Homeowner Guides

The ADU Gold Rush: What Building One in L.A. Actually Takes

Build Hero Team · 07/03/2026 - 09:00

Los Angeles is in the middle of the largest backyard building boom in its history. Accessory dwelling units — granny flats, garage conversions, backyard cottages — now account for roughly one in five new homes permitted in the city. State law cleared the path; rent did the persuading. What stands between you and a finished unit is execution, and execution is where budgets go to be tested. Start by naming which project you are actually doing, because "ADU" covers three different animals. A garage conversion is the gentlest: structure, slab, and roof already exist, and the work is waterproofing, insulation, systems, and finishes — typically low six figures. An attached ADU shares a wall and often some plumbing runs with the main house, trading privacy for efficiency. A detached new build is ground-up construction — foundation, framing, utilities trenched across the yard — and it is priced like what it is: a small house, commonly reaching the mid six figures by the time it is truly done. The line items that surprise people are rarely the walls. They are the connections. Sewer depth and distance decide whether you gravity-drain or buy a pump. An aging main panel may need an upgrade before the new unit can draw a single amp — and utility timelines answer to no one's construction schedule. On hillside lots, soils reports and retaining conditions can reshape the budget before a shovel lands. None of these are exotic; all of them are knowable up front, if someone looks. The city has genuinely tried to help. Pre-approved standard plans can shave months off design review, and state law caps many of the old discretionary delays. But "streamlined" is a relative term. Between plan check, utility coordination, and inspections, a realistic calendar runs several months for a conversion and the better part of a year for a detached build — before you add the time it takes to choose a contractor well. Choosing well is most of the game. ADUs sit in an awkward middle: too big for a handyman, too small for firms chasing full-gut remodels, and perfectly sized for a crew that builds them on repeat. You want the bidder who asks about your sewer line before your countertops. The math still works — as a rental in a city that badly needs the units, as space for family, as the value of a second address on one deed. But it works best for owners who defined the project before pricing it: a measured site, a decided scope, and a contingency line that survives contact with the soils report. Build Hero was built to front-load exactly that definition, so the bids you collect describe the same building — and the one you accept gets built.