Methodology

Most ADU content on the web is paraphrased state law under a fresh-looking date stamp. As of August 2026, the #1 search result for Tacoma’s ADU parking requirement — a page stamped “Updated June 2026” — still tells homeowners to build a parking space Tacoma stopped requiring in 2019. We built this site to be the opposite of that.

The pipeline

1. Primary sources only for facts. Every rule is read from the city’s codified municipal code or, where code hosts lag, the adopted ordinance text itself. Secondary sources are used to locate code sections, never to state facts.
2. Per-fact citations. Every cell on every page names the code section it comes from — down to the footnote where the footnote is what governs. If we can’t cite it, we mark it unverified or leave it out.
3. Adversarial re-verification. Before publication, load-bearing claims are handed to an independent fact-check pass briefed to refute them against primary sources. Our launch pass confirmed six of eight sampled claims and corrected two — both corrections are in the changelog, because a verification process that never finds its own errors isn’t one.
4. Ambiguity is published, not resolved by vibes. Where a city’s code genuinely conflicts with itself (see Everett’s DADU height), we publish the conflict, the competing readings, and what to ask the city — rather than picking the convenient answer.
5. Local history over state boilerplate. “Per HB 1337” is not a citation. Cities like Tacoma, Seattle, and Olympia liberalized years before the state mandate; attributing their rules to the 2023 statute misdates the rules and misleads about what changed. We date every rule to its adopting ordinance.
6. A public changelog. Every verification pass, ordinance caught, and correction is logged with a date. A date stamp you can’t audit is marketing; a changelog is a record.

The watchlist

Cities keep amending — Renton amended twice in 2025, Redmond’s June 2026 ordinance is pending codification, Everett is mid-housekeeping. Each city page lists its pending items, and we re-check them on every pass.

What this is not

Not legal advice, and not a substitute for your city’s planning counter — lot-specific overlays (critical areas, historic districts, shoreline) can change the answer for your parcel. It is, we believe, the most carefully cited starting point available.