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General Contractors on Thumbtack cost$10000 - $80000

National average price

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How much does a room addition cost?

The national average cost of a room addition ranges from $10,000-$80,000. Room addition project costs vary by number of square feet, material and construction costs, and remodel or repair work required on the existing structure to complete the add on.

A room addition expands the footprint of a home by building onto the existing floor plan. Room additions typically take less time, money and work than a complete home remodel. Common add ons include a home office, family room, expanded master bedroom suite, an additional bathroom, a walk-in closet or a guest room. Building an add on not only boosts your home's resale value, it's also a smart move for growing families or those accommodating an aging relative. If you're ready for more room, here's the bottom line on a new addition.

What's in This Cost Guide?

What Affects the Cost of a Room Addition?

Square feet, materils, finishes, zip code, and prep required all affect the cost of your new room addition. Most room additions have a price per square foot which is calculated by project scope, labor costs and materials. Room additions can be bare bones and economical or customized with high-end designs and finishes which will dramatically increase your cost per square foot. The need for architectural plans will also increase your cost estimates. Here’s a deeper dive into what affects the cost of a room addition.

Square Footage

The cost per square foot for new space can range from under $50 per square foot to $250 per square foot and higher. Most contractors offer an approximate price per square foot when bidding a house addition project. They determine how large the project is, what foundation work will need to take place, what type of frame needs to be built, whether the project requires extensive plumbing and electrical wiring, and how complex the job is.

Building Material Costs

The materials used to build a home can vary state by state, says RJ Nassar of Opus One Design Build. As an example, Nassar explains that homes in Florida are often built from concrete block while homes in Georgia are built on a concrete foundation with wood framing. Because of these regional material differences, the cost, just for the shell of a room addition, can be $10–$20+ more per square foot, depending on the region, what materials are required, and what type of skilled laborers (masons versus carpenters) are required.


Finishes are the final touches on your new family room, living room, or bathroom addition. Finishes are the type of carpet or floor you have installed, the trim you choose, and the type of tiles you want—be it high-end marble or affordable ceramic—in your master bath. The more luxurious the finishes, the higher your home addition cost will be.

Architectural plans

Some home additions require architectural drawings to properly equip contractors with building plans and to meet local building codes. If you want a second or third story addition, an architect may be required. Some architects charge a percentage of the total construction costs for plans, some charge a flat rate, and some charge by the hour. Average costs to hire an architect range between $875-$2,500, but can be higher depending on project scope. Learn more about architect costs.

Regional costs

The total price of a room addition depends on regional labor costs, business overhead and other area costs. Room additions in expensive cities such as Manhattan or San Francisco cost more because of higher labor costs and costs of doing business than smaller areas or cities with a lower cost of living.

How Much Does a Room Addition Cost?

The national average cost of a room addition can range from $10,000 to $80,000, or more, depending on how elaborate you want your new living space to be. A range of factors, such as how many new windows you want and if you need a concrete slab poured and if you prefer inexpensive asphalt shingles on the new roof or if you want high-priced copper shingles, all cause your price to raise or lower. Here are some examples of construction and finish costs per square foot from different parts of the country:

200-square-foot room addition: ~$10,000 from Renovations Your Way in Slidell, Louisiana

  • $50 per square foot is the starting price for a standard room addition with contractor grade finishes in Slidell, Louisiana
  • Pricing can increase $8,000–$15,000 or more, depending on the finishes
  • The average addition in Slidell, Louisiana, is a 10x19 room. The price per square foot includes the foundation, framing, drywall, interior and exterior paint, and standard flooring such as bedroom carpet
  • Customers supply any necessary fixtures

300-square-foot, upscale master bedroom expansion: ~$78,000 from YYB Construction in San Jose, California

  • $260 per square foot for a master bedroom and master bath expansion in Fremont, California
  • The price per square foot included foundation work, framing, drywall, stucco, interior and exterior paint, and flooring. The plumbing system was existing so the company extended it to the new bathroom
  • The project took approximately five weeks.
  • The customer paid an additional $5,000 for bathroom fixtures and flooring materials.

300-square-foot luxury kitchen addition: $81,000 from YYB Construction in San Jose, California

  • Approximately $270 per square foot for this addition in San Francisco
  • The price per square foot included foundation work, framing, drywall, exterior finish, interior and exterior paint, and extending the plumbing and electrical system
  • The customer paid for upgraded finishes, and YYB Construction installed them This labor was included in the price per square foot
  • The project expanded the existing kitchen by 300 square feet to create the client’s ideal space
  • The total project time was less than six weeks. One week was spent preparing for and pouring the foundation, one and a half weeks were spent framing, and two and a half weeks were spent finishing
  • The client selected top-of-the-line finishes such as white marble countertops, high-end wood cabinets and floors, and top-tier appliances such as a $7,500 refrigerator. The floors cost an additional $20,000—the client purchased floors separately, and YYB Construction installed them. The labor was included in the price per square foot of construction

How to Hire a General Contractor

If you want to hire a general contractor, it's important to do your research first. Unless you’re acting as project manager, hire a general contractor who will oversee all parts of the project, making sure there is an electrician, a drywall contractor, a flooring professional, painters, and all other necessary pros to complete your home addition. Whether you're doing a family room addition or a garage addition you will pay a significant remodel cost, so it’s wise to find a qualified pro you trust. It’s challenging to change contractors once you’ve signed a contract and paid a deposit, so doing your homework upfront pays off in the long run.

  • Verify contractor license. Most states require general contractors be licensed. As an example, the Washington State Department of Labor & Industries has an online license look up portal so you can verify your pro and ensure they don’t have any complaints lodged against them. Research your pro before hiring. For more information on smart hiring, check out our safety tips.
  • Ask for references and read reviews. A great website and friendly face shouldn’t be the sole reasons you hire a general contractor. Ask for references and read online reviews. Past experiences are important
  • Get clear on cash. After your free estimate, talk clearly about total project costs, what might cause the price to go up (unforeseen repairs, change orders mid-way through, etc.), and create a payment plan you both agree on. Never pay entirely upfront and be very wary of someone who asks for major money before completing work milestones
  • Sign a contract. Outline money, scope of work, timeline, and materials that will be used. The clearer the contract the fewer problems down the line
  • Stay in the loop. Hire a general contractor who communicates with you frequently and makes sure you understand what is taking place throughout all stages of the home addition

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