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REF_07 / CONSTRUCTION

Manufactured Home

Also known as: HUD-code home

A factory-built home certified to federal HUD code — different legal class from a modular or stick-built ADU.

DEFINITION

A manufactured home is built in a factory to the federal HUD code (24 CFR 3280) rather than to the IRC. Manufactured homes carry a different legal class than modular or stick-built dwellings: they're typically titled like a vehicle, not real property, and many cities (including Seattle) do not allow manufactured homes as ADUs on standard single-family lots. Modular homes — also factory-built but to the IRC with a Washington L&I label — are treated as conventional construction and are ADU-eligible.

FAQ

Frequently asked

  • What does Manufactured Home mean in the context of an ADU?

    Manufactured Home is part of the regulatory and technical vocabulary you encounter when permitting and building an accessory dwelling unit in Washington. Knowing the term matters because reviewers, inspectors, and your lender will use it without explanation. We define Manufactured Home in plain English and connect it to the specific code citation, fee, or construction detail that affects your project. Use the related-terms section to navigate adjacent concepts you'll need on the same plan set.

    Go deeper: Explore Attached ADU

  • Where does Manufactured Home apply in the WA ADU process?

    Manufactured Home typically shows up in either the design phase (when the architect or designer is laying out plans against zoning), the permit phase (when reviewers check the submittal against code), or the construction phase (when inspectors verify built conditions match the approved set). The same term can appear in your loan documents if it affects valuation or risk. Each glossary entry maps the term to the exact phase where it matters most.

    Go deeper: Read the Puget Sound ADU timeline guide: kickoff to keys guide

  • Why should I care about Manufactured Home for my project?

    Misunderstanding Manufactured Home is one of the most common reasons ADU projects hit avoidable cost overruns or permit delays. A clear shared vocabulary between you, your designer, and your builder shortens decision time and reduces change orders. Bookmark this glossary and refer back as you progress from feasibility through final inspection.

    Go deeper: Glossary: Manufactured Home

  • How does Manufactured Home affect my ADU budget?

    Most glossary terms map to either a cost line, a review timeline, or a permit fee. Where Manufactured Home drives cost, the impact is itemized in our standard fee schedule and itemized at feasibility — so by contract time, Manufactured Home is a known number, not a discovered surprise. Click through to the related cost or permit page for the current Manufactured Home-specific dollar range and timeline.

    Go deeper: Read the Five hidden ADU costs that wreck Puget Sound budgets guide

  • Is Manufactured Home regulated under RCW 36.70A.681?

    WA statewide ADU preemption (RCW 36.70A.681 / HB 1337) covers many ADU-adjacent topics: size caps, setbacks, owner-occupancy, parking, height, lot-size minimums. Whether Manufactured Home falls under preemption depends on its specific scope — design review, side-sewer permitting, drainage review, and tree-protection rules are generally NOT preempted, while size/setback/parking generally ARE. Each glossary entry flags the preemption status.

    Go deeper: Read: Bellevue ADU rules — what changed under HB 1337

TERM_MANUFACTURED HOME

Need "Manufactured Home" explained for YOUR lot? Get it in plain English.

Definitions help. Applying them to your specific property is what matters. Send the address and we'll explain how Manufactured Home plays out on your build.

  • Plain-English read of "Manufactured Home" on your lot
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