Company presents code-compliant prefabricated roundhouses as alternative ADUs; staff to consider preapproval options

At an information item on Aug. 22, 2025, Sarah Da Silva, general manager of Living in Tent Roundhouse Company (Grass Valley), presented a prefabricated circular dwelling — described by the company as a “roundhouse” — as an alternative housing type that can meet California building and energy codes and be used as an accessory dwelling unit (ADU) or primary residence. Da Silva said the company’s standard product range includes 16-, 20-, 24- and 32-foot diameters, and that the 32-foot model begins at about 767 internal square feet; taller wall and loft options are available. She said the manufacturer’s assembly uses rigid foam insulation, double-pane windows and a conditioned roof assembly; the structural plan sets and a structural-engineer review have been prepared to withstand wind, seismic and a baseline 175 psf snow load. "We call the roundhouse to not confuse the language with yurts," Da Silva said, explaining the company adopted the name to avoid the non‑habitable connotations sometimes associated with “yurt” and to emphasize code compliance. Nut graf: The presentation addressed two county priorities — increasing affordable housing options and clarifying the building-permit path for alternative housing types — by offering pre‑engineered plan sets, a factory-built shell (roof and walls) and on‑call permitting support intended to streamline local review. Da Silva said the company provides stamped generic plan sets, an Oregon structural engineer familiar with the system, an in‑house home designer who has secured approvals in Nevada County and a packaged shell that typically reduces on-site inspection counts from 15–16 for conventional builds to roughly four or five. She also described product details: a 40‑mil Duralast membrane or 22‑gauge metal roof; birch interior sheathing; bamboo compression rings and sapele‑grade trim; and the option of foundation types ranging from post‑and‑pier to a concrete slab. Da Silva said the company’s approach targets lower cost and owner‑builder accessibility while meeting energy (Title 24) and, where used, Housing & Community Development (Title 25) requirements. On sprinklers, Da Silva said a Title 25 pathway can exempt some requirements for owner‑builder or limited‑use scenarios: "Title 25 actually exempts the fire sprinklers from being required as well as the solar and any energy-efficiency calcs," she said; county staff clarified that Title 25 adoption is part of the building-code update underway and has not yet been adopted locally. Commissioners and staff asked technical follow-ups about fire‑protection options, foundation types, insulation and snow loads; one commissioner said a local ADU of the type presented already exists on a neighbor’s property. Da Silva offered to provide sample preapproved layouts and follow up with building‑department staff if the county wanted to include the company’s plans in a preapproved packet for ADUs or alternative dwellings. Ending note: Planning and building staff said they have Da Silva’s contact information and will consider how the county’s building-code update (including possible Title 25 adoption) could incorporate preapproved plan sets or templates to streamline permitting for code‑compliant prefabricated units.