Why the state sets the floor here
A city ordinance has to leave certain things open. Government Code 66314 requires an ordinance to allow an attached unit of up to 50 percent of the existing primary dwelling and a detached unit of up to 1,200 square feet, to ask no setback at all where an existing living area or accessory structure is converted, and no more than four feet from the side and rear lot lines for a new one. Fire sprinklers cannot be required if they are not required for the primary residence.
The review runs on a clock rather than a hearing. Applications are considered and approved ministerially, with no discretionary review. Completeness is determined no later than 15 business days after the agency receives the application, and it approves or denies within 60 days of receiving a completed application where a dwelling already stands on the lot. Past that, section 66317 deems the application approved.
A garage is the most common starting point, and it has its own rules. Where a garage, carport, covered parking structure or uncovered space is demolished in conjunction with building a unit, or converted into one, the agency cannot require those off-street spaces to be replaced, and the demolition permit for a detached garage being replaced is reviewed with the application and issued at the same time. Section 66323 also allows one unit within existing or proposed space on a single-family lot, with an expansion of up to 150 square feet beyond the existing accessory structure for ingress and egress.
The energy path depends on which of those three routes the unit takes. A unit that shares no common walls and is a new detached structure is a newly constructed residential building, with the full mandatory and prescriptive requirements behind it. One created within existing conditioned space is an alteration, and one built over an existing unconditioned space such as a detached garage is an addition. The compliance manual separates the three.
What ADU builder includes
The lot is walked with the primary dwelling, the garage or accessory structure, the setbacks and the access to it. The unit is then placed on the route it qualifies for, because a conversion, a build over a garage and a new detached unit are three different projects on paper.
The unit is drawn inside what the ordinance must allow, with the state floors on interior livable space, the four-foot side and rear setbacks and the height limits as the outer frame.
Plans and the energy documents are prepared for the route the unit takes, and a septic lot may be asked for a percolation test completed within the last five years.
The assigned contractor lodges the application and pulls the permit, with any garage demolition permit going in alongside it rather than afterwards.
The written estimate is set out in line items and the contract carries the payment schedule, the change-order rule and approximate start and completion dates.
The unit is built in stages, an inspection is requested before permitted work is covered, and the final closes on the alarms, the fixtures and the permit card.
An accessory dwelling unit is decided against a clock, not against an opinion. The application is considered ministerially, without a hearing, and an agency that has neither approved nor denied a complete one within 60 days leaves it deemed approved.
Where accessory dwelling units go
Lots with a detached garage
The structure is already there, the setback rule is relaxed for converting it, and building over it counts as an addition for the energy documents.
Tract homes with attached garages
An attached garage is part of the residence, so converting it can produce a junior unit inside the walls of the house rather than a separate building.
Lots with room at the back
A new detached unit is a newly constructed building in energy terms, and the ordinance has to allow at least the state's floor on size and height.
Houses with unused interior space
A unit created within existing conditioned space is an alteration, which is the lightest of the three energy paths and the shortest build.
Lots on septic
Where the lot is not on a sewer, the agency may require a percolation test completed within the last five years before the application is complete.
Pre-1978 houses and garages
Converting a painted structure disturbs painted surfaces, so the lead renovation rules run over the conversion work as they would over any remodel.
Questions about ADU builder
Completeness is answered no later than 15 business days after the agency receives the application, and a complete application is approved or denied within 60 days where a dwelling already stands on the lot. If neither happens, it is deemed approved.
A converted existing living area or accessory structure cannot be made to meet a setback, and one unit within the existing or proposed space of a single-family lot is a ministerial category in its own right, with up to 150 square feet of expansion for ingress and egress.
No. Where the parking is demolished in conjunction with the unit, or converted into it, the agency cannot require those off-street spaces to be replaced.
An ordinance must allow up to 1,200 square feet detached and up to half the existing primary dwelling attached, and it cannot set a maximum below 850 square feet of interior livable space, or 1,000 with more than one bedroom.
No more than 500 square feet of interior livable space contained entirely within a single-family residence, with its own entrance and an efficiency kitchen, and a deed restriction against selling it separately.
ADU builder by city
This work is requested through the home remodel page for your city, which names the local ordinance and the department that takes the application.
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