Site Assessment in San Francisco, CA
A site assessment is the first real step in any ADU project: a physical walkthrough of your San Francisco property to check setbacks, grade, utility access, and soil conditions before a single drawing gets made. Most assessments in San Francisco run between $450 and $1,200 depending on lot complexity, and Benson ADU San Francisco includes the full written report with your ADU Design & Permitting package. Call (424) 328-5746 and we’ll get boots on your lot this week.
We treat site assessment as the make-or-break moment for your budget. A sloped Sunset District lot drains differently than a flat Noe Valley parcel, and a garage conversion on a 25-foot-wide Richmond District lot faces different setback rules (setbacks are the required distances between your building and the property line) than a detached backyard unit in the Excelsior. Getting this wrong on paper means expensive redesigns later. Getting it right up front means your permit package moves through the San Francisco Planning Department without a stop-work surprise.
When You Need Site Assessment
Most homeowners in San Francisco call us for a site assessment in one of these situations:
- You’re considering an ADU but don’t know if your lot can support one. A 2,500-square-foot Bernal Heights lot has different constraints than a 5,000-square-foot Sunset parcel. We’ll tell you what’s actually buildable, not what’s theoretically possible.
- You have a sloped or irregular lot. San Francisco hills create drainage, retaining-wall, and foundation challenges that flat-lot guides never mention. If your backyard drops six feet from the house, that’s a real number that affects your foundation plan and your budget.
- You want to convert a garage or add a JADU. A JADU (junior accessory dwelling unit) converts existing space inside your home’s footprint. The assessment confirms whether your garage’s ceiling height, egress, and utility connections actually meet San Francisco code before you invest in drawings.
- You’re comparing prefab versus site-built. A factory-built unit from Boxabl, Plant Prefab, or Abodu needs crane access and a specific foundation type. We check your street width, overhead wires, and soil bearing capacity so you know which brands are actually viable on your specific San Francisco lot.
- You got a verbal quote from another contractor and want real numbers. We walk the same ground, take the same measurements, and hand you a written price before work starts. No “we’ll figure it out during construction.”
- You’re buying a house and want to know ADU feasibility before you close. We assess the lot as-is and tell you, in writing, whether the ADU you’re imagining is realistic on that specific property.
Our Site Assessment Process
Here’s exactly how a Benson ADU San Francisco site assessment works, step by step:
- Phone consultation and records review. You call (424) 328-5746, we talk through your property and goals, and we pull public records on your parcel: lot dimensions, zoning district, any existing permits or violations. We look for red flags before we ever step on site.
- Physical walkthrough. A uniformed, background-checked technician walks your entire property with you. We measure the lot, check access points, locate utility connections, and note the slope, soil type, tree locations, and neighboring structures that could impact your ADU.
- Setback, zoning, and code check. We verify your rear, side, and front setbacks against San Francisco’s current ADU ordinances. If you want a detached unit in the rear yard, we confirm the structure will clear the required distances and meet height limits.
- Utility and drainage evaluation. We identify where your water, sewer, electrical, and gas lines run, and whether connecting a new ADU means trenching across your yard or tying into existing lines at the house. Poor drainage on a sloped Glen Park lot can add serious foundation costs, so we flag it now, not later.
- Brand feasibility review. Based on access, soil, and lot geometry, we tell you which prefab brands work on your property. A narrow Miraloma Park street may rule out crane delivery for a Dvele or Boxabl unit, while a wide Marina District street may not. You get a clear yes/no on each option.
- Written report and price. Within a few business days, you receive a written site assessment report with findings, constraints, recommendations, and a written price for the design and permitting work ahead. That price is locked. No surprises at the door.
Site Assessment Pricing in San Francisco
A site assessment in San Francisco typically costs between $450 and $1,200. Here’s the breakdown:
| Assessment Component | Typical Cost Range |
|---|---|
| Standard flat-lot walkthrough and report | $450 – $650 |
| Sloped or irregular lot assessment | $650 – $900 |
| Full ADU feasibility study with utility mapping | $850 – $1,200 |
| Prefab brand viability check (crane access, foundation type) | $150 – $300 add-on |
What affects the price? The size and slope of your lot, how many ADU types you’re weighing (detached, attached, garage conversion, JADU), whether we need to map utility lines, and whether your property has known drainage or soil issues. If your lot has a steep grade, poor access, or dense tree coverage, the assessment takes longer and costs more.
Here’s what matters: when you hire Benson ADU San Francisco for the full ADU Design & Permitting scope, the site assessment fee rolls into your project total. You’re not paying extra for it; you’re paying for certainty.
Free estimate: The initial phone consultation and records review is always free. Call (424) 328-5746 and tell us about your property. We’ll tell you what we can see from the records before we even schedule the walkthrough.
Why Our Assessment Beats a Free Estimate
Plenty of San Francisco contractors offer a “free estimate” that’s really a 20-minute walkthrough and a verbal number. A real site assessment is different. We’re measuring, checking code, mapping utilities, and giving you a written report you can hold. That’s the difference between a guess and a plan, and it’s why our assessment stands behind every design and permit package we produce.
FAQs – Site Assessment
Do I need a site assessment before I can get ADU plans drawn?
Yes, in practice. San Francisco ADU designs depend on your lot’s actual dimensions, setbacks, and utility locations, and a drawing made without a site assessment is a guess with a stamp on it. We assess every property before we start design work, because it’s the only way to give you a written price and a permit package that won’t stall.
Can you do a site assessment on a lot I don’t own yet?
Yes, with the seller’s permission. If you’re under contract on a San Francisco home and want to know if an ADU is feasible before you close, we can walk the property during your inspection period and deliver a written feasibility report in a few business days. Call (424) 328-5746 to schedule it.
How long does a San Francisco site assessment take?
The on-site walkthrough usually takes one to two hours depending on lot size and complexity. The written report follows within three to five business days. If you’re under contract on a property and working against an inspection contingency, we can prioritize a 48-hour turnaround. Call us and explain your timeline; we’ll tell you what’s possible.
Will you give me the assessment report even if I don’t hire you for the ADU?
Yes. The report is yours. If you take it to another contractor, that’s fine; you paid for the information. We’re confident enough in our written price and process that we don’t hold reports hostage. But if you decide to move forward with Benson ADU San Francisco, the assessment fee rolls into your project total.
What if my site assessment finds a problem that kills the ADU?
Better to find out now than after you’ve spent $15,000 on drawings and permits. If your lot can’t support the ADU you want due to access, grade, or code constraints, we tell you in writing and show you what options remain. Sometimes it’s a different unit type; sometimes it’s a different placement. The assessment is how you avoid expensive surprises.
Is it cheaper to repair or replace?
For a site assessment, this usually comes up when homeowners are weighing a foundation or retaining wall issue against building an ADU around it. Most of the time, addressing the issue before design is cheaper than retrofitting around it later. Call (424) 328-5746 with your property details and we’ll walk you through the trade-offs in plain English.
Site Assessment and Prefab Brand Fit
San Francisco’s hills, narrow streets, and dense lots make prefab brand selection a real decision, not a marketing bullet. Here’s what we check when we walk your property:
- Crane access. A full modular unit from Boxabl or Plant Prefab arrives on a flatbed and typically needs crane placement. If your street is too narrow for a crane or overhead Muni lines block the lift, we flag it during the walkthrough and explore panelized alternatives.
- Foundation type. A steep slope may require a pier-and-beam foundation, which affects which prefab systems will work. James Hardie cladding and Tuff Shed structures each have specific mounting requirements we verify against your lot’s soil and grade.
The point is simple: we don’t sell one product. We show you which brands fit your specific San Francisco lot and which don’t, backed by measurements, not preferences.
Why San Francisco Homeowners Choose Benson ADU San Francisco
We’re part of the Relay Home Co. family, founded in 2006, and every project we touch operates under the same standards: a written price before work starts, a 365-Day Done Right Promise, and a written guarantee on every project. If covered work isn’t right within a full year, we make it right. That’s not a slogan; it’s stamped on every contract.
Every technician who walks your San Francisco property is background-checked and in uniform. You always know who’s on your lot and when they’ll arrive. You get a live person on the phone whenever you call, day or night. And you get the written report, the written price, and the honesty to tell you when an ADU doesn’t make sense on your lot.
Ready to Get Your San Francisco Lot Assessed?
If you’re considering an ADU, a garage conversion, or a backyard unit anywhere in San Francisco, start with the one step that answers every other question: a professional site assessment from Benson ADU San Francisco. Call (424) 328-5746 for a free phone consultation and records review. We’ll tell you what we can see from the public records, schedule your walkthrough, and hand you a written report you can actually build on. Written price before work starts. Guaranteed in writing for 365 days. That’s how we work.
Written by Troy Eastman, Owner at Benson ADU San Francisco, serving San Francisco.
