Tiny & Modular Homes in San Diego, CA

In most cases, yes.

• Modular homes on permanent foundations are appraised the same way as site-built homes
• Constrained supply and high rents support both rental income and resale value
• An ADU can generate meaningful ongoing income in a market with this rent level
• California law now allows ADUs to be sold separately as condominiums where the local jurisdiction has opted in, which can change the long-term calculation

Tiny homes on wheels behave differently: they are titled as RVs and tend to depreciate more like vehicles than real estate.

Yes, and for buyers who want acreage or a towable home it is often the more practical route. Areas worth considering:

• Unincorporated San Diego County
• The backcountry around Ramona, Julian and Alpine
• The desert toward Borrego Springs

Rules vary by parcel. In this region three things matter most before you buy land: water access, septic feasibility, and fire hazard severity zone designation, which affects both what you can build and whether you can insure it. Factory-built modular homes are certified by the California Department of Housing and Community Development and must meet state code, while the county controls placement, foundations and utility connections.

San Diego is one of the most expensive ADU markets in the country. Typical all-in figures:

• $375 to $600+ per sq ft turnkey, with most complete projects between $300,000 and $450,000
• 500 sq ft one-bedroom: around $300,000
• 1,000 sq ft two-bedroom: around $425,000
• 1,200 sq ft three-bedroom: around $450,000
• Basic site work on a level, accessible lot: about $35,000
• Separate electrical meter: $15,000 to $30,000 or more
• Permit fees: roughly $10 to $20 per sq ft

Smaller units cost more per square foot, because a kitchen, bathroom and design fees do not shrink with the footprint. A smaller prefabricated unit can save money against a comparable site-built ADU, though the gap narrows on larger or two-story designs.

Yes. The California baseline that San Diego must follow includes:

• Detached ADUs of at least 850 sq ft for a studio or one bedroom, 1,000 sq ft for multi-bedroom
• 16 ft height, rising to 18 ft near a major transit stop
• Side and rear setbacks as small as 4 ft
• No owner-occupancy requirement
• No impact fees on ADUs of 750 sq ft or less

San Diego also runs a Bonus ADU Program, allowing an additional market-rate ADU for each deed-restricted affordable unit, concentrated in Sustainable Development Areas. It was significantly narrowed in August 2025:

• Eliminated in eight single-family zones, with limited high-opportunity exceptions
• Parking now required outside transit priority areas
• Fire sprinklers required on all affordable and bonus units
• Unit counts capped by lot size at four, five or six

Confirm your zone and eligibility with the City of San Diego before designing around the bonus program.

It depends on how the home is built.

• On a permanent foundation, a tiny home is treated as an accessory dwelling unit and is broadly permitted, because California law requires cities to allow ADUs in residential zones
• A tiny home on wheels is titled as an RV and generally cannot be a permanent residence on a residential lot
• San Diego applies fire-safety limits: ADUs are restricted in high and very high fire hazard severity zones, and properties generally need two evacuation routes
• Backcountry San Diego County offers more flexibility for towable homes, subject to county rules

ModelTown can help you compare homes that fit realistic San Diego placement scenarios.