Permits Guide · San Francisco

Unpermitted Work in San Francisco: Risks and How to Legalize It

By Solid Bay Construction SF | Updated 2026

Unpermitted work is extremely common in San Francisco's older housing stock — a garage converted to living space decades ago, a kitchen moved without plans on file, an in-law unit built before ADU rules existed. It's rarely a crisis, but it's worth understanding the real risks and the path to fixing it.

Why It Matters

• Sale disclosure — California requires disclosure of known unpermitted work when you sell, and buyers' inspectors routinely catch square-footage or configuration mismatches against public records
• Insurance — a claim involving an unpermitted area (fire, water damage) can be denied or reduced if the work is found to be substandard or non-code
• Renovation trigger — pulling a permit for an unrelated renovation can surface old unpermitted work during DBI plan review, sometimes requiring it be addressed before your new permit is approved
• Resale value — unpermitted square footage typically isn't credited in an appraisal, understating your home's real value

How Legalization Works

San Francisco's DBI process for legalizing existing unpermitted work generally involves:

1. An assessment of what exists — often requiring opening up walls or ceilings to verify the electrical, plumbing, and structural work meets current code
2. Filing a permit application for "legalization of existing work" with as-built plans
3. Bringing any non-code elements up to current standard (this is usually where the real cost lives)
4. Passing inspection on the legalized scope

What It Typically Costs

Cost varies enormously depending on what's behind the walls. A straightforward legalization of a professionally-built but never-permitted addition might run $10,000–$25,000 in permit and correction costs. A garage conversion built without any inspection oversight can run significantly higher once wiring, plumbing, and structural issues are corrected to code.

A Practical Note

Many homeowners choose to legalize unpermitted work at the same time as an unrelated renovation, since walls are already open and an expeditor is already engaged with DBI — this is usually the most cost-effective time to address it, rather than as a standalone project later.