What Happens If Plan Check Finds Property Line Issues?

Property Line Problems During ADU Plan Check

You have spent months designing your ADU, hired an architect, and submitted your plans to the building department. Then you receive a correction letter that stops you cold: the plan checker has identified a property line issue. Maybe your proposed ADU is too close to a property line. Maybe the survey shows a discrepancy with the assessor's records. Or maybe an existing structure is encroaching on your neighbor's property, and now the city wants it resolved before they will approve your ADU.

Property line issues are among the most complex and time-consuming problems that can arise during ADU plan check. Unlike straightforward corrections to your plans (like adding a detail or fixing a calculation), property line disputes can involve surveying, negotiations with neighbors, title insurance claims, and sometimes even legal proceedings.

In this comprehensive guide, we will cover the most common property line issues that surface during ADU plan check, explain how each one affects your project, and provide actionable strategies for resolution. Whether you are dealing with an unclear boundary, an existing encroachment, or a setback measurement dispute, this guide will help you navigate the situation effectively.

Types of Property Line Issues in ADU Plan Check

1. Survey Discrepancies

One of the most common property line issues occurs when the survey submitted with your ADU plans does not match the city's records. This can happen for several reasons. Older surveys may have used different measurement techniques or reference points. Over the decades, monuments (the physical markers that define property corners) can be moved, damaged, or buried. Additionally, the legal description of your property in the deed may not perfectly align with what is physically on the ground.

When a plan checker identifies a survey discrepancy, they will typically require you to provide additional documentation, such as a boundary survey by a licensed land surveyor that addresses the discrepancy. This is not a standard topographic survey. A boundary survey is a legal determination of property lines based on deed research, monument recovery, and field measurements.

Survey Type	Purpose	Typical Cost	Timeline
Topographic Survey	Shows existing conditions, elevations	$500 - $1,500	1-2 weeks
Boundary Survey	Legally determines property lines	$2,000 - $5,000	2-4 weeks
ALTA/NSPS Survey	Comprehensive survey for transactions	$3,000 - $7,000	3-6 weeks
Record of Survey	Filed with county for new monuments	$4,000 - $8,000	4-8 weeks

2. Existing Encroachments

An encroachment occurs when a structure, fence, or improvement extends beyond your property line onto your neighbor's property (or vice versa). During ADU plan check, the city may discover that an existing fence is not on the property line, your existing home or garage encroaches on a neighbor's lot, a neighbor's structure encroaches onto your property, or existing hardscape (driveways, patios, retaining walls) crosses the property line.

The existence of encroachments can affect your ADU project in several ways. If the encroachment reduces the usable area of your lot, it may affect where you can place the ADU or whether you meet minimum lot size requirements. If the city requires resolution of the encroachment before issuing your ADU permit, you will need to negotiate with your neighbor.

3. Easement Conflicts

Easements are legal rights for someone other than the property owner to use a portion of your property for a specific purpose. Common easements that affect ADU projects include utility easements (for water, sewer, gas, or electric lines), drainage easements, access easements (allowing a neighbor to cross your property), and alley easements. You generally cannot build within an easement. If your proposed ADU location conflicts with an existing easement, the plan checker will require you to either relocate the ADU or obtain an easement modification or abandonment.

Strategies for Resolving Property Line Issues

Strategy 1: Get a Boundary Survey Immediately

If the plan checker has flagged a property line issue, your first step should be to hire a licensed California land surveyor to perform a boundary survey. This is different from the topographic survey that was likely included with your initial plans. A boundary survey involves researching the legal descriptions and recorded surveys for your property and all adjoining properties, recovering or re-establishing property corner monuments, calculating the boundary based on deed records and field evidence, and preparing a detailed survey map showing the true property lines.

The boundary survey will either confirm that your original survey was correct (giving you evidence to present to the plan checker) or reveal the actual location of the property lines, allowing you to adjust your ADU design accordingly.

Strategy 2: Negotiate an Encroachment Agreement

If an existing encroachment is discovered, one option is to negotiate an encroachment agreement with your neighbor. This is a written agreement, typically recorded against both properties, that acknowledges the encroachment and sets terms for its continued existence. An encroachment agreement does not change the property line but provides legal protection for both parties.

Common terms in encroachment agreements include acknowledgment of the encroachment by both parties, agreement to allow the encroachment to remain for a specified period or until the structure is removed, indemnification provisions, and provisions for maintenance and insurance.

Encroachment agreements typically cost $1,500 to $3,000 in legal fees to prepare and record. Your city may or may not accept an encroachment agreement as sufficient to resolve a plan check correction. Check with the plan checker before investing in this approach.

Strategy 3: Relocate or Resize Your ADU

Sometimes the simplest solution to a property line issue is to adjust your ADU's location or size. If your proposed ADU is too close to a property line that is in a different location than originally thought, moving the ADU a few feet may resolve the issue. This may require redesign work (and additional design fees), but it is often faster and cheaper than resolving a boundary dispute.

California's ADU setback requirements are relatively generous. State law allows a maximum 4-foot rear and side setback requirement for detached ADUs. If you have room to move your ADU further from the disputed line while still meeting setback requirements, this may be the most efficient path forward. Be sure to also consider roof overhang setback rules when repositioning your ADU.

Strategy 4: Lot Line Adjustment

In cases where the true property line is significantly different from what was assumed, you and your neighbor may agree to a lot line adjustment. This is a formal process that changes the legal boundary between two properties by mutual agreement. Lot line adjustments require approval from the local planning department and recording of a new subdivision map or parcel map.

This is a more complex and expensive option (typically $5,000 to $15,000 including surveying, legal fees, and city processing fees), but it provides a permanent, legally binding solution to the property line issue.

How to Prevent Property Line Issues Before Plan Check

The best approach to property line issues is to identify and resolve them before you submit your ADU plans. Here is how:

Get a Survey Early

Before you start designing your ADU, invest in a quality survey that includes property corner identification. Ideally, this survey should recover (or set new) property corner monuments and clearly show the relationship between your property lines and all existing structures, fences, and improvements. This initial investment of $1,000 to $3,000 can save you months of delays and thousands in additional costs later.

Walk the Property Lines

After the surveyor has marked the property corners, physically walk your property lines and compare what you see on the ground with what the survey shows. Look for fences that do not align with the survey markers, structures that appear to be close to or over the property line, utility boxes, meters, or other improvements that might indicate easements, and any evidence of neighbor structures crossing onto your property.

Check Easements with the County Recorder

Obtain a preliminary title report (about $150 to $300 from a title company) that lists all recorded easements, liens, and encumbrances on your property. Provide this information to your architect so they can design around any easements.

Talk to Your Neighbors

Before you submit plans, have a conversation with your adjacent neighbors about your ADU project. If there are any boundary disputes or concerns, it is better to learn about them early. Neighbors who feel informed and respected are more likely to cooperate if a property line issue arises.

How Property Line Issues Affect Your ADU Timeline

Issue Type	Typical Resolution Time	Estimated Cost
Survey discrepancy (minor)	2-4 weeks	$2,000 - $4,000
Encroachment agreement	4-8 weeks	$2,000 - $5,000
ADU relocation/redesign	2-6 weeks	$2,000 - $8,000
Lot line adjustment	3-6 months	$5,000 - $15,000
Boundary dispute (contested)	6-18 months	$10,000 - $50,000+

As you can see, preventing property line issues through upfront due diligence is far more cost-effective than resolving them after they are flagged during plan check.

Frequently Asked Questions

Can the city require a survey for my ADU application?

Yes, most California cities require a property survey as part of the ADU plan submittal. At minimum, a topographic survey showing property lines, existing structures, and elevations is typically required. Some cities may require a full boundary survey, especially if there is any question about the accuracy of the property lines. Check your city's ADU application requirements before designing.

What if my neighbor disputes the property line during my ADU project?

If your neighbor raises a property line dispute, the building department will typically put your permit application on hold until the dispute is resolved. This does not necessarily require a lawsuit. Many boundary disputes can be resolved through a joint boundary survey (where both property owners agree to accept the results), mediation, or a negotiated encroachment agreement. Only escalate to litigation as a last resort.

Can I build an ADU within an easement?

Generally, no. Building within a recorded easement is typically prohibited because the easement holder has a legal right to use that portion of your property. However, some easements can be relocated, modified, or abandoned. If your preferred ADU location conflicts with an easement, contact the easement holder (usually a utility company) to discuss whether modification is possible.

Does a fence on the property line count as a setback reference point?

No. Setbacks are measured from the legal property line as determined by a licensed survey, not from a fence. Fences are often not located exactly on the property line. Relying on a fence as a property line reference is one of the most common mistakes in ADU design and a frequent cause of plan check corrections.

What if my property survey shows I have less land than I thought?

If a survey reveals that your lot is smaller than recorded, this may affect your ability to build an ADU of the desired size. California law does not have a minimum lot size requirement for ADUs on single-family lots, but the reduced lot size may affect setback calculations, lot coverage limits, and floor area ratios. Discuss the implications with your architect and designer. Learn about the full ADU permit process in our detailed guide.

Should I get title insurance for my ADU project?

Title insurance is not typically required for ADU construction (it is primarily associated with property purchases). However, if your ADU project uncovers title issues such as unrecorded easements, boundary disputes, or ownership questions, a title search (about $150 to $300) can help identify and resolve these issues. Your title insurance from when you purchased the home may also provide some protection against boundary-related claims.

Resolution Strategies for Property Line Issues During Plan Check

Discovering property line discrepancies during plan check does not have to derail your ADU project. Here are proven strategies for resolving boundary issues efficiently.

Obtain a Licensed Land Survey

The most definitive way to resolve a property line dispute is to hire a licensed land surveyor. A professional survey establishes the legal boundaries of your property based on recorded deeds and monuments. While surveys typically cost $500 to $2,000, they provide documentation that your city's building department will accept as authoritative evidence of your property boundaries. If the survey reveals that your property is larger than what assessor records show, you may gain additional buildable area for your ADU.

Negotiate a Lot Line Adjustment

If a survey reveals that a fence, wall, or other improvement encroaches across the property line, you and your neighbor may agree to a lot line adjustment. This process redraws the legal boundary between your properties to match the existing conditions. Lot line adjustments require approval from your city's planning department and must be recorded with the county recorder. The process typically takes two to four months and costs $1,000 to $3,000 in application fees and surveying costs.

Record an Encroachment Agreement

When an existing structure slightly crosses a property line and a lot line adjustment is not practical, an encroachment agreement can formalize the arrangement. This legal document, signed by both property owners and recorded with the county, acknowledges the encroachment and sets terms for its continuation. While this does not move the property line, it creates a legal record that can satisfy building department requirements for ADU permitting.

Redesign Your ADU Placement

Sometimes the simplest solution is to adjust your ADU's location on the property to avoid the disputed boundary area entirely. Moving the ADU even a few feet can resolve setback compliance issues without the time and expense of boundary disputes. Work with your architect to explore alternative placements that maintain your desired floor plan while meeting all setback requirements. For more on setback compliance, see our guide on setback rules for ADU roof overhangs.

Frequently Asked Questions

How long does it take to resolve a property line issue during plan check?

Resolution timelines vary depending on the approach. A licensed land survey can be completed in two to four weeks. Lot line adjustments typically take two to four months for city approval and recording. Encroachment agreements require both parties to negotiate terms, which can take anywhere from a few weeks to several months. During this time, your ADU permit application is usually placed on hold rather than denied.

Will the city reject my ADU permit if there is a property line dispute?

The city will not approve your permit until the property line issue is resolved, but they typically will not reject the application outright. Instead, your application will be placed on hold with a correction notice explaining what documentation is needed. You will have a set period, usually 60 to 180 days, to provide the required information before the application expires. If you need help navigating a denial, read our guide on what happens if the city denies your ADU application.

Can my neighbor block my ADU project by disputing the property line?

A neighbor cannot unilaterally block your ADU project by claiming a property line dispute. If you have a valid survey showing your ADU meets setback requirements, the building department will rely on that professional documentation. Neighbors do not have approval authority over ADU permits under California state law. However, unresolved disputes can cause delays, so addressing boundary concerns proactively is always recommended.

Do I need a survey if my property has an existing fence on the boundary?

Fences are not reliable indicators of property boundaries. Many fences are installed based on visual estimates rather than surveyed property lines. If your ADU will be built near a property boundary marked only by a fence, a professional survey is strongly recommended. The cost of a survey is minimal compared to the potential expense of building in the wrong location and having to modify or relocate your ADU.

What if the survey shows my lot is smaller than I thought?

If a survey reveals your lot is smaller than expected, your ADU plans may need to be adjusted to meet setback and lot coverage requirements. Work with your architect to redesign the ADU footprint or consider building a two-story unit to maintain square footage with a smaller ground-floor footprint. In some cases, a smaller lot may still accommodate a full-sized ADU under California's generous state ADU laws. Review your options in our article on local ADU rules vs. California state law.