A home addition is one of the most impactful ways to increase your living space and home value. But it's also one of the most complex and expensive projects a homeowner can undertake. Here's how to budget accurately.
Average Home Addition Cost Per Square Foot
| Addition Type | Cost per Square Foot |
|---|---|
| Basic room addition (bedroom) | $100–$200 |
| Bathroom addition | $200–$400 |
| Kitchen expansion | $300–$500 |
| Second story addition | $150–$350 |
| Sunroom / 3-season room | $80–$180 |
| Garage conversion to living space | $50–$150 |
| In-law suite | $175–$350 |
What Drives Home Addition Costs
- Foundation type — Slab is cheaper than crawl space or full basement
- Roof tie-in — Connecting to an existing roofline adds complexity and cost
- Plumbing and electrical — Kitchens and bathrooms cost more due to utility extensions
- Permits and inspections — Add $1,000–$5,000 depending on scope
- Matching existing finishes — Matching original materials can be difficult and expensive
Estimate Your Home Addition Cost
Enter your addition size and type to get an instant cost range.
Estimate Addition Cost →Permits and HOA Approval
Nearly all home additions require a building permit. Unpermitted additions can cause major problems when selling your home — buyers' lenders often require permits to be pulled retroactively, which is far more expensive. Always permit your work.
Home Addition vs Moving
In many markets, a home addition costs less than buying a larger home when you factor in moving costs, real estate commissions, and higher mortgage payments. If you love your neighborhood and lot, an addition is worth serious consideration.