How Much Does It Cost to Add on a Room?

Kelly Weimert
Written by Kelly Weimert
Reviewed by Robert Tschudi
Updated January 24, 2022
Interior of a cosy bedroom on a sunny day
Photo: Klaus Vedfelt / DigitalVision / Getty Images

The typical cost to add on a room is $20,900 to $72,600

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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. This guide outlines how much it costs to add a room to a house based on factors like where you live and what type and size of room you're building.

How Much Does It Cost to Add a Room to a House?

It typically costs between $20,900 and $72,600 to add on a room, but the cost can reach as high as $125,000 or go as low as $5,600, depending on things like materials, labor, and room type. The cost can also vary by location and whether or not you choose to do it yourself.

How Much Does It Cost to Add on a Room by Square Foot?

Your new room's size is one 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

How Much Does It Cost to Add on a Room Near You?

Room addition costs can also vary quite a bit based on where you live.

Room Addition Costs by City

CityCost
Austin, Texas$12,768–$42,567
Charlotte, N.C$17,177–$52,032
Chicago$27,604–$97,285
Dallas$22,494–$55,565
Denver$22,365–$77,997
Los Angeles$57,916–$130,081
New York$27,853–$111,169
Portland, Oregon$21,088–$62,629
Seattle$23,528–$84,744
Washington, D.C.$41,146–$120,176

How Much Does It Cost to Add on a Room Yourself?

Typically, labor costs for a room addition amount to 30% to 50% of the project’s overall cost. You can reduce or eliminate these costs by building part or all of the room yourself. For instance, if you decide to do the demolition yourself, you can potentially save $500 or more in labor charges.

You can also save money by painting the walls, laying flooring, and installing built-in furniture like vanities on your own. However, these projects are time-consuming and require skill, so you should weigh labor costs against just how much time you're willing to spend on the project, as well as whether you have the skills to complete it to your standards. You’re the one who’ll be seeing it every day, after all.

Room Addition Cost Breakdown

From installing plumbing and laying flooring to getting building permits, adding on a room requires many steps, and many of these components cost money. If you're curious about where you can save money through a DIY approach or you simply wonder where all of your money will go, here's a simple cost breakdown for an average-sized room.

  • Bathroom plumbing installation: $1,500–$4,000

  • Electrical: $320

  • Wood flooring: $800–$1,000

  • Carpet: $350

  • Drywall: $400–$600

  • Permitting: $400–$1,850

  • Non-load-bearing wall demolition: $300–$1,000

  • Load-bearing wall demolition: $1,200–$10,000

  • Roof materials: $500–$5,000

  • Roof framing: $700–$900

  • Foundation installation: $4,000–$12,000

  • Foundation materials: $400–$700

How Much Does It Cost to Add on a Room by Type?

A construction site of a room
Photo: Comstock / Stockbyte / Getty Images

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.

Cost to Add a Bathroom

Speaking of bathrooms, if you're looking to add a new one, then you'll likely pay anywhere from $20,000 to $90,000, with the average cost of a 100-square-foot bathroom being about $75,000

Even though bathroom additions cost more than some other types of rooms due to plumbing and fixture costs, they can also significantly increase the value of your home. In fact, depending on where you live, you can expect a 47% to 67% return on your bathroom addition investment.

Cost to Build a Primary Suite: Bedroom and Bathroom

Primary suites include a bedroom and a bathroom, so they're among the most expensive types of room additions. Costs for this project typically range from $25,000 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.

Cost to Add a Kitchen

Like bathrooms, new kitchens require plumbing work, which adds costs. You'll also have to pay to install appliances, like your refrigerator and oven, unless you plan to take care of that yourself. Depending on your appliances, plumbing needs, kitchen size, and materials, the average cost of a 200-square-foot kitchen ranges from $48,000 to $95,000

Cost to Add a Living Room or Dining Room

Because living room and dining room additions don't typically have plumbing or appliance needs, they tend to cost less to build than kitchens and bathrooms. The average cost of an 18’ x 12’ living or dining room ranges from $17,300 to $43,200. Adding elements like built-in furniture and high-end finishes will take you closer to the top of this range.

Cost to Add a Room Above the Garage

Adding a bonus room above the garage usually costs around $115 per square foot, with the average cost amounting to about $45,000. However, the cost of this particular project varies quite a bit based on factors like whether or not 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 to the overall cost. 

Cost to Add a Laundry Room

Because laundry rooms tend to be among the smallest rooms in the house, they're also some of the least expensive additions. Most people pay between $5,000 and $7,000 to add 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.

Cost to Add a Mudroom

Thanks to their typically small size and nonexistent plumbing requirements, mudrooms are usually the cheapest rooms to add on. A 36-square-foot mudroom typically costs around $3,600 to $7,200, depending on the type of flooring and storage you add.

Cost to Add a Sunroom

Sunrooms can be very basic, only designed for use during two or three seasons, or they can have extensive electrical, heating, and cooling needs. This wide variation means that the costs also vary considerably. Installing a basic, 200-square-foot three-season sunroom usually costs around $25,000, while a more extensive, all-season sunroom of the same size can cost $80,000 or more.

What Factors Influence the Cost of a Room Addition?

When budgeting for a room addition, there are many potential costs to consider, including expenses for architectural services, foundation materials, and flooring. 

Architectural Services

If you want your addition to match the rest of your house, then you might need to hire a local architect, which typically costs $2,000 to $8,400.

Demolition and Site Prep

It usually costs around $1,300 to $5,100 to excavate, demolish, and prepare a construction site to build on.

Foundation Materials

Building a first-story addition requires laying a new foundation, which can cost you around $4,200 to $13,200.

Roofing

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. 

Support Beams

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.”

Drywall

For walls to look like, well, walls, they need drywall, which costs around $1 to $3 per square foot

Door and Window Installation

Doors typically cost around $1,000 to purchase and install, while windows range from $235 to $2,500, depending on the style and any customization. 

Flooring

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. 

HVAC Installation

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.”

FAQs About Room Additions

What’s the first thing to do when planning a room addition?

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 such as:

  • Easements

  • Environmental 

  • Water or /flood zone 

  • Restrictive HOA covenants

  • Historic area restrictions

  • Septic system tank size (for kitchens and bathrooms)

Many homeowners start the planning process by having the property surveyed, which costs from $300 to $600.

Will a new addition increase my home's value?

The short answer is yes. Room additions usually 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.

Should I build an addition myself or hire a professional?

Given that labor amounts to around 30% to 50% of room addition costs, building an addition yourself can definitely save you money. However, construction requires time, knowledge, and skill, so before deciding to take it on yourself, you'll want to research all of the steps you need to take and weigh whether you have the time and expertise required to complete the project to your standards. 

Rather than build the whole addition yourself, you can also save money by only working on certain components yourself, such as daily site clean-up, painting the walls, landscaping, and installing flooring, depending on what you're comfortable with. 

What should I consider when adding a room to my house?

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 establish a realistic budget before committing to the project. 

If you decide to tackle the project yourself, then make sure you have the time and resources it takes to complete it. It can be challenging to balance your other responsibilities with a DIY construction project, so it's a good idea to create a schedule for yourself to ensure you have the time you need. 

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. 

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