How Much Does a Home Addition Cost?

Adding space to your home can be one of the best investments you make. Whether you need a larger kitchen, extra bedrooms for a growing family, or want to build the luxurious master suite you’ve always dreamed of, a home addition allows you to expand and customize your living space to perfectly suit your needs.

But before you start drawing up plans, the big question is – how much will it cost? Home additions can range from simple projects like adding a family room over your garage to complex renovations like digging out a basement. Costs vary widely based on the size and scope of work.

Understanding the key factors that influence addition costs will help you budget for your project and set realistic expectations. In this comprehensive guide, we’ll walk through everything you need to know about home addition costs, including:

Average Cost of Home Additions

On average, a home addition costs $167,331 to build. According to the 2021 Cost vs Value report by Remodeling Magazine, this breaks down to around $269 per square foot.

To give you a better idea of real-world addition costs, here are the average prices reported for common addition projects:

  • Master suite addition – $142,744
  • Family room addition – $97,793
  • Bedroom addition – $108,432
  • Bathroom addition – $51,627
  • Sunroom addition – $79,754

Keep in mind, these are just baseline numbers. The specifics of your project, like the size and layout, luxury finishes and modifications to existing structure, will all cause your final price to deviate from the average.

Key Factors That Influence Cost

Many elements contribute to your total addition cost. The major factors include:


The amount of square footage you’re adding is the primary cost driver. The larger the footprint, the more material and labor will be required. According to the estimates above, you can expect to pay around $250-300 per square foot for a home addition.

Scope of Work

What’s involved in your project will have a significant impact on pricing. A simple bump-out addition will cost much less than adding a second story or basement renovation requiring excavation. Complex projects with structural changes, HVAC, and electrical upgrades will increase costs.


Using higher end finishes like granite countertops, hardwood floors and tile upgrades will add to your bottom line. Luxury materials, specialty items like glass block and pricier brands can raise costs exponentially.


Like real estate, location matters for addition costs too. Projects in high cost-of-living urban areas or using specialized contractors for remote rural locations may have a higher price tag. Permit and utility fees also vary by region.

Existing Home Layout

How the addition connects to your current footprint impacts accessibility and complexity. Adding onto an existing kitchen or den is simpler than building an entirely new wing requiring utility connections.


Adding onto an existing foundation is cheaper than pouring a new one. A freestanding structure like a garage will require extra foundation costs to be factored in.

Access Issues

Limited space to maneuver equipment and supplies during construction will drive up pricing for additions in urban settings or on small lots. Tricky access issues due to slopes and trees also increase costs.

Factors That Reduce Cost

While the upgrades and complexities associated with your specific addition will increase costs, you may also benefit from some cost-saving factors, including:

  • Economies of scale – Simultaneously remodelling other parts of your home allows contractors to offer discounts compared to doing projects separately.
  • DIY contributions – You can save on labor costs by doing prep work or finishing stages yourself if you’re handy. However, this may require general contracting skills.
  • Prefab materials – Structural insulated panels (SIPs) and other prefabricated framing and sheathing materials can reduce material costs and speed up construction.
  • Smaller scope – Adding onto an existing room instead of building an entirely new addition saves on foundation and roofing costs.
  • New building codes – Energy efficient features like better insulation and windows in newer building codes lower utility costs over time.
  • Financing incentives – Some energy companies offer rebates and financing incentives for efficiency upgrades incorporated into home additions and renovations.

How Much Does Each Addition Type Cost?

Now let’s take a closer look at the typical price range for popular types of home additions:

Master Bedroom Suite Addition

Adding a spacious master suite with a bedroom, bathroom, and walk-in closet provides homeowners with a private oasis.

Cost: $125,000 to $250,000

A master suite addition costs $142,744 on average. The size of the addition and features included impact overall pricing. For example, a 400 square foot suite with midrange finishes would cost around $125,000. For a premium 600 square foot master suite with spa bath, upscale tile and finishes, the cost could reach $250,000.

Expanding an Existing Bedroom

For growing families needing more space, adding dormer space above an existing room or expanding the footprint provides added square footage.

Cost: $25,000 to $150,000

On the more affordable end, enclosing an attic over a bedroom for $25,000 to $50,000 can add usable space. To expand the size of a room outwards, plan on spending $100,000 to $150,000. The cost depends on how much space you’re gaining and whether structural changes are needed.

Building Out a Basement

Whether finishing an unfinished basement or digging out space under an existing home, basement additions deliver extra living area.

Cost: $50,000 to $100,000

For a basic basement buildout with drywall, paint, and carpeting in a 600 square foot space, budget $50,000 to $75,000. For an elaborate remodel with a bathroom, wet bar and media room, costs can double to the $100,000 range when including mechanicals and extensive remodeling.

Bump-Out Addition

Bump-out additions extend a portion of a room outward to gain more interior space. This scaled down addition is a budget-friendly way to add livable square footage.

Cost: $25,000 to $100,000

Enclosing a 12’ x 12’ section of a kitchen or living room with a bump-out costs between $25,000 and $50,000 on average. More elaborate bump-outs up to 250 square feet for a dining space or master bath addition may run $50,000 to $100,000.

Second Story Addition

Gaining bedroom, bathroom and living space by adding another level on top of the existing first floor is a significant but high-value project.

Cost: $150,000 to $300,000

For a simple 400 square foot addition, expect to pay around $150,000 to $200,000. Larger or more complex second story additions with high-end finishes could cost $200,000 to $300,000.

Attached Garage Addition

Attached garages provide convenient covered parking and overflow storage space.

Cost: $35,000 to $60,000

The cost for a 2-3 car garage addition averages $35,000 to $60,000. Single car garages start around $20,000. Garage cost depends mainly on the interior square footage.

Sunroom Addition

Bright, airy sunrooms increase natural light and integrate indoor and outdoor living spaces.

Cost: $25,000 to $150,000

Enclosing a patio or deck to create a basic 200 square foot sunroom costs around $25,000. For a high-end customized space with features like multiple french doors, cathedral ceilings and skylights, expect to spend $100,000 to $150,000.

In-Law Suite Addition

Sometimes called accessory dwelling units or “granny flats,” these independent living spaces accommodate relatives or guests.

Cost: $100,000 to $250,000

For a compact 400 square foot detached suite, plan on spending around $100,000. More like an apartment at 800+ square feet with a kitchen, bedroom and living room, in-law suites cost closer to $250,000.

What’s Included in Your Home Addition Cost?

When budgeting for your home addition, remember that the quoted cost for the built out square footage is just one line item. Here’s a breakdown of all the essential services and costs that will factor into your total project expenditures:

  • Permits – Building permits, tap fees, site surveys and approvals may cost $1,000 to $5,000+ depending on your municipality.
  • Architectural Design Fees – For an architect to draw up your plans, expect to pay 10-15% of the total project cost.
  • Foundation & Framing – Materials and labor for laying the foundation, framing walls, trusses, etc.
  • Roofing – Removing portions of existing roofing, adding new roof sections, flashings, etc.
  • Siding & Exterior – Matching or complementing new exterior finishes to the existing aesthetic.
  • Insulation – Adding proper insulation to new exterior walls, ceilings and foundation.
  • Drywall & Paint – Finishing interior walls and ceilings.
  • Flooring – New flooring installation and integrations with existing floors.
  • HVAC – Heating, cooling and ventilation systems additions and rerouting.
  • Plumbing – Extending water and sewer lines, adding fixtures like sinks and toilets.
  • Electric – Wiring for lighting, outlets, switches and circuits, may require panel upgrade.
  • Low-Voltage Systems – TV, internet and phone, speakers, smart home devices.
  • Bathroom & Kitchen Fixtures – Install of cabinets, countertops, vanities and appliances.
  • Trim Finishes – Installing baseboard, crown molding, door/window casings, etc.
  • Labor – All construction and skilled trades professional fees.
  • Overhead & Profit Margins – What the general contractor or company charges for their work and expertise. Industry standard is a 10-20% markup.

In summary, the complete costs of even a “basic” addition really add up! Being realistic about your budget and understanding what every dollar is buying will help you plan and prepare for a successful project.

Can I Do a Home Addition Myself?

Is DIY-ing part or all of your home addition something to consider to save money? That depends on your skill level and access to equipment.

Smaller projects like finishing a basement or building a sunroom addition over a deck are within reach for an ambitious and experienced DIYer. You can also save on labor costs by doing prep work like demolishing existing structures or assisting with finish trim and painting.

However, additions require expertise in structural engineering, electrical and HVAC systems, and finishing work. Make safety the number one priority – mistakes made during framing or roofing could have disastrous and expensive consequences later.

We recommend consulting with a general contractor and subcontractors to determine what portions of the work you can take on yourself without compromising quality or safety. Some great DIY addition projects include:

  • Demolition of old deck/patio
  • Exterior painting
  • Installation of floors
  • Trim carpentry and caulking
  • Landscaping after completion

Focus your DIY efforts on unskilled labor intensive tasks or non-structural finishes to get the most value from your time invested.

How Long Does It Take to Build an Addition?

Another consideration beyond the project cost is the time investment. Home additions take weeks to months to complete.

  • Planning & Permits – 4-12 weeks
  • Construction Drawings – 2-4 weeks
  • Construction – 8-24 weeks

Factors impacting the timeline include permitting and approvals, size and complexity of the addition, weather delays, and contractor availability. Talk to your contractor about ways to streamline the schedule when planning your project.

When Does a Remodel Become More Cost Effective?

Sometimes upgrading your current home just isn’t possible to achieve your dream layout. When you’ve fully maximized the potential of your existing footprint, an addition is the next step to truly customize your space.

As a rule of thumb, if your remodel requires structural changes like moving or removing walls and you’ll be gaining 50 square feet or more, an addition has the benefit of working with a blank slate layout.

The reconstruction required for a massive remodel can send costs spiralling. Starting fresh with an addition avoids some of the inefficiencies and demolition costs of working within your current walls.

Carefully weigh your goals – a lower cost remodel may simply spruce up your home, while an addition creates the fully customized space your family needs.

Adding Value With a Home Addition

One of the biggest appeal of additions is that they can quickly build equity by increasing a home’s value. According to the Remodeling magazine’s 2021 Cost vs. Value report, the average home addition recoups ~68% of costs at resale.

With strategic renovations like adding square footage, bathrooms and converting unfinished basements into living space, you can reap an even higher ROI of up to 75-85%.

The improvements also directly enhance your living experience. Additions create the opportunity to reimagine how your home functions and freely expand it to match your lifestyle.

Is an Addition or Move Better Financially?

Should you expand your current home or find another property that better suits your needs? It comes down to crunching the numbers.

Compare the investment of your planned addition to the costs of purchasing a larger home. Factor in the financial and emotional costs of moving as well.

Additions average around $100 to $300 per square foot. In many markets, you may pay more per square foot to purchase an equivalent sized home nearby. Combining that savings with your existing home’s equity can make staying put and building out more cost effective.

However, there are cases where moving makes more financial sense:

  • You’ve outgrown your neighborhood (like needing more land or better schools).
  • Zoning laws limit addition possibilities.
  • Structural constraints make additions impractical.
  • Your current home lacks basics you now need like a garage.

Create a budget for both scenarios – addition vs. new home purchase – to make the best money decision for your situation.

Finding the Right General Contractor

Selecting the GC or renovation firm to execute your project is critical. Ask prospective contractors about:

  • Past addition experience – How many similar projects have they completed successfully? Can they provide referrals?
  • Project timeframe – Do their estimated timelines align with your goals and expectations? Avoid contractors promising unrealistically fast construction.
  • Subcontractor relationships – Do they have trusted electricians, plumbers and other subs they partner with regularly? These relationships get things done faster.
  • Upfront pricing – Are they transparent about itemized costs and fees or do they dodge giving quotes? Fixed price contracts prevent budget surprises.
  • Communication style – Do they listen and address all your questions and concerns? Good communication alleviates headaches.

Take time to thoroughly vet GCs to find the right fit. An experienced contractor you connect well with is key to achieving the home addition you’ve always envisioned.


While expanding your living space is a major investment, smart planning lets you execute the addition you need within budget. Understanding the factors that make prices fluctuate helps you create accurate estimates. With realistic expectations set, you can confidently embark on an exciting home addition project that adds value for years to come.

How Much Does a Home Addition Cost? – Key FAQs

Home additions are a complex project with many variables that influence costs. Here are answers to some frequently asked questions about how much you can expect to budget for your home expansion.

How much does it cost per square foot to add on to a house?

On average, expect to pay $250-300 per square foot for a home addition. Simple projects may range from $200-250 per square foot. More elaborate additions with high-end finishes could cost $350+ per square foot.

Is adding a second story more expensive than building out?

Yes, second story additions tend to cost significantly more per square foot compared to building out additions. First floor additions average around $250 per square foot. Second story additions requiring added structural support and extensive stairway construction cost $300-350 per square foot.

How much does it cost to add a bedroom and bathroom?

A new bedroom addition costs approximately $100 to $250 per square foot. This factors in building interior and exterior walls, finishes, closets and electrical. Adding an attached bathroom addition costs around $50,000 to $75,000 including plumbing and finishes.

Is it cheaper to add on or move to a bigger house?

Whether it’s more affordable to add on or move depends on your market. On average, home additions cost $250-300 per square foot, while costs in your area to purchase a larger home could be higher per square foot. Carefully compare the costs in your specific situation.

Can I do any part of the addition myself to save money?

Prepping the worksite, demolishing existing structures, assisting with paint/finish work and landscaping after completion are ways to save on labor costs. However, additions require specialized skills for framing, roofing, electrical and HVAC work. Consult with contractors about safe DIY addition projects.

How much value does an addition add to my home?

According to the Remodeling 2021 Cost vs. Value Report, a home addition recoups around 68% of costs when you sell. Strategic renovations converting unfinished basement space into living area or adding a bathroom can boost value even more.

Should I take out a loan to finance the addition?

Yes, a home equity loan or line of credit offers affordable financing, with interest rates lower than high interest credit cards or personal loans. Many homeowners use equity loans up to $200k to finance additions. Extended 15 to 30 year terms keep payments low.

Does adding living space increase my property taxes?