How Much Does a Home Addition Cost?
If you feel like you do not have enough space in your current home but love everything else about it, adding an addition makes your property exactly what you want. Additions come in many shapes and sizes, from tiny bump-outs to full second stories.
For this reason, there is a large range of costs associated with building an addition. The national range is $20,000 - $100,000 with most people spending around $55,000 on a 240 sq.ft. addition on the first floor. The low cost for this project is $7,000 for a first-floor laundry room bump out, while the high cost is $200,000 for a 1,000 sq.ft. second-floor addition with a new roof.
Home Addition Costs
| Cost to Add a Room | |
|---|---|
| National Average Cost | $55,000 |
| Average Range | $20,000-$100,000 |
| Minimum Cost | $7,000 |
| Maximum Cost | $200,000 |
In this guide
Room Addition Costs by Size
Home Extension Cost by Type of Room
Home Extension Cost by Type
Cost to Add a Second Story
Cost of Adding a Basement to an Existing Home
Cost to Design a Home Addition
Home Addition Cost Breakdown
Labor Costs to Build an Addition
Factors that Affect the Cost of Expanding Your House
Cost to Draft a Home Addition
Cost of Framing an Addition
Enhancement and Improvement Costs
Additional Considerations
FAQs
References
Updated:
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New Space Addition Cost by Project Range
Home Addition Cost per Square Foot
There is a range of associated costs per square foot 1 for a home addition, depending on the room’s use, how much existing space is used, and where the addition is built. In general, expect to pay roughly $200 a square foot for a finished addition. Some complex projects may cost more, while very simple ones may cost less. Based on this figure, the following spaces have these costs:
| Size | Average Cost |
|---|---|
| 200 sq.ft. | $40,000 |
| 300 sq.ft. | $60,000 |
| 400 sq.ft. | $80,000 |
| 500 sq.ft. | $100,000 |
| 600 sq.ft. | $120,000 |
| 800 sq.ft. | $160,000 |
| 1,000 sq.ft. | $200,000 |
200 Sq.Ft. Addition Cost
The average cost of a 200 sq.ft. addition is around $40,000. An addition of this size is large enough to house a kitchen, master bedroom, or larger living or family room. Your exact costs for this addition can change depending on what you do with the space, with kitchens costing more than living rooms. The more elaborate the addition, the higher the total costs. Things like crown molding and heavier window and door trim can contribute to higher total costs.
300 Sq.Ft. Addition Cost
The average cost of a 300 sq.ft. addition is approximately $60,000. Additions of this size are large enough for a kitchen with an eat-in breakfast nook or a large family room. You could also use an addition of this size for a combination of mudroom and laundry room. Keep in mind that as with any size addition, what you do with the space ultimately dictates your final price. Additions with plumbing fixtures cost more than those without, and additions with a lot of decorative detail also cost more.
Cost to Add 400 Square Feet to a House
The cost for a 400 sq.ft. addition averages $80,000. Additions of this size are large enough for multi-use spaces. This could mean a kitchen and dining room or a master bedroom with an attached bathroom. At this size, you may also be considering a two-story addition, with 200 sq.ft. on each floor. All these variables can mean a slightly wider fluctuation in final costs. If you add plumbing for a kitchen or bathroom or it is a two-story addition, your costs can be higher.
Cost to Add 500 Square Feet to a House
The average cost of a 500 sq.ft. addition is around $100,000. An addition of this size offers many possibilities. You can add a single large space for expanding open floor plans. You can also add multifunctional rooms. This could be a large kitchen with a breakfast bar and dining room. Or it could be two bedrooms with a Jack-and-Jill bathroom between them. As with other additions, things like plumbing can mean a higher final cost.
600 Sq.Ft. Addition Cost
The cost of a 600 sq.ft. addition averages $120,000. 600 sq.ft. is large enough to offer numerous possibilities. At this size, you can add a full-sized master suite to the home. This could contain not only a master bedroom and bathroom but also walk-in closets, changing areas, and conversation areas. An addition of this size can also add a family room with a home office or two large bedrooms with a Jack-and-Jill bath between them. You could also choose to add a 2-story addition at this size, although this can raise costs.
Cost to Add an 800 Square Foot Addition
The average cost of an 800 sq.ft. addition is about $160,000. An addition of this size is large enough to create many possibilities as well. This size addition could be a partial second floor addition. This could mean adding a second floor above a large garage, with a connecting hallway to the main home, for example. You could also create a two-story addition with one large room on each level. As with any addition, adding plumbing or roofing to the equation, can raise your final costs.
1,000 Sq.Ft. Addition Cost
A 1,000 sq.ft. addition costs around $200,000 to complete. This is a sizable addition to any home. In some cases, it can double the square footage of a smaller home. Additions of this size are usually full or partial second-story modifications. They can also be a garage addition with a finished living space above it. With an addition this large, ensure you have the space and zoning in order to complete the project.
Room Addition Costs by Size
The size of the room you add has an impact on its total cost, with larger spaces costing more than smaller ones. Keep in mind different types of rooms have varying costs regardless of size. The following room sizes have these costs on average:
| Room Size | Average Cost |
|---|---|
| 6’ x 8’ | $9,600 |
| 8’ x 10’ | $16,000 |
| 8’ x 12’ | $19,200 |
| 10’ x 10’ | $20,000 |
| 10’ x 12’ | $24,000 |
| 10’ x 15’ | $30,000 |
| 10’ x 20’ | $40,000 |
| 12’ x 12’ | $28,800 |
| 12’ x 16’ | $38,400 |
| 15’ x 20’ | $60,000 |
| 16’ x 16’ | $51,200 |
| 20’ x 20’ | $80,000 |
| 20’ x 40’ | $160,000 |
Home Extension Cost by Type of Room
The room type you add impacts the total project cost as well. Closets, cabinets, plumbing, flooring, and other details make the space more or less expensive than the average cost. Below are some of the average prices for building different rooms based on the most common sizes for each space.
| Type of Room | Average Cost |
|---|---|
| Laundry Room | $5,000 - $8,000 |
| Mudroom | $10,000 - $14,000 |
| Bathroom | $20,000 - $60,000 |
| Home Theater | $20,000 - $70,000 |
| Sunroom | $35,000 - $55,000 |
| Bedroom | $37,000 - $100,000 |
| Attic | $40,000 - $50,000 |
| Family Room | $40,000 - $60,000 |
| Living Room | $40,000 - $60,000 |
| Kitchen | $50,000 - $70,000 |
Laundry Room Addition Cost
Laundry rooms cost between $5,000 and $8,000 on average for an addition. The average laundry room is only around 35 square feet, making this more of a bump out than a full addition. Laundry rooms need to be waterproof and usually include cabinetry or storage along with the appliances.
Mudroom Addition Cost
Mudroom additions range from $10,000 to $14,000. A mudroom addition is usually around 50 square feet, so even with the included cubbies and organizational material needed, it costs around $12,000. The average mudroom includes cabinets, storage, and a durable flooring, such as porcelain or slate 2, in the price.
Bathroom Addition Cost
A full bathroom addition of 48 square feet in a new space costs between $20,000 and $60,000. While this is a small space, it has extra needs for plumbing, raising the costs. Bathroom additions include everything from the shower to the sink and toilet, along with tile and accessories.
Home Theater Addition Cost
Home theater additions can range in cost from $20,000 to $70,000. Adding a home theater brings fun and entertainment to your home. They may be added to basements or existing spaces or built onto your home if you do not have the space. Because of the need for acoustic materials and equipment costs, they can have a wide range of costs.
Sunroom Addition Cost
Sunroom additions range in cost from $35,000 to $55,000. The sunroom takes on several different forms and building styles. Sunrooms have windows or screens or full walls, depending on your goals. They cost an average of $45,000 for a three-season room.
Bedroom Addition Cost
Bedroom additions have a wide range of costs from $37,000 to $100,000 on average. Bedroom additions may be slightly smaller, but they have additional needs for closets, which raise the cost slightly. Closets, storage, and the necessary lighting drive up the costs closer to an average of $57,000, despite the smaller size.
Attic Addition Cost
Attic additions typically cost between $40,000 and $50,000. While it is called an attic addition, this is an attic conversion. It is still a relatively large project. This includes making sure there is an egress like stairs and working with the lower ceilings, so you may have less space than you imagine with this type of addition.
Family Room Addition Cost
Family room additions average $40,000 to $60,000. The family room comes in many shapes and sizes and is finished in numerous ways. Family rooms are usually informal and made for the family, so they include storage, entertainment areas, and space to spread out.
Living Room Addition Cost
Living room additions cost between $40,000 and $60,000 on average. The living room is often smaller but more formal than the family room. So while there is less space, it is more likely to have higher-end materials like exotic hardwood or marble floors and nicer features and moldings.
Kitchen Addition Cost
Most kitchen additions range from $50,000 to $70,000. Kitchen additions often have added costs for cabinetry and plumbing, so while the average size of the kitchen falls between 100 and 200 square feet, the cost averages around $60,000. The average kitchen addition includes flooring, cabinets, counters, appliances, and framing and finishing, driving most of the total cost.
Home Extension Cost by Type
There are many other ways to add to your home to expand your living space, and not all create complete rooms. Extensions can be a way for you to gain valuable square footage and living space, without all the expense of a full addition. You can create an extension in many ways, from simple bump outs, balconies, and dormers to in-law apartments. An extension can come in a wide range of sizes and costs and have a variety of appearances.
| Extension Type | Average Cost |
|---|---|
| Bump Out | $4,000 - $9,000 |
| Dormer | $4,000 - $9,000 |
| Balcony | $4,000 - $9,000 |
| Greenhouse | $5,000 - $20,000 |
| Porch | $12,000 - $30,000 |
| Cantilever | $15,000 - $25,000 |
| Modular | $20,000 - $30,000 |
| Garage | $22,000 - $43,000 |
| In-law | $60,000 - $100,000 |
Bump Out Addition Cost
Bump out additions typically cost between $4,000 and $9,000. A bump out is a small extension of an existing room. It adds square footage but at a much lower cost. Because this is not a full room, the costs are considerably lower. Bump outs are most common on the first floor, but they can be done on the second floor as well. They are good for adding small spaces like laundry rooms and adding storage to a room.
Dormer Addition Cost
Dormer additions range from $4,000 to $9,000 on average. A dormer is a roof extension with a window. It adds extra space to a low-ceilinged room like an attic space. On the inside, the dormer can create a window seat with added storage. If your ceilings are high enough, it can also create additional standing room. Dormers are also attractive additions on the exterior since it changes the profile of your home and can make it look more attractive.
Balcony Addition Cost
Balcony additions average $4,000 to $9,000. A balcony is a small deck suspended off the side of the home and is usually a short and simple project. It is a nice way of updating your home’s exterior, while gaining usable outdoor space. If you do not have the room for a full deck or porch but want somewhere to sit outdoors, a balcony makes a lot of sense. They can come in many sizes and styles to complement all homes.
Greenhouse Addition Cost
Greenhouses typically cost between $5,000 and $20,000 on average. If you do a lot of gardening, add a greenhouse to your property. There are several different ways you can do this. You can add the greenhouse directly onto your existing home, creating a lean-to style structure. You can also make the greenhouse a completely separate structure of many different shapes and sizes elsewhere on your property. Each style has its own costs as well as pros and cons to consider.
Porch Addition Cost
Porch additions range from $12,000 to $30,000. Adding a porch boosts your home’s curb appeal and value while adding outdoor living space. Porches come in a wide range of sizes and styles. They can be small porticos at your entrance or enormous verandahs that wrap around the house. A porch can give you a lot of space for recreation and entertaining, while at the same time improving the appearance of your home.
Cantilever Addition Cost
Cantilevering an addition onto your home averages $15,000 to $25,000. If you want to add a room to the second floor of a home, extend the space by cantilevering it out over the lower floor. These spaces are not big, but the added support increases costs. The space below can be supported on posts, similar to a deck, or it can be supported by having the posts angle back to the house. They brace themselves against the house itself, so no actual ground space is taken.
Modular Room Addition Cost
Modular room additions cost between $20,000 and $30,000 on average. Modular building is less expensive than traditional because the room is factory-built, delivered, and added onto your existing home. The cost per square foot is lower, and the timeline is faster. Best of all, modular additions can be made in nearly any style, size, or configuration. So you can easily get one that seamlessly matches up with the rest of your home.
Garage Addition Cost
The cost of a garage addition ranges from $22,000 to $43,000 on average. Having an attached garage improves your home’s value and improves overall function as well. With an attached garage, your car is more secure and protected from the elements. Garages also offer a lot of storage and can also be used for a variety of other purposes. You can use your garage as a workshop, gym, or any number of other uses.
In-Law Addition Cost
An in-law addition has a cost range of $60,000 to $100,000, depending on the size. An in-law is a fully fitted small building or apartment that is either attached or detached from the rest of your home. Because they often contain kitchens and baths, their costs are higher than additions of a similar size without these features. In-laws can be a great way to have multi-generational families living together under one roof. They require a separate entrance from the main home, as well as other features that make them a stand-alone apartment.
Cost to Add a Second Story
Second story additions have much higher costs than adding a room on the ground level 3 of your home. They involve removing your roof and attic, adding a new floor, walls, and roof for several rooms. This often makes the cost per square foot between $300 and $500, and it is common for the total addition cost to reach $150,000 to $200,000 for homes that are 1,000 sq.ft. or larger. For smaller homes, it costs $90,000 to $120,000.
Cost of Adding a Basement to an Existing Home
To add a basement to an existing home, you must give it a new foundation, which means lifting your home, excavating the area, and pouring a new foundation. This has a range of costs, depending on how high the house needs to be lifted and how big the basement is. Expect costs to be at least $50,000 for this project. They may be much higher, depending on factors like your location, soil, and house size.
Cost to Design a Home Addition
Do not overlook the designing aspect of the addition because it is an important step. Your addition must match the details of your home inside and out to be seamless and to get the most value. Designing also makes the most of the space, so more is done with less square footage.
The general rule of thumb when it comes to the cost of designing a home addition is for the designs to cost between 10% and 17% of the final costs. So, for a 240 sq.ft addition costing $55,000, you pay between& $5,500 and $9,350. This varies, depending on the designer and detail of the plans.
Home Addition Cost Breakdown
While every project is different, most have several factors in common that give an idea of where your costs are going during an addition. Additions need specific materials both inside and out that match with the rest of your home. In addition to the materials, the professionals you contact with will not vary much from project to project. The following cost breakdown can give you a good idea of what the various parts of your project will cost.
| Factor | Average Cost Range |
|---|---|
| Insulation | $0.12 - $6.87/sq.ft. |
| Drywall | $1 - $3/sq.ft. |
| Roofing | $2 - $3/sq.ft. |
| Painting and Finishing | $2 - $5/sq.ft. |
| Electrical | $3 - $5/linear foot |
| Siding | $3 - $12/sq.ft. |
| Flooring | $3 - $20/sq.ft. |
| Trusses (roof framing) | $4 - $8 per board foot |
| Framing | $9 - $18/sq.ft. |
| HVAC | $35 - $55/linear foot |
| Doors | $350 - $1,100 each |
| Windows | $650 - $1,500 each |
| Design Costs | $2,000 - $20,000 |
Keep in mind that this is a general range that nearly all additions include. Specialty rooms like kitchens have additional costs.
Labor Costs to Build an Addition
The labor portion of your project is dictated largely by which professionals you use and in what capacities. In many cases, you hire a builder or general contractor, and they subcontract out the various specialties, so you are not paying each pro directly. Expect to pay the following rates:
Architect - $150 - $400/hour
Electrician - $65 - $85/hour
Roofer - $2 - $3/sq.ft.
Siding Contractor - $40 - $50/hour
Carpenter - $70/hour
HVAC technician - $50 - $100/hour
Framing professionals - $4 - $10/sq.ft.
Painters - $50/hour
Flooring installers - $1 - $5/sq.ft.
Drywall installers - $1 - $3/sq.ft.
General contractor - $150/hour
You may also need a plumber at $45 - $200/hour if your addition is a kitchen or bathroom.
Factors that Affect the Cost of Expanding Your House
Every project is different, and many factors impact the cost of your addition. These include the materials used, finishing choices, labor costs in your area, addition size and placement, how you heat and cool the addition, amount of design, and prep work entailed. Any special extras like built-in 4 cabinets or shelves all impact the final addition cost.
Cost to Draft a Home Addition
Most home additions need a set of blueprints, just like any other major build. A draftsperson works with an architect or builder to produce these. These blueprints are incredibly important to all projects. They are necessary to pull permits in many cases and help you better visualize your finished project. These blueprints include all the necessary details for the job, including light plans, plumbing layouts, and material choices. They have an average cost of around $1,200.
Cost of Framing an Addition
Your addition is framed in the same manner and materials as the rest of your home. This provides structure for the space and is integral to the project. The frame is one of the first parts of the addition, along with the foundation in some cases. Everything else from the drywall to siding needs that frame in order to have structure. The frame can be made of wood or metal and usually matches the framing material for the rest of the home. Framing has an average cost of around $2,500 for a new addition.
Enhancement and Improvement Costs
HVAC
In some cases, you may extend things like ducts into your new addition, but in other cases, this stresses your current system too much. It may be a better choice to heat and cool your addition separately. Things like ductless heat pumps are good for additions because they do not tie into your existing system. The cost for a single-zone system is just over $2,000.
Post-Construction Cleaning
Additions are very messy both in the new area and in your existing space. Post-construction cleaning makes your space livable faster. This has an average cost of around $550.
Interior Designer
An interior designer is often helpful when adding a new space because they help you see the possibilities and help furnish it. The average cost of hiring an interior designer for one room in the home is around $5,500.
Additional Considerations and Costs
- Additions add value to your home, but keep in mind that this value is likely not equal to the cost. Additions add the most value when they keep the design of the rest of the home.
- Make sure you get your contract in writing, including the total amount and the breakdown of materials and details. Include a lien release in the contract for protection.
- Sometimes, remodeling instead of adding on gains space. For example, you may remodel a basement to gain extra space often for less.
- Mobile homes also have additions, but these must be considered separate structures from the rest of the building and have its own foundation. This costs around $150 - $300 a square foot.
- Have your contractor obtain the permits needed for the addition. They often know tricks that help speed the process.
- Make sure the area you are building onto is accessible both inside and out. This means removing landscaping and moving furniture and window coverings in most cases.
- You may do your own demolition, tearing down the walls and hauling away the debris, to save money.
- The average timeline to build a new home addition is between 2 and 3 months from start to finish.
- Before ordering new material, check with your contractor to see if they have any leftover material used. This may save you money. Using stock sizes instead of custom also helps reduce costs.
- You will likely need to compromise on this project in some way, whether on the size, materials, or timeline to meet your budget. It is fine to start with your ideal project, but then try to cut back.
- Keep resale in mind when you add to your home. Make sure the addition fits the rest of your home and neighborhood to ensure it appeals to buyers.
FAQs
- How much does a 2-story addition cost?
Expect costs for a 2-story addition to be around $300 - $500 a square foot, while single-story additions are closer to $200 a square foot. Both vary in costs depending on many factors.
- How much does it cost to add another bedroom to your house?
The average cost to add a bedroom addition is around $57,000.
- Are architects or draftsmen needed for additions?
You do not necessarily need an architect or draftsman. Use a design/build firm to handle the initial drawings or start with a designer or architect. It is a good idea to have blueprints 5 made.
- How much does an addition cost on a ranch house?
This depends on the addition’s size, with most costing roughly $200 a square foot.
- How much should I budget for a home addition?
This depends on the size and type of the addition. In most cases, $200 a square foot is a good estimate.
- How much does a 20’ x 20’ addition cost?
An addition of this size is 400 sq.ft., which translates to an average cost of around $80,000 for the project.
- How much does it cost to add a 12’ x 12’ room?
The average cost to add a room of this size is around $28,800. A room this size can be used as a small bedroom or living room, so costs are not as high as some larger spaces.
References
- Craftsman Book Company. National Construction Estimator, 69th ed., Ed. by Richard Pray (Carlsbad, CA, 2021).
- Craftsman Book Company. National Home Improvement Estimator, Ed. by Ray F. Hicks (Carlsbad, CA, 2021).
- Family Handyman. “14 Ways to Add Space to Your Home that Won’t Break the Bank."
https://www.familyhandyman.com/list/14-ways-to-add-space-to-your-home-that-wont-break-the-bank/ - FIXR Cost Guides and Cost Database.
- Old House Online. “5 Ideas for Adding On.”
https://www.oldhouseonline.com/repairs-and-how-to/5-ideas-for-adding-on/ - Rocket Mortgage. “Adding An Addition Onto Your House: What You Need To Know."
https://www.rocketmortgage.com/learn/adding-an-addition-onto-your-house - The Nest. “What Is Cheaper — Adding a Second Story Addition or a Ground Floor Addition?"
https://budgeting.thenest.com/cheaper-adding-second-story-addition-ground-floor-addition-22059.html - The Spruce. “4 Types of House Additions to Add More Space."
https://www.thespruce.com/types-of-house-additions-1821124 - The Spruce. “Building a House Addition: Pros and Cons."
https://www.thespruce.com/house-addition-deliberation-1821280 - This Old House. “Read This Before You Hire an Architect."
https://www.thisoldhouse.com/21015821/read-this-before-you-hire-an-architect - Trillium Architects. “Estimating Home-Construction Costs."
https://www.trilliumarchitects.com/ii-construction-costs - Wise Bread. “Architect, Designer, or Contractor: Who Should You Hire for Your Project?”
https://www.wisebread.com/architect-designer-or-contractor-who-should-you-hire-for-your-project
Remodeling Terms Cheat Sheet
Definitions in laymen's terms, cost considerations, pictures and things you need to know.See full cheat sheet.
1 Foot: A support for the foundation of a house that also helps prevent settling. It is typically made of concrete reinforced with rebar, but can also be made of masonry or brick. It is usually built under a heavier part of the house like a wall or column, to distribute the weight of the house over a larger area.
2 Slate: A fine-grained rock, typically bluish-gray in color, that can easily be split into thin layers and is commonly used as a roofing material
4 Built-in: An item of furniture, such as a bookcase or set of cabinets, that is built directly into the structure of the room. Built-ins are therefore customized to the room and not detachable
5 Blueprints: A technical drawing of an architectural design. Traditionally these were made using a printing process that produced a white line on a blue background. They can also be made with CAD software and a large-scale printer
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