A granny flat is an ADU built for family.

A granny flat is a permitted, self-contained second home on a lot that already has a house: its own kitchen, its own full bath, its own entrance. The name says who it is built for — a parent or a grandparent — not a legal category. Government Code §66313 calls the same building an accessory dwelling unit; homeowners also say casita, backyard cottage or in-law suite.

Yes. Granny flat is the everyday word; accessory dwelling unit, or ADU, is what state law and the permit counter call it, and there is one category. It is reviewed on the same ministerial path, under the same setback and floor-area rules, whether a parent, a grown child or a tenant lives in it.

It is priced by how it is built, not by who lives in it. A garage conversion typically runs $85K – $170K+, a Junior ADU $135K – $220K+, an attached ADU $200K – $350K+, and a detached ADU $245K – $440K+ — Avorino’s published Orange County ranges. Run the ADU cost estimator for a calibrated range on your own lot.

Government Code §66314 sets the ceilings a city may impose: “The total floor area for a detached accessory dwelling unit shall not exceed 1,200 square feet,” and an attached one “shall not exceed 50 percent of the existing primary dwelling.” State law also allows one detached new-construction unit of up to 800 square feet with four-foot side and rear setbacks (§66323), and §66313 caps a junior ADU at 500 square feet inside the house. An Avorino detached unit finishes at typically 500 – 1,200 sqft.

Yes, and it is usually the shortest route. §66314(d)(7) provides that “No setback shall be required for an existing living area or accessory structure ... that is converted to an accessory dwelling unit,” and §66314(d)(11) bars a city from requiring replacement of the offstreet parking a converted garage held. A garage conversion typically runs $85K – $170K+ over 4–6+ mo, at 350 – 600 sqft.

For a standard ADU, no: §66315 bars a local agency from imposing “an owner-occupant requirement,” though it may require “rentals of terms 30 days or longer.” A junior ADU is the exception, and a narrower one than most sites state — §66333(b) requires owner-occupancy only “If the junior accessory dwelling unit has shared sanitation facilities with the existing structure,” and even then the owner may live in either portion; a junior ADU with its own sanitation carries no such requirement.

Renting is the ordinary path: under §66315 a city may require only “rentals of terms 30 days or longer,” so a month-to-month or annual tenancy is what the statute contemplates and short stays are what cities restrict. Selling it separately does not follow — a junior ADU carries a recorded deed restriction that must include “A prohibition on the sale of the junior accessory dwelling unit separate from the sale of the single-family residence” (§66333(c)). For a standard ADU the rule is §66314(d)(1): the unit may be rented separate from the primary residence, but shall not be sold or otherwise conveyed separate from it, subject to the separate-conveyance exceptions elsewhere in the chapter.

Avorino does: a granny flat is a permitted ADU, and Avorino builds them across 37 Orange County cities under California General-B License #1107538. If you already have the lot in mind, run the cost estimator for a price range, or send us the address and we will give you a plain read on what fits.