Room addition cost in 2026
Room addition costs $125 to $250 per square foot in 2026 for most homeowners, with a typical price near $190 per square foot.
What moves the price
- The size of the new space is the biggest driver, and the page prices it per square foot.
- The type of room matters, since kitchens and baths cost more than a simple bedroom.
- A second story addition costs more than building out on the ground.
- Where you live. Labor in big cities costs more than in small towns.
What is included
The range covers labor and materials for a typical room addition. It does not include permits unless the tables say so, or extra repairs found once work starts. Get a written quote that lists each part of the job.
Home addition price per square foot (by room addition size)
| Room addition size | Square footage | Average cost |
|---|---|---|
| 10x10 | 100 SF | $12,500 to $25,000 |
| 10x20 | 200 SF | $25,000 to $50,000 |
| 12x12 | 144 SF | $18,000 to $36,000 |
| 20x20 | 400 SF | $50,000 to $100,000 |
| 20x30 | 600 SF | $75,000 to $150,000 |
| 15x40 | 600 SF | $75,000 to $150,000 |
| 20x40 | 800 SF | $100,000 to $200,000 |
| 25x40 | 1,000 SF | $125,000 to $250,000 |
Average prices in US dollars. Source: HomeGuide.
House extension cost by type (average cost per square foot)
| Addition type | Average cost per square foot |
|---|---|
| Room addition | $125 to $250 |
| Bump-out room extension | $85 to $200 |
| ADU addition | $100 to $300 |
| Attic Conversion | $50 to $150 |
| Basement conversion | $50 to $100 |
| Garage conversion | $50 to $200 |
| Second-story addition | $200 to $500+ |
| Sunroom addition | $100 to $350 |
Average prices in US dollars. Source: HomeGuide.
Cost to add a room to a house (by room)
| Room | Size (square feet) | Average cost per square foot | Average total cost |
|---|---|---|---|
| Bathroom | 40 to 50 | $175 to $225 | $7,000 to $11,000 |
| Bedroom | 120 to 140 | $125 to $175 | $15,000 to $25,000 |
| Family room / Flex room | 200 to 225 | $125 to $175 | $25,000 to $40,000 |
| Kitchen | 100 to 200 | $200 to $250 | $20,000 to $50,000 |
| Primary suite | 300 to 600 | $150 to $225 | $45,000 to $135,000 |
| Sunroom | 150 to 300 | $100 to $350 | $15,000 to $105,000 |
Average prices in US dollars. Source: HomeGuide.
Why this costs more in 2026
Labor is the biggest part of most home jobs, and skilled trade pay keeps rising. Many materials and parts are imported, and freight went up after the oil shock that began with the Iran war in February 2026. Steel, copper, aluminum and resin all cost more too, so quotes for room addition are higher than they were a few years ago.
Ways to pay less
- Converting an attic, basement, or garage usually costs less per square foot than building new space.
- Keeping the addition smaller and simpler also lowers the bill.
- Get at least three written quotes and compare them line by line.
Where the price comes from
The range on this page comes from one named price guide. We read every number on its page and show the date it was last updated.
- HomeGuide: Room addition cost guide, page dated January 8, 2024
Common questions
How much does this cost in 2026?
Room addition costs $125 to $250 per square foot in 2026 for most homeowners, with a typical price near $190 per square foot. Most people pay about $190 per square foot. The low end is $125 and the high end is $250.
What changes the price the most?
The biggest factors are: The size of the new space is the biggest driver, and the page prices it per square foot; The type of room matters, since kitchens and baths cost more than a simple bedroom; A second story addition costs more than building out on the ground.
How can I pay less?
Converting an attic, basement, or garage usually costs less per square foot than building new space. Keeping the addition smaller and simpler also lowers the bill. Get at least three written quotes and compare them line by line.
Where do these numbers come from?
From one named price guide, HomeGuide. It is linked on this page with the date it was last updated.
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