San Jose ADU Costs

San Jose preapproved ADU costs: plan price vs full cost

A preapproved plan can help. But the plan price is not the price to build the whole ADU.

Published August 15, 2026

San Jose preapproved ADU plans can make the permit path faster. They can also make the first design step clearer.

But do not compare only plan prices. A plan is not a finished home. The full cost depends on your lot, utilities, foundation, permit work, construction, and finishes.

Quick answer

  • A preapproved plan is not a building permit.
  • A plan price is not the full ADU price.
  • Your lot still needs a site-specific plan.
  • Utilities and site work can change the cost a lot.
  • Ask for one written list of everything included and excluded.

Plan price, site price, and build price

Think about the cost in three buckets.

  1. Plan price. This is the drawing package.
  2. Site and permit work. This puts the ADU on your exact lot.
  3. Construction. This is the real build: foundation, utilities, framing, finishes, inspections, and cleanup.

If a price only covers bucket 1, do not compare it with a builder quote that covers all three buckets.

Current vendor cost signals

These are public cost signals from vendor pages and city-listed plan sizes. Confirm all prices before you buy because vendor pricing can change.

UniADU / Ca2Homes

City-listed plans: 499 sq. ft. 2 bed 1 bath; 747 sq. ft. 2 bed 2 bath.

Public price signal: UniADU public pages list 500 Fit at $4,000 and 750 Comfort at $5,000.

Watch this: These are plan prices, not construction prices. Ask who handles the builder and permit.

GetADU / J. Kretschmer Architect

City-listed plans: 748 sq. ft. 2 bed 1 bath; 476 sq. ft. 1 bed 1 bath.

Public price signal: GetADU says plan prices are on each design page and says past ADU builds have ranged from $232K to $402K.

Watch this: Ask what site planning costs, who gets contractor bids, and who stays involved during construction.

LiveLarge

City-listed plans: 795 sq. ft. 2 bed 2 bath.

Public price signal: LiveLarge public pages list the L-795 starting at $245,000 plus installation.

Watch this: Ask for the installed price, delivery needs, crane needs, utility scope, and site work.

What may still be missing

Ask if these items are included:

  • Site visit.
  • Survey or base map.
  • Site-specific plan.
  • Permit submittal and city comments.
  • City permit fees.
  • Foundation.
  • Utility trenches.
  • Sewer, water, gas, and electric work.
  • Electrical panel upgrade.
  • Delivery or crane access.
  • Appliances and finish items.
  • Landscape repair after construction.

How to compare quotes

Ask every vendor to write what is included and what is excluded. Then compare line by line.

If one company gives you plan price only, and another gives you a full build price, those numbers are not the same kind of number.

Use this next: what should be included in an ADU quote.

Also compare preapproved ADUs vs custom ADUs in San Jose before you choose a plan path.

Sources

Frequently asked questions

Are San Jose preapproved ADU plans free?
No. The city lists vendors. Homeowners contact the vendors to learn plan price, services, and installation approach.
Is the plan price the full ADU cost?
No. The plan price is only one part. You still need site planning, permits, city fees, utilities, foundation, construction, finishes, and inspections.
Can a preapproved ADU save money?
Sometimes. It can reduce design and review work if your lot fits the plan. But a hard lot can still add cost.
What should I ask before buying a preapproved plan?
Ask what is included, what is excluded, who prepares the site plan, who pulls the permit, and who builds the ADU.

Have a preapproved ADU quote?

Send the plan name and quote details. I will help you see what is included, what is missing, and what to ask next.

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