Buying Property in Marin or the North Bay? What to Check Before You Close
You found the house, the inspection came back fine, and you already have plans for it: an ADU out back, a converted garage, maybe a second unit. The problem is that most buyers find out what the property can legally support, and what was built without permits, after they close. By then it's their problem to fix.
I'm Sanem Surel. I spent years as a general contractor before I started PermitBox, and a lot of the permit problems I help people untangle started as a purchase nobody checked. Here's what I look at before a client commits to a property in Marin, Sonoma, or anywhere in the North Bay.
Why a home inspection isn't a permit check
A home inspector looks at condition: roof, foundation, electrical, plumbing. They're not checking whether the finished basement, the garage bedroom, or the back deck was ever permitted. That's not their job, and most reports say so in the fine print.
Seller disclosures help, but they only cover what the seller knows or is willing to say. If the previous owner bought the house with the work already done, they may not know either.
A permit check is a separate step. It compares what the city or county has on file against what's actually standing on the lot.
Step 1: Pull the permit history
Start by requesting the permit records for the address. In Marin and Sonoma, who you ask depends on where the property sits:
Unincorporated Marin (much of West Marin, parts of Kentfield, Greenbrae, Tam Valley) goes through the Marin County Community Development Agency.
Incorporated cities like San Rafael, Novato, Mill Valley, and Sausalito each have their own building department and records.
Unincorporated Sonoma County goes through Permit Sonoma. Cities like Santa Rosa and Petaluma keep their own.
Older files may be on paper or microfiche and can take a while to come back. Ask early in escrow, not the week before your contingencies expire.
When the records come back, walk the property with them. Count bedrooms, bathrooms, and structures. If the listing says four bedrooms and the permits support three, you've found something worth asking about.
Step 2: Check zoning and allowed use before you plan anything
This is the step buyers skip most often, and it's the one that changes what the property is worth to you.
Zoning tells you what you're allowed to build and how the property can be used. It sets setbacks, height limits, lot coverage, and whether a second unit is allowed. In the North Bay, a few other layers often apply on top:
Coastal zone rules in parts of West Marin and the Sonoma coast, which can add a separate review.
Septic systems in rural areas, which can limit how many bedrooms or units the site can support.
Wildfire and steep-slope areas, which can affect access, defensible space, and construction requirements.
Design review in some towns, even for projects that meet zoning.
State ADU law opened up a lot, but it doesn't erase site conditions. If you're buying with an ADU in mind, read how to get an ADU permit in Marin County before you assume the backyard will work.
What I've seen as a GC: the unpermitted work you inherit
The most common situation I run into is simple. Someone buys a house with a garage turned into a bedroom, a lower-level unit, or an addition that was never permitted. It looked finished, so nobody asked.
Once you own it, that work is yours. If you want to remodel, add an ADU, or refinance, it tends to come up. Legalizing it usually means documenting what's there, opening up walls or ceilings so an inspector can see framing, wiring, and plumbing, and bringing it up to current code. Sometimes it can't be legalized as built and has to be changed or removed.
From the construction side, what matters is how much of the work is hidden. An inspector can't sign off on what they can't see. That's why I try to catch these issues before closing, when you still have options: ask the seller to fix it, adjust your offer, or walk away. After closing, you only have the first two, and you pay for both.
The same goes for applications down the road. Missing or inaccurate existing-condition information is one of the permit mistakes that get applications rejected.
A short pre-purchase checklist
Before your contingencies run out:
Request the permit history for the address from the right agency.
Compare permitted work to what's on site: rooms, units, structures, decks, retaining walls.
Look up the zoning and any overlays (coastal, fire, slope, historic).
Confirm utilities: sewer or septic, water, and electrical capacity if you're adding space.
If you have a project in mind, check whether the site can actually support it.
That last step is what a feasibility report covers. If you want to see what's included, here's what goes into an ADU feasibility report.
Frequently asked questions
Can I check permit history myself before buying? Yes. Most Marin and Sonoma agencies take records requests online or by email. The harder part is reading the records against the property and knowing what's missing.
What happens if I buy a house with unpermitted work? You take on the responsibility. It may come up when you remodel, sell, or refinance. Legalizing it usually means opening up finishes for inspection and bringing the work to current code.
Does zoning allow an ADU on every lot in Marin? State law allows ADUs on most residential lots, but septic capacity, slope, fire access, coastal rules, and setbacks can still limit size, location, or cost. Check the site before you count on it.
How long does a pre-purchase permit check take? It depends on the agency and how old the records are. Start as early in escrow as you can.
Before you commit
If you're in escrow or about to make an offer in Marin or the North Bay, I can help you figure out what the property actually supports before you're locked in. Book a consulting call to talk it through, or request a feasibility report if you already have a project in mind.
