Site Assessment in San Francisco, CA
A site assessment for an ADU in San Francisco typically costs $500 to $1,500 when done as a standalone service, and it’s the single most important step before committing to a design, a builder, or a financing plan. It answers three questions that determine everything downstream: Can you legally build an ADU on this specific lot? What physical constraints will shape the build? And what will it actually cost to get from where you are now to a permitted, buildable plan?
At Lodgewick ADU San Francisco, we’ve been doing these assessments since 2010 as part of the Kingswell family of home-service companies. Russ Delmar leads our San Francisco team, and he’s walked hundreds of lots across the city, from the flat grids of the Sunset and Richmond to the steep, fog-belted slopes of Glen Park, Noe Valley, and Twin Peaks. Each neighborhood brings its own soil, slope, setback, and sewer realities, and those realities show up in the price of your ADU long before a single nail is driven. That’s why we put the assessment first. A thorough site assessment is the difference between a design that gets permitted in months and one that stalls for a year.
This page covers what a site assessment includes, when you need one, what it costs in San Francisco, and how our process works. If you’re ready to talk about your specific lot, call us at (707) 760-0502 and a live person will answer, any hour, any day. We’ll give you a straight answer and a written price before any work starts.
If you’re earlier in the process and want to understand how this fits into the bigger picture, start with our full ADU Design & Permitting overview, then come back here when you’re ready to dig into your property.
Key Takeaways
- A site assessment tells you whether your San Francisco lot can legally and physically support an ADU, what it will cost to build, and what design constraints you’re working with before you spend money on drawings.
- Standalone site assessments in San Francisco typically run $500 to $1,500, and we absorb that cost into the design contract when you move forward with Lodgewick.
- San Francisco-specific factors like slope, soil type, sewer lateral condition, and Planning Code setbacks can swing your ADU budget by tens of thousands of dollars. You want to know about these before you commit.
- Our assessment ends with a written report and a written price for the next phase. No surprises, no vague promises.
- Call (707) 760-0502 for a free phone consultation and a firm quote on your site assessment.
When You Need Site Assessment
Not every homeowner needs a formal site assessment on day one. But most people who skip it end up paying for the omission later, either in redesign fees, permit rejections, or change orders mid-build. Here are the situations where we tell San Francisco homeowners, plainly, that an assessment is the right call:
- You’re considering a detached ADU in a rear yard. San Francisco lots are famously tight. Rear-yard setbacks, existing structures, and access for equipment all constrain what can physically fit. In neighborhoods like the Outer Sunset or the Excelsior, we regularly see lots where a detached ADU is legal but the buildable envelope is far smaller than the homeowner assumed from looking at a satellite map.
- Your garage slopes, floods, or shows foundation cracks. Garage conversions are the most common ADU type in San Francisco, but a garage that was never meant to be living space often has slab or drainage issues. We’ve assessed garages in the Richmond District where the slab wasn’t poured with a vapor barrier, meaning any conversion needs to address moisture from below before framing can start.
- Your sewer lateral is old or you’re not sure where it runs. In much of San Francisco, the sewer lateral serving the main house is the same line an ADU would tie into. If your lateral is original clay pipe from the 1920s or 1930s, connecting a second dwelling may trigger a mandatory replacement. That’s a real cost that shows up in an assessment, but rarely in a generic online ADU calculator.
- Your lot has significant slope or sits in a slide zone. The eastern slopes of the city, around Bernal Heights, Potrero Hill, and parts of the Mission, are notorious for fill soil and creep. A foundation on those conditions costs more, and sometimes requires geotechnical input before a structural engineer will even look at the drawings. A site assessment flags this on day one.
- You’ve gotten wide-ranging quotes and can’t tell which one is real. If one builder says your ADU will cost $250,000 and another says $450,000, the gap usually comes down to site conditions each did or didn’t account for. An independent assessment gives you a factual baseline to compare bids against.
- You’re buying a property with ADU potential. If you’re considering a San Francisco home specifically because you want to add an ADU later, an assessment before you close can save you from buying a property that won’t pencil out. We’ve had clients walk away from deals in the Sunset because a sewer lateral replacement and slope remediation would have added six figures to the project.
Our Site Assessment Process
We follow a repeatable process, and we put the results in writing. You’ll know what we found, what it means, and what the next step costs, in plain English.
- Initial phone consultation. You call (707) 760-0502 and talk to a live person, not a voicemail. We ask about your property, your goals for the ADU, and any documents you already have, like a recent survey, title report, or old plans. This call is free, and it’s where we tell you if a formal assessment is worth your money at all. If it’s not, we’ll say so.
- Document review. Before we set foot on your property, we pull what’s available from the San Francisco Planning Department and the Department of Building Inspection. That includes your property’s zoning district, any historic or overlay designations, recorded easements, and permit history on the existing house. If your home is in a neighborhood like the Inner Sunset or Noe Valley with specific planning overlays, those come up here, not at the permit counter.
- On-site walkthrough. One of our uniformed, background-checked assessors walks the lot with you. We’re looking at slope, drainage, access, utility connection points, tree locations, and the condition of any structure you want to convert. We measure the buildable area, photograph everything, and note conditions that will affect foundation, framing, or mechanical systems.
- Utility and lateral check. We locate your sewer lateral where possible, assess your electrical panel capacity, and note gas and water service locations. In San Francisco, where many homes still have overhead service drops and 100-amp panels, the electrical picture alone can change an ADU budget by $8,000 to $15,000.
- Findings and recommendation report. Within about a week of the walkthrough, you get a written report. It includes what you can build on your lot, what constraints exist, what we recommend as the most cost-effective ADU type for your specific conditions, and a realistic budget range for the build. It also includes our written price for the next phase, whether that’s schematic design, full design and permitting, or a deeper geotechnical review.
- Sitting down to plan next steps. We walk you through the report on a call or in person. You ask questions. We answer them. If you want to move forward with Lodgewick for design and permitting, the cost of your site assessment is applied to that contract. If you want to take the report to another builder, that’s your report to keep.
We work with leading prefab ADU brands and materials regularly, and the assessment is where we figure out which one actually fits your lot. A Boxabl unit, for example, has different access and foundation requirements than a panelized build from Plant Prefab. If your lot has tight side access in the Richmond or the Mission, a prefab approach might not pencil out at all, and we’ll tell you that honestly before you get attached to a particular brand or rendering.
Site Assessment Pricing in San Francisco
Here’s the straight answer: a standalone site assessment from Lodgewick ADU San Francisco typically costs between $500 and $1,500, depending on lot complexity, how much document research is involved, and whether we need to bring in a geotechnical engineer or surveyor for anything beyond a basic walkthrough. If you move forward with us for design and permitting, that assessment cost is credited toward your contract.
| Assessment Component | Typical Cost Range in San Francisco | What It Covers |
|---|---|---|
| Basic lot assessment (flat lot, standard setbacks, documented utilities) | $500 – $750 | Document review, on-site walkthrough, utility panel check, written report, 30-minute follow-up call |
| Complex lot assessment (slope, slide zone, possible sewer lateral issues, access constraints) | $750 – $1,200 | Everything in the basic tier plus deeper Planning Code review, slope and drainage evaluation, more detailed utility mapping |
| Full due-diligence package (assessment plus surveyor verification or geotechnical referral) | $1,200 – $1,500 | Everything above plus coordination with a licensed surveyor or geotechnical engineer, with written findings folded into the report |
What actually drives cost on a San Francisco assessment is not square footage. It’s the unknowns. A flat rectangular lot in the Sunset with a recent sewer lateral and a 200-amp panel is quick to assess. A steep lot in Glen Park with a 1920s retaining wall, an old clay lateral, and a garage that’s partially below grade takes longer and demands more care. We’ll tell you upfront which category your property falls into, and you’ll have a written price before we schedule the walkthrough. That’s the Kingswell Guarantee in practice: written price first, real arrival window, clean job site, written guarantee on every job.
If you’re comparing us to other San Francisco contractors, ask them one question: “Will you put the assessment scope and the price in writing before you come out?” If the answer is vague, you have your answer about how the rest of the job will go.
What Happens After the Assessment
An assessment is only as useful as what you do with it. Here’s what the path looks like once you have our report in hand.
If your lot is clear and you’re ready to move, the next step is ADU Design & Permitting in San Francisco, where we take the findings from your assessment and turn them into permit-ready drawings, handle the Planning Department and Department of Building Inspection submittals, and manage the review process until you have an approved permit set. The assessment is the foundation; the design phase is where we start making concrete decisions about layout, materials, and systems.
If your lot has constraints, the assessment report tells you exactly which ones matter and what they’ll cost to address. Maybe it’s a sewer lateral replacement. Maybe it’s a retaining wall that needs an engineer’s stamp. Maybe it’s a slope stabilization requirement that changes where the ADU can sit. You’ll know all of this before you pay for drawings, which is the entire point.
And if your lot simply won’t support an ADU, we’ll tell you that too. That’s not the news anyone wants, but it’s better than spending $30,000 on plans that can’t get permitted. Russ has delivered that message more than once, and he’s never charged a client for pretending otherwise.
Why San Francisco Lots Are Different
San Francisco is not like the suburbs. The lots are small, the codes are layered, and the ground itself can be unpredictable.
Most San Francisco residential lots are 25 feet wide. Some, in the older grids of the Mission and the Western Addition, are even narrower. A 25-foot-wide lot with a 4-foot side setback on each side leaves a 17-foot-wide buildable strip for a detached ADU. That’s workable, but it demands precision. A design that fits a 30-foot-wide lot in Daly City may not fit your Richmond District property at all.
Then there’s the slope. The hills that make San Francisco beautiful also make it expensive to build on. Soil creep is real in many eastern neighborhoods, and the city’s geotechnical hazard zones overlap with some of the most desirable ADU territory in the city. We’ve assessed lots in Noe Valley where the difference between buildable and not came down to a geotechnical report that cost a few thousand dollars but saved the homeowner from a foundation design that would have been structurally marginal.
Sewer laterals deserve their own paragraph. The city has been under pressure for years to replace aging private laterals, and many San Francisco homes still run on the original clay pipe. When you add an ADU, the Department of Building Inspection often requires verification that the lateral is in condition to handle the added load. If it’s not, replacement is on you, and in San Francisco that can run anywhere from $8,000 to $25,000 depending on depth, street conditions, and how much of the lateral is on your property versus under the sidewalk and street. This is exactly the kind of cost a thorough assessment surfaces early.
We also look at tree protection. San Francisco has strict rules about significant trees, and if the best place for your ADU is under or near a protected tree, that changes the design envelope. The city’s tree ordinances are not optional, and they’re not something you want to discover during the permit review.
How Lodgewick Approaches Your Assessment
The Kingswell family has been building small houses on larger properties since 2010, and the name itself points to what we do. A lodge is a small house on a larger property, which is exactly what an ADU is. That’s not just a naming quirk; it’s the whole focus of the company.
When Russ Delmar walks your San Francisco lot, he’s looking at it through 14 years of specifically ADU-shaped experience. He’s seen the garage conversion that looked simple but hid a slab without rebar. He’s seen the backyard that looked flat but drained toward the house. He’s seen the electrical panel that looked modern but was maxed out with no room for a second dwelling. None of these show up in a Google Maps view. All of them show up in a careful site assessment.
We’re hands-on with the major prefab and panelized systems, and that matters for your assessment. James Hardie siding performs differently in the fog belt of the Sunset than it does on a sunny Noe Valley slope; Tuff Shed structures have specific foundation and anchoring requirements that work on some San Francisco lots and not others. When we recommend a material or a system, it’s because we’ve seen it perform in conditions like yours, not because it’s in a catalog.
Every Lodgewick assessment ends the same way: written findings, written price for the next step, and a written guarantee on the work we’ve done. That’s the 365-Day Done Right Promise, and it applies to the assessment itself. If we miss something in our assessment that should have been caught, and that miss causes a problem in the next phase, we make it right. You’ll have that in writing before we ever set up a ladder on your property.
FAQs – Site Assessment
How much does a site assessment cost in San Francisco?
A site assessment in San Francisco typically costs $500 to $1,500 depending on lot complexity, slope, utility unknowns, and whether geotechnical or surveyor input is needed. Basic flat-lot assessments run $500 to $750, while complex lots with slide-zone or access issues run up to $1,500. If you move forward with Lodgewick for design and permitting, the assessment cost is applied toward that contract. Call (707) 760-0502 for a written quote on your specific property.
How long does a site assessment take?
The on-site walkthrough takes 90 minutes to two hours, and the full written report is typically in your hands within five to seven business days. Document review with the San Francisco Planning Department and DBI is the part that varies, since some permit histories pull fast and others require a records request. We’ll give you a specific timeline when you call (707) 760-0502.
Do I need a site assessment if I’m only converting my garage?
Yes, and in San Francisco garage conversions deserve an assessment even more than detached builds in some cases. A garage slab poured decades ago may lack a vapor barrier, have no rebar, or sit below grade where drainage is a problem. Garages built on fill or at the base of a slope bring their own foundation questions. A two-hour assessment can save you from a $20,000 surprise mid-conversion. Call (707) 760-0502 and we’ll tell you whether your garage is a straightforward conversion or one that needs more attention.
Will the city require a survey as part of my ADU permit?
San Francisco generally requires a current survey for detached ADU permits, and occasionally for garage conversions if the property lines are unclear or the existing structure is close to a setback. We’ll tell you during the assessment whether your project needs one, and we’ll coordinate it as part of the design phase if you work with Lodgewick. A survey typically adds $1,500 to $3,000 to the project, but it prevents the far more expensive mistake of building a foundation that encroaches on a property line.
What if the assessment finds problems with my lot? Is the assessment wasted?
No. An assessment that finds constraints is the most valuable kind. Every constraint we identify, from a failing sewer lateral to a maxed-out electrical panel to a slide-zone designation, is a cost and a timeline risk that will come up eventually. Better to know before you pay for drawings than to discover it during a permit review or, worse, during excavation. The assessment gives you a factual basis to plan around those constraints, and if a constraint makes your project unfeasible, knowing now saves you tens of thousands. Call (707) 760-0502 if you want to talk through what we typically find on lots like yours.
Get Your Site Assessment Scheduled
If you’ve read this far, you’re likely serious about building an ADU on your San Francisco property. That’s the right instinct, and the right first step is knowing exactly what you’re working with.
Call Lodgewick ADU San Francisco at (707) 760-0502. A live person answers, 24 hours a day, seven days a week. No voicemail loops, no chatbots. You’ll talk through your property with someone who knows San Francisco ADU code, and you’ll get a written price for your site assessment before we ever step onto your lot. If the assessment turns into a design and permitting contract, the assessment cost is credited back.
We’ll show up when we say we will, in a real arrival window. We’ll leave your property cleaner than we found it. And every commitment, from the assessment findings to the work that follows, goes in writing under the 365-Day Done Right Promise. If it’s not done right, we come back and make it right. That’s how the Kingswell family has built since 2010, and that’s how we’ll approach your San Francisco ADU.
Written by Russ Delmar, Owner at Lodgewick ADU San Francisco, serving San Francisco.
