CLT modular methods is represented here in Anderson Anderson’s design and engineering for mass timber accessory dwelling units (ADU’s) in California. These relatively small, free-standing modular “apartment” units are currently fabricated at a start-up factory space in Oakland, California. They are entirely prefabricated off site and then lifted by crane into place into a backyard or other location where an additional household unit can be inserted. The intention of such units is to densify typical single-family home neighborhoods, bringing affordable housing into the community and providing rental income for homeowners. This approach to affordable housing production has been a big focus of local government programs and planning efforts, with zoning code revisions allowing ADU’s on single-family sites throughout the state of California, and other places with urgent needs for more options in affordable housing.

This mass timber version of a modular ADU is the first of its kind, offering a quality of construction and environmentally positive approach beyond other offerings in this increasingly important sector of housing production. In this case, the entire structural module and primary enclosure is constructed with just six massive, cross-laminated timber panels–four wall panels, a floor panel and a roof panel. While simplifying many aspects of the building process, this system requires a great deal of sophisticated detailing and engineering to produce a strong, environmentally responsive, healthy and comfortable living unit that can be safely transported whole to the building site. The system affords a wide range of design options, such that the unique qualities of this ADU are not defined by a particular style or image, but by the system itself, the quality of the components and incomparable solidity, quietness and security.

In addition to the ADU shown here, which is currently in production and available for purchase, the system includes alternate plans, roof lines, surfaces and finishes, as well as more significant variants for related classroom units and for multi-story residential, hospitality and commercial programs. In a sense, this ADU represents an example of one cell in Anderson Anderson’s mass timber modular systems that can be combined to make a wide variety of buildings.

Rent the BackYard is the name of a California manufacturer currently producing this modular dwelling unit design for sale. The company focuses on building accessory dwelling units for single-family residential properties in California. The company’s modular design system, unit design and production methods have been designed by Anderson Anderson Architecture, which is also an investor in the company. The following is descriptive text used by RTBY to describe the modular CLT accessory dwelling unit (ADU) product. RTB currently has completed initial prototyping and California prefabricated housing factory production approval, with units currently under construction in the Oakland factory. Here is a link to the Rent the Backyard website, with more information about availability, process and costs.