Want to Design Your Own ADU? This Prefab Company Gives You the Tools

Welcome to Prefab Profiles, an ongoing series of interviews with people transforming how we build houses. From prefab tiny houses and modular cabin kits to entire homes ready to ship, their projects represent some of the best ideas in the industry. Do you know a prefab brand that should be on our radar? Get in touch!

Aleksis Bertoni and Tim Thimmaiah started building homes because they felt the two most common ways were falling short of modern expectations. Designing and constructing one residence at a time—essentially "reinventing the wheel" with each project—seemed archaic. Prefab construction was fast, but limited the ways a client could customize a home. But the duo saw a way to improve on the latter by developing new software.

They established Type Five in Northern California to build ADUs by using a system of design and construction they call "site-build modular." According to design director Ian Miley, on the front end, it lets clients fine tune their small spaces via the company’s website, where they can select everything from layouts, to finishes, to colorways. Then, a proprietary software inputs these choices to produce construction documents. Here, Type Five shares how its design process helped a family develop a backyard ADU.

Tell us about the most exciting project you’ve realized to date.

We built an ADU for clients who are the second generation to occupy the primary residence, which was passed down from their parents. The original home was a small farmhouse, but the family added an addition to it about a decade ago. When both parents began primarily working from home during the pandemic, and their two children got older, the family was suddenly facing a severe shortage of space. They considered selling the property and moving into a larger house, but decided to build a multipurpose ADU instead.

The new ADU functions as a work-from-home office, a guest home for in-laws, and as a kid’s room. Type Five’s system allowed for an expedited design and build process so the family could use it as soon as possible.

Nestled into a hillside at the base of Tilden Regional Park in Orinda, California, the L-shaped ADU balances a small footprint with functional interiors. The design maximizes views into the coastal oaks on the property and the more distant redwood-covered hills in both directions.

What does your base model cost and what does that pricing include? 

Our studio units are around 300 square feet and cost $200,000. This includes design, engineering, permitting, all site work, all construction, and appliances. Our standard finish package includes Bosch appliances, white oak hardwood flooring, Grohe plumbing fixtures, a Toto wall-hung toilet, and Corian solid surface countertops and shower walls. Type Five designs and builds ADUs all the way up to 1,200 square feet, which are priced at around $500,000 for a move-in ready home.