22 Home Addition & ADU Statistics: Costs, Growth, and Resale Value (2026)
The numbers behind room additions, second stories, in-law suites, and ADUs in 2026, plus what they cost and what they return at resale.
Adding space to a home you already own has become one of the biggest trends in American housing. Freddie Mac research identified about 1.4 million single-family properties with accessory dwelling units, and homeowner spending on improvements and repairs is on track to reach a record level in 2026. The 22 verified statistics below cover what room additions, second stories, in-law suites, and ADUs cost, how fast the ADU market is growing, what they return at resale, and who is building them. If you are weighing extra square footage, our home addition services connect you with vetted pros.
Key Takeaways
- The average home addition costs about $51,032, with most projects between roughly $21,910 and $83,349 (Bankrate).
- An ADU averages roughly $180,000 nationally, ranging from about $40,000 to $360,000 by type and finish (SelfStorage.com).
- About 1.4 million US single-family homes have an ADU, and first-time ADU listings grew about 8.6% per year over the decade studied (Freddie Mac).
- In California, ADUs are now about 19% of new housing, with 83,865 permitted between 2016 and 2022 (California YIMBY).
- California homes with an ADU had a $1,064,000 median appraised value in 2023 versus $715,000 without one (FHFA).
- A master suite addition recoups only about 48% of its cost at resale (2025 Cost vs. Value Report).
- US homeowner improvement and repair spending is set to reach about $522 billion by the end of 2026 (Harvard JCHS).
What home additions and ADUs cost in 2026
1. The average home addition costs about $51,032
A typical home addition runs about $51,032, with most projects falling between roughly $21,910 and $83,349 depending on size, room type, and local labor, according to Bankrate. Because that range is so wide, a fixed-price estimate matters. Our financing options can help spread the cost.
2. A second-story addition averages around $175,000
Building up is the most expensive way to add space. A second-story addition averages about $175,000 and often runs $250 to $400 or more per square foot because of structural reinforcement, per Bankrate.
3. A bathroom addition averages about $35,000
Adding a bathroom costs roughly $35,000, or about $250 to $500 per square foot, driven by plumbing, waterproofing, and fixtures, according to Bankrate. It is one of the smaller additions by footprint but among the priciest per square foot.
4. A bedroom addition averages about $62,500
A bedroom addition averages near $62,500, generally $80 to $200 or more per square foot depending on finishes, per Bankrate. Bedrooms tend to cost less per square foot than kitchens or baths because they need less plumbing and specialized work.
5. An ADU averages roughly $180,000 nationally
Building an accessory dwelling unit averages about $180,000, with a broad range from $40,000 to $360,000, according to SelfStorage.com. A detached new build runs $200 to $400 per square foot, while attached units are somewhat less.
6. A garage conversion is the cheapest ADU path at $80,000 to $150,000
Turning an existing garage into a living unit typically costs $80,000 to $150,000, well below a detached new build, because the foundation and walls already exist, per SelfStorage.com. See our garage conversion services if that fits your lot.
Source: Bankrate and SelfStorage.com.
The ADU boom
7. About 1.4 million US single-family homes have an ADU
Freddie Mac identified roughly 1.4 million distinct single-family properties with an accessory dwelling unit, a stock that has grown steadily as homeowners add rental space and multigenerational housing, as reported by the Tiny Home Industry Association.
8. First-time ADU listings grew about 8.6% per year
Between 2009 and 2019, first-time ADU listings grew an average of 8.6% year over year, outpacing the broader housing market, according to Freddie Mac.
9. ADU home sales hit 70,000 in a single year, about 4.2% of listings
Home sales involving an ADU reached about 70,000 in 2019, roughly 4.2% of MLS sales, up from just 8,000 (1.1%) two decades earlier, per the Tiny Home Industry Association, citing Freddie Mac.
10. Four states hold about half of all US ADUs
California, Florida, Texas, and Georgia together account for about half of the roughly 1.4 million ADUs identified nationwide, according to Freddie Mac. ADU adoption tracks closely with state and local zoning reform.
11. California permitted 83,865 ADUs from 2016 to 2022
After California eased its ADU rules, the state permitted 83,865 ADUs between 2016 and 2022, a jump of more than 15,000% in annual permits over that span, according to California YIMBY.
12. ADUs are now about 19% of new housing in California
As of 2022, roughly 19% of all housing units produced in California, or nearly one in five, were accessory dwelling units, per California YIMBY. Other states are following as they relax their own zoning.
13. About 71% of homeowners are unfamiliar with ADUs
Awareness still lags demand: about 71% of survey respondents were unfamiliar with the ADU concept, yet 32% of those without one expressed interest in having one, according to Freddie Mac.
Source: Freddie Mac.
Resale value and ROI
14. California homes with an ADU appraised at $1,064,000 versus $715,000 without
In 2023, California single-family properties with an ADU had a median appraised value of about $1,064,000, compared with $715,000 for those without one, according to the Federal Housing Finance Agency. Some of that gap reflects larger lots and higher-value markets, not the ADU alone.
15. ADU properties appreciated 9.34% a year versus 7.65% without
From 2013 to 2023, California properties with an ADU appreciated at an annualized 9.34%, faster than the 7.65% for those without, per the FHFA.
16. A master suite addition recoups only about 48% of its cost
Additions rarely return their full cost at resale. A master suite addition recoups only about 48% of what it costs, based on the 2025 Cost vs. Value Report cited by AmeriSave. The payoff is more often in usable space or rental income than in resale dollars.
17. An ADU can bring in $1,500 to $3,500 a month in rent
In high-demand areas, an ADU can generate roughly $1,500 to $3,500 per month in rental income, and $800 to $1,500 in lower-cost regions, according to SelfStorage.com. That income stream is a key reason ADUs pencil out where a plain addition may not.
Source: FHFA.
Source: 2025 Cost vs. Value Report.
Who builds, permits, and appraises
18. ADUs rose from 1.9% to 3.0% of California appraisals
The share of California single-family appraisals that included an ADU climbed from about 1.9% in 2013 to 3.0% in 2022, an increase of nearly 60% since 2016, according to the FHFA. Appraisal data is one of the cleaner ways to track real ADU growth.
19. Portland, Dallas, Seattle, Los Angeles, and Miami lead metro ADU growth
Since 2015, Portland, Dallas, Seattle, Los Angeles, and Miami have posted double-digit annual ADU growth rates, the fastest among large US metros, per the Tiny Home Industry Association, citing Freddie Mac.
20. ADUs are valued at less than one-third of a primary residence
On their own, ADUs are typically valued at less than one-third the price of the traditional primary residence they sit beside, which is why they add usable space affordably rather than duplicating a full home, according to Freddie Mac. For a deeper look at renovation returns, see our home renovation statistics.
The remodeling market
21. Homeowner improvement and repair spending is set to reach about $522 billion
US homeowner spending on improvements and repairs is projected to reach about $522 billion by the end of 2026, a record level that includes room additions and other discretionary projects, according to Harvard's Joint Center for Housing Studies as reported by The MortgagePoint.
22. Remodeling growth is cooling from 2.9% to about 1.6%
Year-over-year growth in home improvement and repair spending is expected to slow from about 2.9% early in 2026 to roughly 1.6% by year end, a soft landing rather than a downturn, per The MortgagePoint, citing the JCHS LIRA. A slower market can mean more contractor availability for well-planned projects.
What this means for homeowners
- Additions vary enormously in price. A bathroom or bedroom addition can land near $35,000 to $62,500, while a second story or a full ADU often runs $175,000 or more, so scope and type drive the budget.
- ADUs are the fastest-growing way to add space. With about 1.4 million already in place and California building roughly one in five new units as ADUs, the trend is spreading as zoning loosens nationwide.
- Resale rarely returns the full cost, but the value shows up elsewhere. A master suite recoups about 48% at resale, while an ADU can earn $1,500 to $3,500 a month in rent and lift long-run appreciation.
- A garage conversion is often the lowest-cost entry point to a rentable unit, using walls and foundation you already have.
- Pro House Maintenance matches you with vetted, licensed and insured pros and provides free fixed-price estimates. See where we work on our service areas page and request an estimate when you are ready.
Frequently Asked Questions
How much does a home addition cost in 2026?
The average home addition costs about $51,032, with most projects landing between roughly $21,910 and $83,349, according to Bankrate. Cost depends heavily on type: a bathroom addition averages near $35,000, a bedroom about $62,500, and a second story around $175,000. Pro House Maintenance matches you with vetted, licensed and insured pros and gives free fixed-price estimates so you know the number before work begins.
How much does it cost to build an ADU?
An accessory dwelling unit averages roughly $180,000 nationally, ranging from about $40,000 to $360,000 depending on type and finishes, per SelfStorage.com. A garage conversion is usually the cheapest path at about $80,000 to $150,000, while a detached new build runs $200 to $400 per square foot. A free fixed-price estimate helps you compare options before committing.
How many homes in the US have ADUs?
Freddie Mac research identified about 1.4 million single-family properties with accessory dwelling units, and first-time ADU listings grew an average of 8.6 percent year over year across the decade studied. Just four states, California, Florida, Texas, and Georgia, account for about half of the nation total. ADU counts have climbed sharply as more states loosen zoning rules.
Does an ADU add value to my home?
In California, properties with an ADU had a median appraised value of about $1,064,000 in 2023 versus $715,000 for those without, and homes with ADUs appreciated faster over the prior decade, per the Federal Housing Finance Agency. Rental income of roughly $1,500 to $3,500 a month in high-demand areas can also offset the build cost over time.
Which addition gives the best return at resale?
Additions rarely return their full cost. A master suite addition recoups only about 48 percent of its cost at resale, based on the 2025 Cost vs. Value Report. Additions still pay off in usable space, rental income, or avoiding a move. Pro House Maintenance provides free fixed-price estimates from vetted, licensed and insured pros so you can weigh the numbers with confidence.