Building A-du: Part Seven

Let me start with the practical part, because if you're thinking about building an ADU, this is the post in the series that might actually save you money.

There's a good chance your city has already done some of the hardest, most expensive parts of your project for you, and is basically giving the result away. They're called pre-approved standard plans, and they're one of the best-kept accidental secrets in California housing. The problem is almost comically simple: nobody can find them.

This is the seventh post in my series on building A-du, the ADU platform I started. The last post was about the renting side, how we reach owners of finished ADUs. This one is the mirror image, the building side, for the homeowner standing at the very start, looking at the cost and the timeline and quietly wondering if this is even doable. It often is, and more affordably than they think, and here's why.

When you build an ADU the usual way, two of the scariest line items are design and permitting. You pay an architect to draw something. Then you wait, sometimes for months, while the city's plan check pores over it, sends it back, you revise, you resubmit. That back-and-forth is where budgets and timelines go to quietly bleed out.

A pre-approved plan skips most of that. Several California cities have published libraries of standard ADU designs that they've already vetted. LADBS, the building department for the City of Los Angeles, has a standard ADU plan program. The City of Riverside has one it calls DWELL. Others have their own. Each program is a set of complete plans, each one drawn by a real architecture or engineering firm, and each one represents a faster, cheaper, lower-risk path to a permit, because the city has already blessed the design. Pick one of these, and you've compressed the part of the project that scares people most.

So why doesn't everyone use them? Because finding them is miserable. They're scattered across city websites, buried on subpages that were clearly never built for browsing, sometimes a PDF inside a PDF. The homeowner who'd benefit most never stumbles onto them. And the architects whose work is sitting in those programs get no credit and no discovery from it; their good work just gathers dust on a municipal server.

I've felt both sides of this. As an architect, I know what it takes to get a plan through a city's pre-approval; it's real, serious work, and watching it vanish into an obscure city subpage is a quiet waste. And as someone who cares about ADUs actually getting built, I know that the homeowner who finds a pre-approved plan early is far, far more likely to cross the finish line, because the risk is lower, the design is settled, and the cost is more predictable. That's exactly the kind of friction that turns "someday, maybe" into "we're really doing this."

What A-du Build does about it

A-du Build's plan marketplace pulls from two places. The first is plans that architects and design-build firms list with us directly. The second is those municipal pre-approved programs. We go find them, and we surface every plan in one browsable place, each one clearly labeled with where it came from.

The pipeline works just like the postcard one from the last post. A scraper visits each program's published list of plans, at a polite pace, and brings the plans, the original city web address, and proper credit into A-du. A plan from LADBS shows up reading "Source: City of Los Angeles," with a link straight back to the original city page. We're not hiding where it came from. We're doing the opposite, making it findable and pointing right at the source.

Two pieces of this took real care:

Letting the real designer step forward. When the architect or firm that originally drew a pre-approved plan finds their work on A-du, they can claim it. If they sign in with the email address the city published for that plan, or confirm through a link we send to that address, the claim goes through. Otherwise they give us their license number, a portfolio link, and any supporting proof, and a person on our side reviews the claim before approving it. Once a claim is approved, the listing becomes theirs. From then on, homeowners interested in that plan reach them directly. The listing keeps the city's attribution, but the designer finally gets the credit and the visibility, which was the whole point.

An exit, built before anyone asked for one. If an architect or rights-holder ever wants a plan taken down, for any reason, there's a clean, simple path: they tell us who they are and why, we review it, and it comes down. We built that on day one, not the week we got our first complaint. The right moment to design the door marked "out" is before anyone needs it.

We also hold a plan for the right person. While a plan is still unclaimed, anyone interested can raise their hand, and we'll let them know the moment its designer claims it. The homeowner who finds a great plan first doesn't lose the thread just because it doesn't have an architect attached yet.

We started with LADBS and added Riverside's DWELL, and built it so that adding the next city is a small, repeatable job rather than a custom project each time. As of September 2026 the catalog also includes plans from San Diego County, four San Diego-area cities (Chula Vista, Escondido, Imperial Beach and San Marcos) and New York City's housing agency (HPD). We've written a scraper for Long Beach's program, but none of its plans are live on A-du Build yet. Since January 1, 2025, state law has required every California city and county to have a pre-approved ADU plan program. The goal is for A-du Build to carry all of them.

What it means for you

If you're a homeowner even idly considering an ADU, A-du Build now shows you the pre-approved plans from the city programs it carries, side by side with plans from private architects, in one catalog you can browse and filter. In concrete terms, that's a real shot at a shorter timeline, a more predictable cost, and a lot less permit anxiety, because a design the city has already approved is a design you don't have to sweat through plan check from scratch. That is the most tangible "here's what this saves you" in the whole series.

If you're a vendor, an architect, a design-build firm, an engineer, and one of your plans is in a city's pre-approved program, you can claim your listing and finally get found for that work. Uploading your own plans to A-du Build, pre-approved or not, is free. No listing fee, ever, on plan uploads. The leads from your listing come straight to you.

And if you hold the rights to a plan and would simply rather it not be listed, the way out exists, and we'll honor it.

What I keep coming back to

The lesson I keep relearning across this whole platform is that the right way to build a marketplace is to do the work for the people who'll eventually own it, instead of demanding they do it for you. We don't ask architects to dig up and re-upload their own pre-approved plans cold. We surface them, credit the city that approved them, and invite the original designer to step in and take the wheel. That's a far more respectful ask than "please come build our marketplace for us."

And there's a thread running through the last two posts that isn't an accident: the way we reach a finished-ADU owner by mail and the way we surface a city's plans for an architect are built the same. Find what's public, present it honestly with full credit, invite the right person to claim it, and hand them control. Keeping those flows shaped alike means a homeowner and an architect aren't forced to learn two completely different products. It's the same promise, kept the same way, on both sides of the build.

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Next time: the question every homeowner asks before they hand someone a six-figure project on their own property. How do I know this person is actually qualified, and not just good at sounding like it?