How Much Does a Room Addition Cost? [2025 Data]

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.

How Much Does It Cost to Add a Room by Size?

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. 

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

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 Bedroom

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 bedroom can increase your home’s value and make it more appealing to potential buyers when it comes time to sell.

Cost to Add a Bathroom

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. 

Cost to Build a Bedroom and Bathroom (Primary Suite)

The cost to build a primary bedroom with a bathroom ranges from $30,000 to $100,000, but it 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

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.

Cost to “Bump Out” a Room

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.

Cost to Add a Dining Room

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.

Cost to Finish a Basement

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. 

Cost to Finish an Attic

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. 

Cost to Convert a Garage

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. 

Cost to Add a Room Above the Garage

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. 

Cost to Add a Laundry Room

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.

Cost to Add a Mudroom or Entryway

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.

Cost to Add a Sunroom

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.

Cost to Add In-Law Suite

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 its size and complexity. Another option for an in-law or guest suite to consider is building an accessory dwelling unit (ADU) or an addition.

Cost to Hire a General Contractor to Add a Room

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.

Electrician Costs

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. Some other tasks an electrician may perform include:

• Outlet installation: $100–$450 each

• Light switch installation: $60–$300 each

• Light fixture installation: $150–$900 each

Plumber Costs

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. Here’s a breakdown of some of the costs for plumbing projects:

• Toilet installation: $225–$530

• Sink installation: $215–$660

• Shower installation: $1,100–$8,500

Additional Contractors to Consider Hiring 

Depending on the specifics of your project, you may need to hire additional contractors to complete certain tasks. Some other contractors you should consider hiring include:

• HVAC installer: $2,000–$3,000

• Structural engineer: $70–$250 per hour

• Architect: $125–$250 per hour

• Foundation contractor: $5–$37 per sq. ft.

Room Addition Cost Factors

Room Addition Cost Factors

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

Permits

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. 

Demolition and Site Prep

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

Materials

Materials costs will significantly affect your total project cost. From structural materials to finishing touches, the quality and availability of the materials you use in your addition will affect how much you pay. High prices from material shortages, supply chain interruptions, or transportation issues can cause unexpected hits to your budget.

Inspections

In order for your addition to meet local codes and be built legally, you’ll need to have it inspected. A local official may inspect the work in stages, both during construction and once it’s completed. An inspection will cost an average of $200 to $300 for an addition. 

Framing

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. 

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.

Door and Window Installation

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

Drywall

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

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. 

DIY vs. Hiring a Pro

Adding a room is a complex and time-consuming job that should be handled by a professional who builds home additions. 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. 

Ways to Save Money on Room Addition Costs

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 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. 

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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