’s proper insulation, ventilation, light, and egress options. You can expect to pay between $40,000 and $50,000 for attic addition or conversion—they’re basically the same thing.

Benefits of a Home Addition

It’s a toss-up to decide where to spend your hard-earned money sometimes. If buying a new house isn’t an option, but you need extra space, then doing a home addition is a great solution. Home addition costs are well spent when improving and expanding a home. Here are several popular reasons to add to your home that will get you excited for this project.

More Space

This is likely the number one reason homeowners spend money on home additions. More space is a considerable benefit for growing families, holding large gatherings, or adding storage or living space. Adding only a few feet of space to a cramped bedroom can help couples regain their own space. Expanded living rooms offer more room for families and friends to gather for important events. More space allows for you to adhere to your lifestyle values.

Added Property Value

Many household construction projects increase your property value—the question is by how much. No project offers a dollar-for-dollar return, which is why it’s wise to avoid extravagant upgrades that won’t make a significant difference. However, some projects can boost your property value. A master suite addition returns 63 percent, a bathroom returns 53 percent, and a second-floor addition returns 65 percent. You could speak with a real estate agent or home appraiser to get an idea about which additions and features will best help your property value.

Added Luxury

If your bathroom is as small and basic as it gets, bumping out your bathroom could be a huge benefit that adds spacious luxury to an intimate area. Having a little extra room to take care of your personal needs is fast becoming necessary to appeal to future home buyers. Additionally, expanding a kitchen to add more appliances or counter space is another way to make a common living area appear more luxurious.

More Storage

Building a garage offers two immediate benefits: protection for your vehicles and extra storage space. If you already have a garage but still need extra storage space, bumping out a larger area for a laundry room and mudroom could be a perfect idea. With built-in cabinets and closets, you’ll have plenty of space to store outdoor items or seasonal clothing and bedding.

Moving Alternative

Almost every homeowner dreads the moving process simply because of the tremendous hassle of packing, moving, and then unpacking your life’s possessions. There’s also the possibility that you cannot find a house that suits your needs in the area you specifically want to raise your family. Choosing to build an addition on your home solves all of those problems—if you have space—and it’s usually cheaper than buying a new house.

Home Addition Cost: DIY vs. Hiring a Professional

Home additions aren’t much easier than building a home in the sense that each part of the complex construction process is involved—just on a smaller scale. Since home addition costs can quickly become overwhelming, it can be tempting to wonder if you can do at least some of the work on your own. You could safely tackle some DIY tasks, such as removing existing landscaping to prepare the site, doing some demolition on non-structural features, painting the finished room, or installing new landscaping. However, unless you’re skilled at other tasks like plumbing, framing, roofing, or installing drywall, a general contractor should handle the project.

Home construction projects involve many moving parts to get the job done right and on time. From obtaining permits to scheduling contractors to ensuring materials are up to spec, the money spent on a contractor is worth it. Reputable contractors are licensed and insured to ensure you’re not liable for any accidents that could occur, saving you the potential embarrassment of calling your homeowners insurance company to explain an error you made that will now cost more to repair. You’ll also appreciate that general contractors can obtain some materials and fixtures that aren’t available to the public, so be sure to ask them about any items they may already have on hand or what they could recommend for your project. They’ll help guide your planning and building decisions as you begin this exciting process.

How to Save Money on Home Addition Cost

Home addition costs quickly jump from affordable to expensive. Since spending more money on a home addition doesn’t guarantee an equal return on your investment, you’ll want to make sure you spend only what needs to be spent. Once you’ve got an idea of your budget and what kind of addition you need, use these suggestions to save money on your home addition cost.

• Get several bids. It only takes a little more time to get bids from several contractors. This helps you find the one who can create your vision at the price you can afford.
• Keep it simple but stylish. The fastest way to blow your budget is to choose expensive materials when other options work just as well. Choose what suits your style and your budget.
• Be flexible when needed. Sometimes you may need to pivot on a choice reasonably quickly for many reasons, like a sudden supplier problem. Or you may realize the double French doors are a luxury that just doesn’t suit your budget when a single door will work just fine.
• Use discount warehouses or repurposed materials. If you’re a fan of shabby chic or vintage fixtures and furnishings, then thrift your way out of expensive costs by finding deals at unexpected places like Habitat for Humanity or other thrift stores.
• Carefully consider DIY options. If you’ve never hung drywall, then let the pros handle that job. But if you know your way around a paint store, then be sure to negotiate the paint job out of the bid to save on labor. Also, consider doing your own demolition of old cabinets, nonstructural walls, and landscaping. Remember, you’ll need to haul it away at a cost, though.
• Make your decisions early and stick to them. Another fast way to rack up extra costs is to constantly change your mind or delay making decisions. A contractor juggles many tasks to make sure the project runs smoothly, so requesting change orders can become costly—as does choosing a different kind of flooring after the first kind was ordered.
• Check for tax credits or refunds. Many programs are available for homeowners to save money by installing energy-efficient appliances or solar or renewable energy resources.
• Consider building up rather than out. Have a contractor review your house to determine whether your floor plan will save you money with a build-up rather than a build-out.
• Look at prefabricated stand-alone options. Sometimes the extra space you need can function as its own building. Ask a contractor about prefabricated modular buildings that can work as an office or studio detached from the house, which reduces the building cost.

Questions to Ask About Home Addition Cost

It’s easy to get overwhelmed by the process of planning and executing a home addition. You’ll need to find a contractor you trust, who is reliable, and who will achieve your vision with ease. Use any of the following questions when talking to a licensed, insured, and bonded general contractor to help make the process easier and avoid miscommunication.

• How long have you been in business?
• Can I see a portfolio of your work?
• How do you calculate home addition costs?
• Can I review a line item bid?
• Will you provide a fixed-price contract with a detailed scope of work?
• Will you pay the subcontractors?
• What kind of payment schedule do you prefer?
• What do you suggest as the top ways to save money on this project?
• Do you already have some extra materials (like flooring) available that I could purchase at a discount?
• After looking at my house and my ideas, do you have suggestions for materials or designs that may work better?
• How can we make sure the addition looks like it’s intentionally part of the house rather than sticking out like a sore thumb?
• Do I need to hire an architect?
• Will my second-floor addition require us to strengthen the existing foundation? If so, what will that cost?
• Will you obtain the necessary permits?
• Are there any zoning restrictions to consider?
• Will you or a manager be on-site when the subcontractors are here in case of problems or questions?
• What if I decide to make a big change partway through the project?
• What hours will the workers be here?
• Will you have other major projects you’re working on at the same time, or will mine be a priority?
• What is the anticipated timeline to complete my home addition?
• How much value will this addition add to my house?
• What kind of warranties and guarantees do you offer?

FAQs

The options are nearly endless when building a home addition, but choosing a general contractor and laying out a specific plan for your project will get you started on the right foot. As you begin finalizing your decisions, consider these answers to some frequently asked questions.

Q. How much does a mobile home addition cost?

It’s entirely dependent on the kind of addition. A metal carport costs $2,300 to $4,850, but a porch could cost $4,600 to $22,000. These additions will not be structurally attached to a mobile home to avoid straining the structure.

Q. Does a Cape Cod addition cost more than other home styles?

It might. Cape Cod additions are a unique and stylish way to add space to your house, and with that style often comes extra costs. Speak with a local contractor near you to find out the most cost-effective way to build this style of home addition.

Q. Do I need to hire an architect for additions?

An architect is a must if you’re looking at an extensive addition that alters walls, redesigns room flow, or affects any other major structural changes to the roof or foundation. An architect’s expertise will ensure the addition is structurally sound and meets building code requirements. Suppose you’re doing a simpler addition like a bump-out or single room addition. In that case, you may not need an architect if the general contractor is experienced at updating blueprints and meeting zoning codes.

Sources: HomeAdvisor, Fixr, Thumbtack, HomeGuide