How Much Does a Room Addition Cost? [2026 Data]

In 2026, the national average cost for a room addition is $48,000, though most homeowners spend between $20,900 and $72,600, depending on materials, labor, and room type. Location, room size, and whether you hire a contractor or take on some of the work yourself all contribute to that spread.

Room Addition Costs by Size: How Much Does It Cost by Square Foot?

Room size is one of the biggest drivers of your total room addition cost, with larger spaces requiring more materials, labor, and time. Costs vary significantly depending on the square footage you add, so the table below breaks down average prices by room size.

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

The type of room you add has a direct impact on your total cost, since each room comes with its own installation requirements. Adding a primary suite with an attached bathroom, for example, means budgeting for bathroom plumbing that typically runs $1,500 to $4,000 on top of the base addition cost.

Cost to Add a Bedroom

A bedroom addition costs $50,000 on average, though the final price depends heavily on size and features. Larger bedrooms with extra windows and walk-in closets push costs toward the higher end, while smaller guest or kids' rooms are considerably more affordable. Adding a bedroom can increase your home's value and make the property more appealing to buyers when you're ready to sell.

Cost to Add a Bathroom

Adding a new bathroom costs $22,000 on average and delivers a strong return, with homeowners seeing a 47% to 67% ROI depending on location. If a full bathroom exceeds your budget, a half bathroom with just a sink and toilet is a more affordable option at $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, though large suites or high-end finishes like custom cabinetry and marble countertops can push the total well over $100,000.

Cost to Add a Kitchen

A new kitchen installation costs between $35,000 and $95,000, with most projects averaging around $65,000. Features like islands and appliances account for a significant share of that cost, so there are meaningful opportunities to trim expenses by scaling back on those elements.

Cost to "Bump Out" a Room

A bump-out addition expands an existing room and often adds new amenities, with bump-out additions costing $4,000 to $30,000 depending on how much space you're adding. Because bump-outs typically involve minimal electrical work and no plumbing, they tend to be more affordable than most other addition types.

Cost to Add a Dining Room

Adding a separate dining room typically costs between $3,000 and $50,000, with the wide range reflecting differences in size and finish level. High-end lighting, chandeliers, a wet bar, and similar amenities can push the total toward the upper end of that range.

Cost to Finish a Basement

Finishing a basement means converting an unfinished space into a fully livable room with lighting, heating, and other essentials, and the cost to finish a basement ranges from $15,000 to $75,000 depending on the scope of work. A half-finished basement requires fewer materials and sits toward the lower end of that range.

Cost to Finish an Attic

Finishing an attic typically costs between $10,000 and $50,000 for the cost of finishing an attic, making it a simpler and generally less expensive project than finishing a basement. Most homeowners convert the space into an extra bedroom, home office, or lounging area.

Cost to Convert a Garage

Converting a garage to a room costs between $6,000 and $27,000, making it one of the more budget-friendly addition options. Garages work well as game rooms, extra bedrooms, or home offices, and the lower cost reflects the reduced wiring and plumbing work typically required.

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 totaling about $45,000. Costs vary based on factors like staircase construction or structural changes to the existing garage, and significant structural work can add $10,000 to $40,000 or more to the total.

Cost to Add a Laundry Room

The cost of adding a laundry room typically falls between $5,000 and $7,000 for most homeowners. Upgrading appliances, adding a sink, or installing extra shelving can push the total to $10,000 or more.

Cost to Add a Mudroom or Entryway

Mudrooms are among the least expensive rooms to add, with a 36-square-foot mudroom or new entryway costing around $3,600 to $7,200 depending on flooring and storage choices. Their small footprint and lack of plumbing requirements keep costs lower than most other addition types.

Cost to Add a Sunroom

A window-filled sunroom costs between $10,000 and $40,000 for an average three-season build, depending on construction type. The space can serve as a play area, a second living room, or even a small indoor greenhouse.

Cost to Add In-Law Suite

Adding an in-law suite costs $44,000 to $100,000 depending on size and complexity, with privacy and access considerations often adding to the total. If that range exceeds your budget, building an accessory dwelling unit (ADU) or an addition is another option worth exploring for an in-law or guest suite.

How Much Does It Cost to Hire a General Contractor to Add a Room?

A local home addition general contractor manages labor, materials, and scheduling for your project, and hiring a general contractor typically costs $300 to $500 per day on top of materials, though some contractors charge a percentage-based fee of 10% to 20% of the total project cost instead. 

Most room additions also require specialized subcontractors for work like plumbing, roofing, and wiring, which the general contractor will coordinate and which adds to your overall budget. Many projects also call for an architect during the planning stages, costing $2,000 to $8,400.

How Much Does It Cost to Hire an Electrician for a Room Addition?

Electrical installation is part of nearly any home addition cost, with wiring for outlets and lighting running $2 to $4 per square foot. If the existing electrical system needs upgrades to meet building code, such as replacing an outdated service panel, budget an average additional $1,150. Here's how room addition electrician costs costs compare by task:

• Outlet installation: $100 to $450 each

• Light switch installation: $60 to $300 each

• Light fixture installation: $150 to $900 each

How Much Does It Cost to Hire a Plumber for a Bathroom Addition?

If your room addition includes a bathroom, plumbing costs will range from $1,000 to $10,000 depending on the complexity of the work and how the new space ties into your home's existing system. Here's how room addition plumber costs costs compare by task:

• Toilet installation: $225 to $530

• Sink installation: $215 to $660

• Shower installation: $1,100 to $8,500

Which Additional Contractors Should I Consider Hiring?

Depending on your project's scope, you may need to hire additional specialists beyond a general contractor, and costs vary by trade and project complexity.

• HVAC installer: $2,000 to $3,000

• Structural engineer: $70 to $250 per hour

• Architect: $125 to $250 per hour

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

Room Addition Cost Factors: What Determines the Price?

See how room addition cost factors costs break down below:

Permits

Building permits for a room addition cost between $150 to $2,000 in most situations, varying by location and project size. When you hire a contractor, obtaining permits and meeting their requirements is typically handled by the contractor and included in your contract.

Demolition and Site Prep

Excavating, demolishing, and preparing a construction site typically costs around $1,300 to $5,100 before any building begins.

Materials

Materials costs have a significant impact on your total project budget, with quality and availability both influencing what you pay from structural components to finishing touches. Material shortages, supply chain disruptions, or transportation issues can cause unexpected price increases, so it's worth building some flexibility into your budget.

Inspections

An inspection will cost an average of $200 to $300 for a room addition, and inspections are required for your project to meet local codes and be built legally. A local official may inspect the work in stages, both during construction and after completion.

Framing

Framing is included in every home renovation contract for a room addition, with costs averaging $6 to $10 per square foot of the new space. The final price depends on project complexity and how the new structure connects to the existing home.

Roofing

Laying a new roof typically costs around $80 to $100 per square foot, so roofing expenses scale directly with the size of your addition.

Support Beams

Support beams are essential for keeping your addition's walls structurally sound, and installation typically costs around $1,150 to $4,600.

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

Drywall is a necessary finish for any new room addition and costs around $1 to $3 per square foot.

Flooring

Flooring for a room addition typically ranges from $1,500 to $4,500 depending on the material you choose. Wood flooring sits at the higher end of that range, while vinyl and linoleum options are generally the most affordable.

Why You Should Hire a Room Addition Construction Pro

Adding an additional room onto your home is a major structural endeavor, involving a long list of requirements, including electrical, plumbing, insulation, painting, and framing. With such a complex list of tasks, it's important to hire a professional contractor for your room addition project.

Here's why it's ideal to hire a construction pro

While it will increase the costs of your renovation, here's why you should hire a professional:

• A professional has access to the best materials and tools, ensuring the highest quality work on your project.

• They have the experience and insight to keep the project on a tight, efficient schedule, even with all the moving pieces.

• It will reduce the risks of dangerous mistakes, both by keeping your home safe and eliminating potential costs from errors.

• They will handle zoning, permits, and required inspections correctly and without delaying your project's timeline.

If you want to DIY your room addition

The structural complexity of adding another room to your home definitely calls for professional help to protect you and your home from potentially hazardous errors. However, you can DIY certain aspects of the project to keep costs lower:

• Prep with measurements, zoning information, and other details about your home to cut down on time (and therefore costs) with your contractors.

• DIY painting your walls and trim can save anywhere from $300 to $800, depending on the size of the space.

• Handle flooring installation yourself with DIY tile or vinyl wood kits to save money on both materials and labor.

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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