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Ken Lam Realty · Tools

A manufactured home on your own lot, or as an ADU?

Is it allowed in your city, what are the steps, and what does it cost all-in compared with building an ADU from scratch.

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sqft
sqft
Use it as
Home

Typical sizes: single-section 400–1,000 sqft, double-section 1,000–1,800 sqft. A detached ADU can be up to 1,200 sqft under state law.

Estimated all-in cost
$0
Stick-built ADU, same size: $0 · You'd save about $0 · Time:

Your steps

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Four things to know

The city has to allow itState law says a certified manufactured home on a permanent foundation must be allowed on any lot zoned for a single-family home. The city can only control the roof overhang, roofing and siding, and no tougher than for a regular house (Gov. Code §65852.3).
It can be your ADUState ADU law counts a manufactured home as an ADU (Gov. Code §66313). Same size limits and fee rules as any ADU: no city impact fees at 750 sqft or less.
The 10-year catchA city may refuse a home that is more than 10 years old at the time you apply for the permit. Used homes: ask the planning counter first, before you buy.
Foundation turns it into real estateOnce the home is on a permanent foundation, the building department records HCD form 433A and HCD cancels the vehicle-style title. From then on the home is part of the land, taxed and sold like a house. That's T174.
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Next steps

  2. Get 2 dealer quotes that list delivery, setup, foundation and permits line by line. "Base price" alone hides half the cost.
  3. Compare with a stick-built ADU and see rent and payback in T91.
  4. Financing a home on your own land? See which loans open up once it's on a foundation in T164, and insure it with T175.

Many people get this wrong: "A manufactured home is the cheap way to an ADU." The box is cheap. The site isn't. Foundation, sewer, power, crane and permits can run as much as the home itself on a tight San Jose lot. It still usually beats stick-built, just by less than the brochure says.