When Should You Order a Survey for Your ADU Project?

Why Timing Your Property Survey Matters for ADU Success

A property survey is one of the first professional services you should invest in when planning an ADU project. Yet many homeowners either delay ordering their survey too long or are unsure about what type of survey they actually need. Getting the timing right can save you weeks of delays and thousands of dollars in redesign costs.

In this guide, we will cover everything you need to know about property surveys for ADU projects: the different types available, when to order each one, what they cost, and what surveyors actually look for on your property. Whether you are in the early research phase or ready to start design, this information will help you make smart decisions about your survey investment.

Types of Surveys for ADU Projects

Not all surveys are created equal. The type of survey you need depends on your property's characteristics, your city's requirements, and the complexity of your ADU project.

1. Boundary Survey

A boundary survey establishes the exact legal boundaries of your property. The surveyor locates existing property corner monuments, reviews your deed and any recorded subdivision maps, and determines the precise location of your property lines.

What it includes:

• Location and marking of all property corners
• Measurement of property dimensions
• Total lot area calculation
• Identification of any encroachments (your structures on neighboring property or vice versa)
• Recorded easement locations

Cost: $500 to $1,500 for a typical residential lot in California

Timeline: 1 to 2 weeks from order to delivery

2. Topographic Survey

A topographic (topo) survey maps the elevation changes across your property. This is critical for drainage planning, foundation design, and compliance with grading requirements.

What it includes:

• Elevation contours (usually at 1-foot intervals)
• Location and elevation of existing structures
• Existing hardscape features (driveways, patios, walkways)
• Drainage flow patterns
• Location of significant trees and landscaping

Cost: $1,000 to $3,000 depending on lot size and complexity

Timeline: 1 to 3 weeks

3. Combined Boundary and Topographic Survey

This is the most common survey type for ADU projects and offers the best value. It combines the boundary and topographic surveys into a single deliverable, giving your architect or designer everything they need in one document.

Cost: $1,500 to $4,000 (less than ordering each separately)

Timeline: 2 to 3 weeks

4. ALTA/NSPS Land Title Survey

This is the most comprehensive survey type, following standards set by the American Land Title Association and the National Society of Professional Surveyors. It is typically required for commercial transactions but may be valuable for complex residential properties.

What it includes (beyond standard surveys):

• All recorded easements and encumbrances
• Rights of way
• Evidence of utilities
• Flood zone determination
• Relationship to surrounding parcels

Cost: $2,000 to $5,000

Timeline: 2 to 4 weeks

5. As-Built Survey

An as-built survey documents existing structures and improvements on the property. This is particularly useful if you are planning a garage conversion or adding an attached ADU.

Cost: $800 to $2,000

Timeline: 1 to 2 weeks

Survey Type	Best For	Cost Range	Turnaround
Boundary Only	Flat lots, simple projects	$500 to $1,500	1 to 2 weeks
Topographic Only	Known boundaries, sloped lots	$1,000 to $3,000	1 to 3 weeks
Combined Boundary + Topo	Most ADU projects	$1,500 to $4,000	2 to 3 weeks
ALTA/NSPS	Complex properties	$2,000 to $5,000	2 to 4 weeks
As-Built	Conversions, attached ADUs	$800 to $2,000	1 to 2 weeks

When to Order Your Survey

The ideal timing for ordering your survey depends on where you are in the ADU development process. Here is a timeline showing when each survey type should be ordered:

Phase 1: Early Planning (Before Hiring a Designer)

Order your boundary survey during the early planning phase, ideally before you hire an architect or designer. This allows you to:

• Confirm your property dimensions and available building area
• Identify any easements or encroachments that could affect ADU placement
• Provide accurate information to potential designers and contractors when requesting proposals
• Make informed decisions about ADU size and placement before investing in design

Phase 2: Pre-Design (Before Design Begins)

Order your topographic survey (or combined boundary/topo survey if you have not already done the boundary survey) before your designer begins schematic design. Your architect needs this information to:

• Establish the correct floor elevation for the ADU
• Plan drainage and grading
• Determine foundation type and depth
• Ensure the ADU design complies with height limits relative to existing grade

Phase 3: Post-Design (Before Permit Submittal)

If your city requires a formal survey as part of the permit application, make sure the survey is current (typically within one year of the permit submittal date). Some cities require a certified survey stamped by a licensed surveyor as part of the plan check package.

What Surveyors Look for on Your Property

When a surveyor visits your property, they are looking for specific features and conditions. Understanding what they do will help you prepare for the visit and ensure a productive survey.

Property Corners and Monuments

Surveyors search for existing property corner monuments, which may be iron pins, rebar, concrete markers, or other markers set by previous surveys. These are typically buried a few inches below grade. If original monuments cannot be found, the surveyor will use mathematical calculations based on the recorded subdivision map and adjacent surveys to re-establish the corner locations.

Existing Improvements

The surveyor will locate and measure all existing structures and improvements, including:

• Main house and any additions
• Garage, carport, or covered parking
• Fences, walls, and retaining walls
• Driveways, patios, and walkways
• Pools, spas, and water features
• Significant trees (typically those over 6 inches in diameter)
• Utility meters, manholes, and cleanouts

Elevation and Grade

For topographic surveys, the surveyor takes elevation readings at regular intervals across the property. They use GPS equipment, total stations, or laser levels to capture the terrain. Key elevation points include:

• Existing building floor elevations
• Curb and gutter elevations at the street
• High and low points on the property
• Drainage flow patterns and collection points

How to Prepare for Your Survey Visit

You can help the survey go smoothly and potentially save money by preparing your property:

1. Clear access to property corners: Remove any planters, debris, or stored items near where property corners are likely located (usually at the lot's four corners)
2. Mark known features: If you know where your sewer cleanout or water shutoff valve is, mark it with a flag or spray paint
3. Provide gate access: If the surveyor needs to access side or rear areas through locked gates, make arrangements for access
4. Gather documents: Have your deed, any previous surveys, and title documents available for the surveyor to review
5. Inform neighbors: The surveyor may need to access adjacent properties to locate shared property corners, so a heads-up to neighbors is courteous
6. Secure pets: Keep dogs and other pets inside or in a secure area away from where the surveyor will be working

What Affects Survey Cost

Several factors influence how much your survey will cost:

Factor	Impact on Cost	Explanation
Lot Size	Moderate	Larger lots require more time to survey
Terrain Complexity	High	Hillside or heavily vegetated sites cost more
Monument Availability	Moderate	Missing corner monuments add research time
Number of Improvements	Moderate	More structures to locate means more time
Rush Service	High	Expedited service typically adds 50% to 100%
Location	Moderate	Urban areas may cost more than suburban

How to Choose the Right Surveyor

Selecting a qualified surveyor is important for getting accurate and useful results. Here are the key qualifications to look for:

• Professional Land Surveyor (PLS) License: Required in California for anyone preparing official surveys. Verify their license through the California Board for Professional Engineers, Land Surveyors, and Geologists
• ADU experience: Surveyors familiar with ADU projects understand what information architects and the building department will need
• Local knowledge: A surveyor who regularly works in your city will be familiar with local requirements, common issues, and the city's survey standards
• Digital deliverables: Ensure the surveyor can provide AutoCAD (.dwg) files in addition to printed plans, as your architect will need the digital file for design work
• Insurance: Professional liability insurance protects you if an error in the survey causes problems during your project

Common Survey Issues That Affect ADU Projects

Surveys sometimes reveal unexpected issues that can impact your ADU project:

Encroachments

A neighbor's fence, wall, or structure may be built partially on your property, or vice versa. Encroachments need to be resolved before construction, either through removal or a written agreement between property owners.

Easement Conflicts

Recorded easements may limit where you can build. If your planned ADU location falls within an easement, you will need to redesign or seek a vacation or relocation of the easement.

Lot Area Discrepancies

The actual lot area measured by the surveyor may differ from what is recorded in tax records or real estate listings. This can affect your maximum ADU size if local regulations tie ADU size to lot area percentages.

Grade Issues

The survey may reveal significant grade changes that were not apparent to the naked eye. A slope of even 5% to 10% can significantly impact foundation design and construction costs.

How Surveys Relate to the Permit Process

Your survey plays a direct role in the permitting process. The ADU permit application typically requires a site plan that shows the proposed ADU in relation to property boundaries, setback lines, and existing structures. This site plan is based directly on your survey.

Some cities require a certified survey as part of the permit application, while others accept a site plan prepared by an architect or designer based on a survey. In Los Angeles, the Department of Building and Safety generally requires a site plan with accurate dimensions but may not always require a formal certified survey for straightforward ADU projects.

Conclusion

Ordering the right survey at the right time is one of the smartest investments you can make in your ADU project. A combined boundary and topographic survey ordered during the pre-design phase gives your architect the accurate site information they need to design efficiently and avoid costly revisions later.

Budget $1,500 to $4,000 for a quality survey, allow 2 to 3 weeks for completion, and choose a licensed surveyor with local ADU project experience. The information your survey provides will pay for itself many times over by preventing setback violations, drainage issues, and other problems that could derail your project.

What to Do If the Survey Reveals Problems

Sometimes a property survey uncovers issues that complicate your ADU plans. Here is how to handle the most common problems that California homeowners face after receiving their survey results.

Encroachments

An encroachment occurs when a structure, fence, or landscape feature crosses a property boundary. If your neighbor's fence is on your property (or vice versa), this needs to be resolved before ADU construction. Options include negotiating with the neighbor to relocate the encroachment, documenting it with a written agreement, or in some cases, applying for an encroachment permit. Do not ignore encroachments, as they can create legal complications during and after construction.

Easement Conflicts

Your survey may reveal easements that restrict where you can build. Common easements include utility easements (for power, water, or sewer lines), access easements (granting neighbors passage through your property), and drainage easements. If your proposed ADU footprint overlaps with an easement, you will need to redesign or apply for an easement modification. Utility companies rarely agree to relocate their easements, so plan around them from the start.

Lot Size Discrepancies

It is not uncommon for the actual lot size to differ from what is recorded on the assessor's map. If your lot turns out to be smaller than expected, you may need to adjust your ADU size or reconsider placement. On the positive side, some homeowners discover their lot is larger than recorded, which can open up additional design options. Either way, the survey ensures you are working with accurate dimensions.

Slope and Grading Issues

A topographic survey may reveal slope conditions that affect your foundation design and construction costs. Lots with more than a 10 percent grade change across the building area typically require engineered retaining walls, deeper foundations, or stepped foundation designs. These add cost but are manageable with proper planning. Discuss grading findings with your designer early to avoid budget surprises.

Cost-Saving Tips for ADU Surveys

Professional surveys are a necessary investment, but you can optimize your spending with these strategies.

• Bundle services: Order your boundary survey, topographic survey, and utility locate at the same time. Most survey firms offer discounts for combined services, and you save on mobilization costs
• Get multiple quotes: Survey costs vary significantly between firms. Get at least three quotes and compare scope, not just price. A cheaper survey that misses critical details is no bargain
• Check if a recent survey exists: If you purchased your home within the last two to three years, a survey may have been done as part of the closing process. Contact your title company or previous owner to find out
• Prepare the site beforehand: Clear brush, move vehicles, and ensure all property corners are accessible before the surveyor arrives. Time spent by the survey crew clearing obstacles adds to your bill
• Ask about survey reuse: If you already have a boundary survey and only need topographic data added, some firms will update the existing survey at a reduced rate

Understanding your survey costs in context is important. For a full picture of pre-construction expenses, review our guide on hidden ADU costs before breaking ground.

Frequently Asked Questions: ADU Surveys

How long does a property survey take for an ADU project?

Field work typically takes one to two days for a standard residential lot. Processing the data and producing the final survey document usually takes an additional one to two weeks. If your lot is larger, has irregular boundaries, or requires additional research into historical records, the timeline can extend to three to four weeks. Plan accordingly and order your survey early in the planning process.

Do I need a new survey if I already had one done for my home purchase?

If the survey was done within the past two to three years and no significant changes have occurred on the property or adjacent properties, your existing survey may be sufficient. However, most ADU projects benefit from adding topographic data and utility locations to an existing boundary survey. Consult with your designer and the survey firm to determine what additional work, if any, is needed.

What is the difference between a boundary survey and a topographic survey?

A boundary survey establishes the legal property lines and locates existing structures relative to those lines. A topographic survey maps the elevations and contours of the land, showing slopes, drainage patterns, and natural features. For ADU projects, you typically need both. The boundary survey ensures your ADU meets setback requirements, while the topographic survey informs foundation design and grading plans.

Can my ADU designer or architect handle the survey?

No. In California, only a licensed Professional Land Surveyor (PLS) can perform boundary surveys and certify property dimensions. Your designer or architect can recommend a surveyor and will use the survey data in their design work, but the survey itself must be performed by a licensed professional. This is a legal requirement, not just a best practice.

What happens if my survey shows I cannot fit an 800 sq ft ADU on my property?

If setbacks, easements, or lot dimensions limit your buildable area, you still have options. Consider a smaller ADU design, a Junior ADU (JADU) of up to 500 square feet within your existing home, a garage conversion, or a two-story design that maximizes floor area on a smaller footprint. California law protects your right to build at least an 800-square-foot ADU in most cases, so work with your designer to explore creative solutions. For more on ADU sizing, see our article on how big is 400 square feet.

Should I share the survey results with my neighbors?

While you are not legally required to share your survey with neighbors, doing so can prevent disputes and build goodwill. If the survey reveals that a shared fence is not on the property line, discussing this with your neighbor before construction starts is much better than dealing with a complaint or legal challenge later. Transparent communication with neighbors is one of the best investments you can make in a smooth ADU project.