Affordable ADU Kits and Plans from prefabADU
prefabADU is a Bay Area-based accessory dwelling unit builder with over 16 years of experience in the ADU industry. As pioneers in the field, they have made it their mission to make affordable housing genuinely accessible. Their approach centers on a unique model: empowering homeowners to build their own ADU using comprehensive kits that include plans for permit submittal and an in-depth installation guide. This DIY-friendly system makes them one of the most affordable ADU contractors in the market, with options available for under $100K — and even one under $45K.
With over 170 completed units and recognition from industry award programs, this accessory dwelling unit builder has established a strong track record. Their state-approved plans are valid across all cities and counties in California, and their in-house team handles design, plan submission, and the full city approval process on behalf of the homeowner.
A Wide Range of ADU Plans to Suit Every Property
prefabADU offers 12 distinct ADU plans organized into four series, each designed to suit different lot sizes, budgets, and lifestyle needs:
- Micro Unit Plans (150–250 Sqft): The smallest code-compliant ADU designs available — not tiny homes built to RV code, but true accessory dwelling units built to full building code standards. Includes the Micro 150, Micro 200, and Micro 250.
- Mini Unit Plans (250–399 Sqft): Their most popular series, ideal for smaller inner-city lots. Despite their compact footprint, these plans feel surprisingly spacious. Includes The Becky (288 Sqft), The Elisabeth (300 Sqft), and The Jake (390 Sqft).
- Suite Unit Plans (400–649 Sqft): Well-suited for suburban lots and larger inner-city properties. This series includes their smallest two-bedroom plan. Options include The Pete (451 Sqft), The Andy (600 Sqft), and The David (640 Sqft).
- Villa Unit Plans (650–1,200 Sqft): Their largest plans, designed for estate properties, acreage, corner lots, and cul-de-sac configurations. Includes The Julie (700 Sqft), The Ryan (792 Sqft), and The Barbara (1,000 Sqft).
Each plan in their lineup is designed as a fully independent living space, complete with a full kitchen, bathroom, and laundry provisions — making them excellent granny flat, in-law suite, or backyard cottage solutions.
San Jose ADU Pilot Program and Financing Options
In partnership with the City of San Jose, prefabADU launched a pilot program aimed at scaling ADU production throughout the city. On May 12, 2021, Mayor Sam Liccardo announced a first-of-its-kind ADU loan tied to this initiative. The program offers a 0% interest loan for six months with no payments due during that period — a significant advantage given the limited financing options typically available in the ADU space.
Key features of the San Jose pilot program include:
- Fully permitted and installed ADU kits in 90 days
- Pre-approved plans ready to go — starting with The David (640 Sqft) and The Jake (390 Sqft)
- Expedited permit processing through the city's Department of Planning and Building
- Reduced fees — all plans are under 750 Sqft, eliminating impact fees
- Free online self-analysis tool via Symbium Build to check plan feasibility on any property
- Potential savings of up to 50% compared to market rate rents
What sets this detached ADU builder apart from a standard local contractor is their comprehensive, one-stop-shop approach. They provide complete design services in-house, handle plan submissions, offer in-house project valuation, and assist with financing — all under one roof. Homeowners know exactly what they are getting before construction begins, from windows to light switches, with samples and models available to guide decisions.
For homeowners looking for an affordable, streamlined path to building an accessory dwelling unit, prefabADU offers a well-structured process backed by years of industry expertise and a genuine commitment to making ADU construction accessible to more people.