One thing you’ll definitely need is a plan that meets the local design and building codes. Los Angeles and many other cities offer preapproved ADU designs on their websites, but few people use them — according to the Los Angeles Department of Building and Safety, only about 20 applications have been submitted with one of the city’s standardized plans.
Builders say the preapproved plans are often costly to build, and every project requires some degree of customizing. “An ADU for the Joneses is not going to work for the Jacksons next door,” Acton said, noting that “every lot is different, setbacks are different, utility hookups are different, motivations are different, financing is different.”
Besides, he said, “if you’re going to be spending six figures on something, you’re going to want to make it your own. … How often do you go down and buy a car and say, ‘It just needs to have four wheels’?”
Nevertheless, the standardized plans are a good place to start because they give you an idea of what you can do with the space available and what you want in your unit.
To develop a plan of your own, you’ll need either an architect and a builder or a design-build contractor who can handle both jobs. (Some companies, such as Cottage and Housable, handle design and permitting, then connect you to a builder.) You’ll want to use a state-licensed contractor; the California Department of Consumer Affairs offers a number of tips for how to find the right one on its website.
Los Angeles officials advised hiring someone who knows and can navigate the city’s many requirements, including its environmentally conscious Green Code. Basically, the process involves having your plan approved, obtaining all the required permits and then having city inspectors sign off on the work — as it’s being done and after it’s finished.
But your plan may require revisions to win approval, and there may be multiple local agencies involved in reviewing your structure and utility hookups. In Los Angeles, for example, you’ll need approvals from the departments of Building and Safety, Planning, Sanitation, Engineering, and Water and Power. To help the uninitiated, the city offers a preliminary plan check service to answer questions about the requirements before a plan is submitted for approval.
Getting the L.A. Department of Water and Power to green-light a project can be particularly time-consuming, said Sean Phillips, Homestead’s co-founder and chief product officer. The DWP originally stopped any project that was within 15 feet of a power line, he said, which ruled out quite a few backyards in Los Angeles. Now the agency allows those projects, Phillips said, but it can still take three or more months for an inspector to come to the property and give the necessary approval.
Nevertheless, Isaac Schneider, Homestead’s co-founder and chief operating officer, insisted that the city “has one of the best permitting processes in the state.” He added, “Generally, L.A. city moves very quickly.” By contrast, Phillips said, projects in unincorporated Los Angeles County are taking six to eight months to obtain permits.
Lang said it’s important to get multiple bids for the work before picking someone. “It they get three bids, they’ll see the vast difference in bidding. It’s insane,” he said.
And once you’ve started building, you’ll need to protect yourself against your own urge to bust the budget. Lang said his customers will “want nicer stuff” as they see the project coming to fruition. “They’re like, ‘Oh my God, this is like a mini house.’ They get all excited, and they want to do more. … There’s just so many options that I think people become aware of through the process.”
In addition to the need for housing, one reason the state sought to make it easier to build ADUs was because of the safety hazard posed by the illegal units that were rampant across California, Lang said. In his view, the easiest building project to get approved these days is an ADU. The process of getting permits, he added, “seems more crazy than it really is.”