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.
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.