Sunny Drafting & Design
More than 60 percent of first-time ADU permit applications in Bay Area cities stall at plan check — and an incomplete or inaccurate site plan is the number one reason. Understanding the site plan requirements for ADU permits in the Bay Area before you submit can be the difference between a fast approval and months of costly revisions. Cities like San Jose, Oakland, and San Francisco each layer their own requirements on top of California state standards. Whether you're building a detached cottage or converting a garage, the site plan is where your permit lives or dies. If you want professional help from day one, our ADU and JADU design services cover site plans for every major Bay Area city.
California ADU law — codified under California Government Code Section 65852.2 — sets a statewide baseline. But local jurisdictions still control exactly how you document your project on paper. Your site plan has to satisfy both layers simultaneously. Miss either one and you're looking at a correction letter and weeks of delay.
This guide breaks down what cities want to see on your site plan, where Bay Area jurisdictions diverge from each other, and how to prepare a submittal that passes first review.
Contents
- What Goes on an ADU Site Plan: The Basics and the Details
- Site Plan Requirements by Bay Area City: A Side-by-Side Look
- What Actually Gets Projects Rejected at Plan Check
- Keeping Your Site Plan Accurate Through Permit Revisions
- Practical Tips for a Site Plan That Passes First Review
- Planning Your Site Plan for Long-Term ADU Flexibility
- Myths About ADU Site Plans That Are Costing Homeowners Time
- Frequently Asked Questions
- Next Steps
What Goes on an ADU Site Plan: The Basics and the Details
A site plan is a bird's-eye view of your entire property. It shows where every structure sits, how far each structure is from the property lines, and exactly how your proposed ADU fits into the overall picture. Every other sheet in your permit set references back to it — which means errors here cascade through the entire submittal.
Required Elements Every City Wants
No matter which Bay Area city you're in, your site plan needs these core elements:
- Property boundaries with exact dimensions — lot size, shape, and orientation based on a recorded parcel map
- All existing and proposed structures with labeled footprints
- Setback dimensions from the ADU to every property line (all four sides)
- Driveway, parking spaces, and pedestrian pathways
- Utility connections — gas, water, sewer, and electrical point of entry
- Easements and recorded encumbrances affecting the lot
- North arrow and graphic scale bar
- Legal description and assessor's parcel number (APN)
- Lot coverage calculation table showing existing and proposed totals
For a closer look at how setback requirements appear on a California site plan, that guide covers notation standards and the dimension errors reviewers flag most often.
Advanced Elements That Vary by City
Beyond the core checklist, many Bay Area cities require additional detail on the site plan itself:
- Topographic contours — typically required when lot slope exceeds 10–15 percent
- Stormwater drainage direction arrows and outfall location
- Tree canopy drip lines for any protected trees within 50 feet of construction
- Fire access path dimensions and turning radii (especially in hillside zones)
- Solar setback envelope notes (Palo Alto and some Santa Clara County cities)
- Floor area ratio (FAR) calculation table
- Total proposed and existing impervious surface areas
Pro tip: Check whether your city requires a separate grading plan or allows drainage information on the site plan — conflating the two is one of the fastest ways to trigger a correction letter before technical review even begins.
If your lot has any significant grade changes, review the topographic survey requirements for sloped lots in the Bay Area before finalizing your site plan drawings. A missing topo survey on a sloped lot is an automatic rejection in most cities.
Site Plan Requirements by Bay Area City: A Side-by-Side Look
This is where the site plan requirements for ADU permits in the Bay Area get genuinely city-specific. The table below captures the most-checked parameters across major jurisdictions. Verify current requirements directly with your local building department — codes update frequently and what was true last year may not be true today.
| City | Min. ADU Rear Setback | Max Lot Coverage | Topo Survey Required? | Special Site Plan Notes |
|---|---|---|---|---|
| San Jose | 4 ft | 50% (residential zones) | Yes, slopes >10% | Stormwater management plan required for lots over 5,000 sq ft |
| Oakland | 4 ft | 40–60% (varies by zone) | Yes, slopes >15% | Wildfire Hazard Zone overlay notes required for hillside parcels |
| San Francisco | 3 ft (rear yard 25% rule) | Per Planning Code §134 | Case-by-case | Horizontal plan (property survey) often required as separate document |
| Palo Alto | 5 ft | 40% | Yes, any graded site | Solar access diagram required directly on site plan sheet |
| San Mateo | 4 ft | 50% | Yes, slopes >10% | Utility stub-out locations must be dimensioned on site plan |
| Santa Clara | 5 ft | 40% | Case-by-case | Tree protection plan required if protected trees are within 50 ft |
| Fremont | 5 ft | 50% | Yes, slopes >10% | Fire access route must be fully dimensioned on site plan |
Understanding how lot coverage is calculated on a Bay Area site plan is critical before you finalize your ADU footprint. Getting that number wrong means your project may not fit within the zoning envelope — and you won't find out until plan check.
What Actually Gets Projects Rejected at Plan Check
Real projects teach the best lessons. These are the most common failure points that push ADU site plans back to the drawing board across Bay Area building departments.
Setback and Lot Coverage Errors
These two issues cause more first-submission rejections than anything else:
- Wrong setback baseline — measuring from the fence line instead of the legal property line
- Omitting setbacks from all four sides (many submittals only show rear and one side)
- Failing to account for roof overhangs when calculating setback compliance
- Lot coverage that exceeds the zoning limit once the ADU footprint is added
- Not including existing impervious surfaces — driveways, patios, sheds — in the lot coverage total
For a broader look at what trips up full permit sets, the guide on common reasons Bay Area permit sets get rejected at plan check is worth reading before you submit anything.
Missing Utility Information
Building departments want to see exactly how your ADU connects to existing services:
- Water and sewer service line locations and connection points to existing mains
- Electrical panel location and whether a panel upgrade is required
- Gas meter location if the ADU uses any gas appliances
- Stormwater discharge direction and outfall point from the ADU
Warning: Omitting the sewer lateral location is one of the fastest ways to receive a correction — some cities won't advance the application until a licensed plumber verifies the existing lateral can serve the additional unit.
Easements are another hidden landmine on site plans. An easement running through your proposed ADU footprint can stop the project entirely. Pull your title report, mark every easement on the site plan, and label each one with its recording information. The guide on easements on site plans for Bay Area building projects explains the correct notation standards city reviewers expect to see.
Keeping Your Site Plan Accurate Through Permit Revisions
Your site plan isn't a set-it-and-forget-it document. Every correction response, design change, or engineering revision can require an updated version. Staying on top of revisions prevents cascading errors across your entire permit set.
- Version-control every sheet — use revision clouds and a delta log in the title block for every change
- Update the date stamp whenever any sheet changes, even if the site plan itself didn't
- Keep a cross-reference list of every dimension and note on other sheets that ties back to the site plan
- When you change the ADU footprint, recalculate lot coverage immediately and update the data table on the site plan
- Notify your structural engineer of any site plan change that affects foundation layout or utility routing
If you're coordinating with outside consultants, confirm that everyone is working from the same current version. A mismatch between the architectural site plan and a civil grading plan is a guaranteed correction item in every city.
For a complete picture of what belongs in your submittal alongside the site plan, see the full breakdown of ADU permit set requirements for Bay Area homeowners.
Practical Tips for a Site Plan That Passes First Review
These are the specific moves that experienced drafters use to cut correction rates on ADU site plans across Bay Area cities.
- Pull the city's ADU site plan checklist from the building department website before drawing a single line — most cities post one, and it's the definitive list.
- Scale your plan to 1"=10' or 1"=20' for typical residential lots. Don't go smaller. Reviewers need to read dimensions without a magnifying glass.
- Label every structure by use: "Existing Single-Family Residence," "Proposed Detached ADU," "Existing Detached Garage." Don't leave anything unlabeled.
- Include a small vicinity map or address callout in the title block so reviewers can orient the parcel immediately.
- Add a data summary table in the corner of the site plan sheet: lot size, existing coverage, proposed coverage, ADU square footage, setbacks from all four sides.
- Verify property lines against the recorded parcel map — not Google Maps, not county GIS. Those tools are useful for orientation but are not dimensionally accurate.
- Show the driveway and calculate total impervious surface even when the city doesn't explicitly require it. It signals thoroughness and prevents questions later.
If your city uses electronic plan submittal, flatten your PDF layers and follow the file naming convention exactly. A rejected electronic submittal for a naming error wastes a week before technical review even starts.
Planning Your Site Plan for Long-Term ADU Flexibility
Smart property owners think past the immediate permit. The decisions you make on your site plan today affect what you can do with your property in the future.
Leave Room for a Second ADU
California law allows most single-family lots to have one ADU plus one JADU. If your lot can accommodate both, position your detached ADU to preserve the interior JADU option in the primary residence. Show the potential JADU location as a dashed outline or a notation on your site plan — not because it's required, but because it forces you to confirm both units can coexist within the zoning envelope before you commit to a footprint.
Design for Future Utility Upgrades
If your electrical panel is already near capacity, show a future panel upgrade location on the site plan now. It signals to reviewers that you've planned ahead — and it saves you an amended permit when you actually need the upgrade.
- Stub out water and sewer in locations that can serve a future JADU without re-trenching the yard
- Design driveway access so that ADU tenant parking doesn't block the main residence
- Plan stormwater management for the post-ADU impervious surface total — not just today's footprint — so you don't trigger additional review requirements when you add more hardscape later
Myths About ADU Site Plans That Are Costing Homeowners Time
Misinformation about site plans spreads fast. Here are the myths that cause the most real-world damage to ADU permit timelines.
Myth 1: "The city will correct my site plan for me."
No. Plan checkers mark corrections and send your application back. They don't redraw your documents. Every correction cycle adds weeks — sometimes months — to your timeline.
Myth 2: "A Google Earth screenshot is good enough for a site plan."
Cities require measured drawings based on a recorded parcel map or licensed survey. Aerial screenshots don't contain accurate property boundary data and will never pass plan check.
Myth 3: "State ADU law eliminated local setback requirements."
State law limits how restrictive local setbacks can be, but it doesn't eliminate them. The 4-foot rear and side setback standard from state law is a floor — not a blanket override of all local rules. Your city's zoning still controls front setbacks, height, and in many cases, lot coverage.
Myth 4: "Lot coverage doesn't apply to detached ADUs."
It does apply. California law prevents cities from applying lot coverage limits that would block a minimum 800 sq ft ADU on qualifying lots — but that protection is specific to small lots, not a universal exemption from coverage calculations.
Myth 5: "A flat lot doesn't need a property survey."
Many Bay Area cities require property line verification from a recorded parcel map or licensed survey regardless of slope. Flat topography is not a substitute for confirming legal boundaries.
Frequently Asked Questions
Most Bay Area cities accept site plans at 1"=10', 1"=20', or 1"=30' depending on lot size. Larger lots may use 1"=40'. Always confirm the acceptable scale with your specific city's building department — most post this in their ADU checklist or plan check submittal guide.
Not always — but you need accurate property line data from a reliable source. Most cities accept site plans prepared by a drafter or architect as long as the boundaries are based on a recorded parcel map. If property lines are disputed, unclear, or the lot was recently subdivided, a licensed survey is required. Some cities require a survey for all ADU projects regardless of lot history.
The ADU footprint — the ground floor area under the structure, including covered porches and attached carports — is added to all other impervious structures on the lot. The combined total is divided by the gross lot area to get your coverage percentage. California law prevents cities from applying coverage limits that would block a minimum 800 sq ft ADU on qualifying lots, but overall coverage limits still apply in most situations.
California state law sets a minimum standard of 4-foot rear and side setbacks for detached ADUs. However, cities like Palo Alto, Santa Clara, and Fremont apply 5-foot minimums. Front setbacks follow standard residential zoning rules — ADUs are generally not permitted in the front yard setback area. Always verify current setback requirements with your city before finalizing any site plan dimensions.
Yes — most Bay Area cities now accept or require electronic plan submittal through portals like ePlan, ProjectDox, or their own city-specific platforms. Your PDF must be drawn to scale, properly layered or flattened, and meet the city's file naming and size requirements. San Jose, Oakland, and San Francisco all publish electronic submittal guides through their building department websites.
No. The site plan shows only the exterior footprint of the ADU as positioned on the lot — not what's inside. Interior floor plans, elevations, and building sections are separate sheets in the permit set. The site plan's purpose is to document the relationship between your proposed structure, existing structures, and the property boundaries.
Next Steps
- Download your city's ADU site plan checklist from the building department website and verify every required element against your current drawings before you submit anything.
- Pull your recorded parcel map from the county recorder's office and confirm your property line dimensions — don't rely on GIS tools or online map services for legal boundary data.
- Calculate your lot coverage now, before design is locked in. Add up all existing impervious structures plus your proposed ADU footprint and check the total against your zone's maximum allowance.
- Review your title report for easements and mark every one on a rough sketch of your lot. Any easement running through your proposed ADU placement needs to be resolved before you finalize the footprint.
- Contact Sunny Drafting & Design to have a complete, city-compliant ADU site plan prepared — visit our ADU and JADU design page to get started and give your permit the best possible chance of passing first review.
