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Prefab ADUs
An ADU (accessory dwelling unit) is a second, smaller home on the same lot as a main house, such as a backyard cottage or granny flat, and many are now built in a factory and delivered ready to connect. Structofy has 125 ADU-size prefab homes from 35 builders, with a median listed price of $170,950 and a median size of 832 sq ft.
Numbers update automatically from Structofy listings. Last checked November 2, 2026.
Prefab ADUs on Structofy by the numbers
Prices are the builders' listed starting prices for the home itself. 68 of 125 listings show a price; the others say "contact for price" and are left out of the price figures. Price per square foot uses the 68 listings that show both a price and a size, and does not include land, foundation, delivery or setup. Structofy counts a listing as an ADU if it is 250 to 1,200 sq ft (not a tiny house, barn or manufactured/HUD-code home) or if the builder calls it an ADU. Local ADU size limits vary, so check your city's rules.
What prefab adus are
An ADU is a self-contained home with its own kitchen, bathroom and entrance, built on a lot that already has a house. People build them for aging parents, grown kids, guests, a home office or rental income. They go by many names, including backyard home, granny flat, in-law unit and casita.
Prefab ADUs are built in a factory as one or more finished modules or as panels, then delivered and set on a foundation. Because most of the work happens indoors, time in your backyard is often shorter than for a site-built unit, which matters when people are living in the main house.
Rules for ADUs are set by your state, city or county. They decide the largest size allowed, how close the unit can be to property lines, whether you need extra parking, and whether you can rent it out. Several states, including California, have passed laws that make ADUs easier to permit. Always check local rules before choosing a model.
What to look for
- Your local ADU size limit and setback rules.
- Whether the builder handles permits and site work, or only delivers the unit.
- Crane or truck access to your backyard.
- Utility connections: sewer, water and electric runs from the main house can be costly.
- Whether the unit is built to your state code (not just the HUD code).
- Total cost including foundation, delivery and hookups.
Prefab ADUs to compare
Abodu
Abodu One
The Abodu One is a 1-bedroom, 1-bath, 500 sq ft factory-built ADU from Abodu, all-electric and craned onto a p…
Alchemy Architects
SmartCabin Z1
Tech-integrated cabin with smart lighting and green energy.
Blu Homes
Origin 1000
The Origin 1000 epitomizes the essence of open concept living in a stunning manner. It has been thoughtfully c…
Connect Homes
Connect 1
Experience the latest trend in micro-living with Connect 1. Say hello to the easiest and most cost-effective w…
Country Carpenters
The Bungalow
1-bedroom bungalow with built-in solar, great for retirees.
DC Structures
Bandon Cabin Kit
The Bandon Cabin Kit from DC Structures is a cabin kit. Base configuration: 1,009 sq ft conditioned of 1,421 s…
Deltec Homes
Hideaway
Floorplan 32-A is meticulously crafted for optimal functionality, boasting a sturdy crawlspace foundation. Thi…
Den Outdoors
Barnhouse 1.1 Prefab Kit
The Barnhouse 1.1 is a 1-bedroom, 1-bath, 1,000 sq ft design from DEN Outdoors, sold as a panelized prefab kit…
Dvele
Fernie
Dvele revolutionizes the concept of healthy living. Our homes undergo a complete redesign, from the foundation…
EcoSteel
The Minimalist
While much of the industry relies on traditional stick-built construction, we stand out by partnering with car…
Honomobo
HONOMOBO HO2
The HO2 model offers flexible options with a choice between a 1-bedroom/1-bathroom or a 2-bedroom/1-bathroom l…
Ideabox
Origin
The Origin is a 1-bedroom, 1-bath, 560 sq ft factory-built modular home from ideabox, a modern prefab builder…
Top adu builders on Structofy
| Builder | Listings here |
|---|---|
| Champion Homes | 24 |
| Studio Shed | 14 |
| DC Structures | 10 |
| Avrame USA | 9 |
| Ideabox | 7 |
| Abodu | 6 |
| Method Homes | 5 |
| Den Outdoors | 5 |
| Lindal Cedar Homes | 4 |
| Blu Homes | 3 |
Guides that go deeper
- How much does a prefab home cost?Listed prices by home type and price per square foot.
- Prefab home costs beyond the priceLand, foundation, delivery, utilities and permits.
- How long does a prefab home take?The steps from contract to move-in.
- How much does a tiny house cost?Tiny house prices and sizes from real listings.
- How much does a backyard ADU cost?Prices for small backyard homes.
- All prefab home guidesEvery Structofy guide in one place.
Other home types
ADU questions
How much does a prefab ADU cost?
On Structofy, 68 ADU-size listings show a price, from $21,908 to $500,000, with a median of $170,950. The median price per square foot is $236, before site work, permits and hookups.
How big can an ADU be?
It depends on local rules; many places cap ADUs somewhere between about 800 and 1,200 sq ft. The median ADU-size listing on Structofy is 832 sq ft.
What is the difference between an ADU and a tiny house?
An ADU is defined by where it sits (a second home on a lot with a main house) and is usually on a foundation. A tiny house is defined by size and is often on wheels. Some tiny houses can be permitted as ADUs.
Can I rent out an ADU?
In many places yes, but some cities limit short-term rentals or require the owner to live on the property. Check your local rules.
Does Structofy sell ADUs?
No. Structofy is a directory. Open a listing or builder page and contact the builder.