Building A-du: Prelude

Somewhere in Los Angeles right now, a homeowner is standing in their backyard with a tape measure and a hunch. Maybe the kids moved out and the house feels too big. Maybe a parent is getting older and a place to land nearby would change everything. Maybe the mortgage got heavier and that strip of yard behind the garage suddenly looks like it could be doing more than holding a couple of bikes and a dead lawnmower.

They've heard the three letters by now: ADU. An accessory dwelling unit, a second small home on the same lot. They've heard it's finally possible in a way it wasn't a few years ago. What nobody has told them, plainly, is what to actually do next. Who to call first. What it costs. How long it takes. Whether the thing they're picturing is even legal on their lot.

That gap, between "I think I could build something here" and "I have a permitted, finished, rented unit with a tenant who's happy to live there," is the thing I've spent the last few years building a company around. This series is the honest story of how.

I'm Chris Koss. I'm a California-licensed architect, and I run A-du.

When I moved to downtown LA from the Midwest, I didn't even know an ADU was an option, let alone what one was. I came to work for Perkins&Will's downtown office designing healthcare projects like hospitals, MOBs, and clinics, so I was seldom exposed to local residential design nuances and trends. It wasn't until 2020 that I discovered the then-relatively-new ADU typology, and the contrast struck me: I had come from a place where space is abundant to a city where virtually every lot is developed and single-family residential lots seem to dominate.

To me, LA has always felt like a collection of urban centers surrounded by a sea of single-family residences. This is no accident. LA was zoned for roughly 10 million people in 1960, then systematically downzoned through the 60s, 70s, and 80s (Prop U in 1986 being a major example) under pressure from homeowner groups. Today, Angelenos face a housing crisis like no other, the product of decades of restrictive zoning that intentionally limited population growth. Some multi-family developers do undertake the arduous process of rezoning single-family lots to add housing stock, but these efforts often fail or are accused of undermining the character of otherwise single-family neighborhoods.

ADUs are an unusual policy lever. They take the people who already live in a neighborhood, often people who have been there for decades, and make them participants in expanding the housing supply instead of bystanders or opponents of it. They densify thoughtfully. They activate underused lots. They keep families and caregivers and adult children near each other when the alternative is leaving. They let renters live in genuinely good neighborhoods at prices that aren't possible in a new tower. As an architect I care about the built environment, and I care about proximity. I care about people staying close to the cultural, food, and social infrastructure they came for. ADUs do both.

In 2016, amid the state's unfolding housing crisis, California further paved the way for homeowners to build accessory dwelling units on their own property. The initial ADU framework was passed in 1982, but the big shift came in 2016 and 2017, when major legislation (SB 1069, AB 2299, and AB 2406) imposed a legal floor on local ordinances and removed strict restrictions on parking, fees, and permitting. The result has been a massive increase in development. Each year since has brought new efforts to ease restrictions on owner-occupancy requirements, lot sizes, and HOA rules.

Given all the continuous, top-down regulatory support for ADUs in California, I was surprised to find very little bottom-up support for the individual homeowners who actually set out to build one. Getting from concept to certificate of occupancy remains a fragmented process, full of invisible pitfalls, obstacles, and delays that discourage first-time ADU builders. That homeowner in the backyard with the tape measure is mostly on their own.

That's the gap that inspired A-du. Whether someone is contemplating a detached ADU, working with unpermitted or permitted plans, hiring contractors, or looking to rent out a finished unit, A-du is meant to make the next step clearer, so the path forward feels less like guesswork and more like a place where someone has already thought hard about what you need next.

A-du has three components. A-du Rent is the rental marketplace. It's the part of the platform that takes a landlord from "I have a finished ADU" through verifying their identity, screening a tenant fairly, generating and signing the lease, adding any addendums, and collecting rent each month. It also has an outreach side: when the City of Los Angeles publishes a completed ADU permit, we surface it as a draft listing and mail the owner a postcard inviting them to take it over. A-du Build is the plan-and-vendor side. It's a marketplace for pre-approved standard ADU plans, both plans uploaded by vendors and plans we surface from municipal programs already published. It's also where you can request permitting for a plan and track the permit fees along the way. The architects, engineers, and contractors who actually do the design and construction work are people you hire directly, under your own contracts with them. A-du Manage is the connective tissue: a portal for tracking permitting progress, plus marketplaces for the property managers and service businesses (cleaning, handyman, moving, landscaping, and so on) that any working ADU eventually needs.

The point of this series is to walk through what it actually took to build each of those pieces. Not the marketing version. The honest version. The order we built things in. The places where we shipped something, learned the model didn't fit real people, and rebuilt it. The small judgment calls (a five-day window vs. a seven-day window; re-issuing a lease vs. issuing a separate addendum; a thirty-day portable screening profile vs. a one-shot per-listing screening) that look tiny in isolation and decide the whole feel of the product when they pile up. The careful work of seeding a marketplace before you drive demand to it, and the slower work of letting the actual humans on the other side claim the listings we built for them.

The architect's lens runs through the whole thing. Neighborhoods, proximity, the built environment. ADUs are local infrastructure, and the workflow that supports them has to stay local-feeling all the way down. A landlord on A-du shouldn't feel like they've been absorbed into a faceless national chain. A tenant shouldn't feel like a row in someone's spreadsheet. A vendor shouldn't feel like a commodity. Most of the work I'll describe in the posts that follow is, when you trace it back, about keeping that local, human texture intact while still making the workflow correct, fair, and able to survive at scale.

Here's the order. Each post is one piece of the story, in roughly the order we lived it.

1. Why every landlord on A-du proves who they are before they ever touch a tenant's private information, and what that one step is really protecting.
2. How we found the right way to screen tenants, the wrong turn we took first and openly admit to, and what it takes to treat an applicant like a person instead of a fee to collect.
3. What happens when a screening result doesn't pass, and how we make a rejection fair for the tenant on the receiving end of it, so no landlord has to become a legal expert to do right by someone.
4. How we close a deal. A lease that lives in your dashboard, signed by both people, with none of the print-sign-scan-email misery every renter has been through.
5. The months we spent realizing we'd been calling our own customers the wrong word, and why fixing it was worth the trouble.
6. How A-du reaches ADU owners we've never met, by mailing a real postcard to a real mailbox about a listing we've already built for them.
7. The pre-approved ADU plan your city may already have, that almost nobody finds, and how surfacing it can shave months and real money off a build.
8. How you tell a qualified builder from a confident stranger when you're about to hand someone a six-figure project on your own property.
9. The local cleaning crews, handymen, and landscapers every working ADU eventually needs, and how we put them on the map without pretending they signed up for something they didn't.
10. The Saturday night a landlord decides they don't want to be the one taking the maintenance call, and the marketplace of local property managers we built for that exact moment.

I'll publish them roughly twice a week. If you've used A-du as a landlord, tenant, or vendor and there's a question you wish I'd answer in the series, write me at admin@a-du.homes. I read all of it.

Onward.