Do I need a land survey to build an ADU in Los Angeles?

Does LADBS require a survey for an ADU permit?

Not as a blanket rule. The LADBS checklist for an ADU built from a standard plan says every item must be shown to scale on the plot plan, starting with the property lines with dimensions and the front, side and rear setbacks ¹. As of October 2026, we did not find an LADBS document that requires a licensed survey for every ADU.

The plan checker can still ask for one. The LADBS correction sheet for ADUs lists a topography survey map and a survey analysis map among the documents a plan checker can require with each set of plans ². The same sheet asks for a fully dimensioned plot plan that shows the legal description, building lines, easements, lot size, and the setbacks of every building ⁷.

On a flat lot where the backyard house sits well inside every limit, a plot plan drawn from the recorded maps may be all anyone asks for. When the design depends on the last foot of the yard, it is not enough, and a survey is how a designer gets the numbers right.

When does the exact property line matter for a backyard house?

It matters whenever a wall, a window or the whole building sits near a distance the code measures from the line. On an ADU in Los Angeles, these are the ones that come up most:

• 4 feet: the correction sheet asks for a minimum 4-foot setback from the rear and side property lines for new construction or an addition ⁴.
• 5 feet: an exterior wall less than 5 feet from the property line needs a 1-hour fire-resistance rating ⁵.
• 10 feet: any work in or within 10 feet of an LADWP easement needs written approval from LADWP ⁶.
• Height: on a sloped lot, the plan checker can ask for a topographic map with the building outlined to determine its height ³.

If the plan puts a wall at 4 feet 3 inches, a few inches of error in where the line really is decides whether the plan passes. If the backyard house sits 12 feet from every line, it does not. Our setback guide explains what each distance allows, including the different rules for a garage conversion, and our height guide explains how the city measures height.

What kinds of survey are there, and which one does an ADU need?

Three kinds come up on ADU projects. A San Diego ADU builder describes them this way:

• Boundary survey: formally locates the property lines of the parcel ⁸.
• Planimetric and limited topographic survey: maps the buildings, trees, driveways and other features, and adds elevations for the foundation and drainage design ⁹.
• Building verification survey: confirms, once the foundation forms are set, that the unit sits where the plans say ¹⁰.

Which one you need depends on the question. A tight setback calls for a boundary survey. A sloped lot or a height limit calls for topography. A city or an inspector who wants proof of placement asks for verification.

In California, locating or retracing a property line is land surveying under state law ¹⁷. It is unlawful to practice or offer it without a license unless the law specifically exempts you ¹⁸. When a surveyor's fieldwork turns up a material discrepancy with the recorded maps, the surveyor must file a record of survey with the county surveyor ¹⁹²⁰.

How much does a survey for an ADU cost?

We found no Los Angeles surveyor that publishes a price, and the published figures we did find are far apart. Use them to know what to ask, not as a budget.

• A San Diego ADU builder lists a boundary survey at $2,500 to $12,500, case by case ¹¹, and says a boundary survey plus a building verification survey usually costs $4,000 to $10,000 together ¹³.
• A Beverly Hills real estate agent, writing about surveys for home sales, says a land survey typically runs $500 to $1,500 or more, depending on the size, terrain and complexity of the property ¹⁵.

Part of the gap is scope. A survey for a sale may stop at the boundary, while an ADU designer may also want topography and the position of the house, the garage and the trees. The builder also says the price depends mostly on the earlier surveys recorded with the county surveyor ¹², which is why the records in the next section are worth looking up first.

Time matters too. By the same builder's account, fieldwork takes 1 to 2 days and compiling and recording the results takes 1 to 2 weeks ¹⁴. The state treats a survey as an ordinary early cost: HCD's ADU handbook lists property surveys among predevelopment costs, next to designs, permits, soil tests and impact fees ¹⁶. Our soft costs guide shows where a survey sits in the rest of the budget.

Has my lot been surveyed before, and can I see the records?

Often yes, and LA County Public Works posts the records online as free downloads. Records of survey are filed by book and page, so RS123-011 is Record of Survey Book 123, Page 011 ²³. Tract maps are posted the same way: TR 1268-011 is Map Book 1268, Page 011 ²⁴.

1. Find your tract and lot number in the legal description on your deed, the same description LADBS wants on the plot plan ⁷.
2. Download the tract map from LA County Public Works and read your lot's recorded dimensions ²⁴.
3. Ask whether a record of survey covers your block. A surveyor who found a material discrepancy with the recorded maps had to file one ¹⁹²⁰.
4. Compare the recorded dimensions with what you measure along the fence and the house.
5. Bring what you find when you ask a surveyor for a quote, since recorded surveys nearby are what the builder above says drives the price ¹².

None of this replaces a survey. It tells you whether the paper and the ground agree, and how much work a surveyor is likely to face.

What is not a survey?

Several things look like a property line and are not one.

• The Assessor's parcel map. The County Assessor says its parcels are for tax assessment purposes only and are not necessarily survey grade ²¹. A former chief cadastral engineer of its mapping office describes most of the data as accurate within a couple of feet ²². A couple of feet is half of a 4-foot setback.
• The fence. Fences are often not on the line, which is why the setback guide says to measure from the actual property line.
• An aerial image or a map app. It shows roughly where things are. Locating a property line is land surveying, and that takes a licensed surveyor ¹⁷¹⁸.
• An old plot plan. A plot plan in your permit history shows where someone drew the line for an earlier project. It is a good starting point, not a measurement. Our garage permit guide explains how to find one.
• A lot check. A lot check, including ours, does not survey anything and does not locate property lines. Whether your plan sits close enough to a line that a licensed survey is worth buying is the kind of thing a lot check settles.

When should I pay for a survey before the plans are drawn?

Pay for one early when the answer could change the design. That usually means one of these:

• The backyard house or an addition would sit within a few feet of the 4-foot setback or the 5-foot fire-rating line ⁴⁵.
• The lot slopes and the unit is close to its height limit ³.
• An LADWP easement or another recorded easement crosses the yard ⁶⁷.
• The fence, the Assessor's map and the tract map disagree about where the line is ²¹²⁴.

If none of these apply, a plot plan drawn from the recorded maps may carry you through plan check, and the correction sheet is where a plan checker would ask for a survey map if one is needed ².

Quick answers

Sources

1. ADU Standard Plan: Building Permit Submittal Checklist, LADBS. Facts checked 2026-10-10
2. Plan Check Correction List: Accessory Dwelling Units (PC/STR/Corr.Lst.20A, rev. 10/01/2025), LADBS. Facts checked 2026-10-10
3. Plan Check Correction List: Accessory Dwelling Units (PC/STR/Corr.Lst.20A, rev. 10/01/2025), LADBS. Facts checked 2026-10-10
4. ADU, JADU and Movable Tiny House Correction Sheet (rev. 10/01/2025): side and rear setbacks, LADBS. Facts checked 2026-10-10
5. Plan Check Correction List: Accessory Dwelling Units (PC/STR/Corr.Lst.20A, rev. 10/01/2025), LADBS. Facts checked 2026-10-10
6. Plan Check Correction List: Accessory Dwelling Units (PC/STR/Corr.Lst.20A, rev. 10/01/2025), LADBS. Facts checked 2026-10-10
7. Plan Check Correction List: Accessory Dwelling Units (PC/STR/Corr.Lst.20A, rev. 10/01/2025), LADBS. Facts checked 2026-10-10
8. When do you need a survey for an ADU in San Diego? (boundary survey), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
9. When do you need a survey for an ADU in San Diego? (planimetric and topographic survey), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
10. When do you need a survey for an ADU in San Diego? (building verification survey), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
11. When do you need a survey for an ADU in San Diego? (price table), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
12. When do you need a survey for an ADU in San Diego? (what drives the price), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
13. When do you need a survey for an ADU in San Diego? (combined price), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
14. When do you need a survey for an ADU in San Diego? (timing), SnapADU (San Diego ADU builder). Facts checked 2026-10-10
15. Why a land survey matters in a Beverly Hills or Los Angeles real estate transaction, Christophe Choo (Beverly Hills real estate agent). Facts checked 2026-10-10
16. Accessory Dwelling Unit Handbook (March 2026): predevelopment costs, California Department of Housing and Community Development. Facts checked 2026-10-10
17. Professional Land Surveyors’ Act (2026), Business and Professions Code section 8726, Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). Facts checked 2026-10-10
18. Professional Land Surveyors’ Act (2026), Business and Professions Code section 8725, Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). Facts checked 2026-10-10
19. Professional Land Surveyors’ Act (2026), Business and Professions Code section 8762(b), Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). Facts checked 2026-10-10
20. Professional Land Surveyors’ Act (2026), Business and Professions Code section 8762(b)(2), Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG). Facts checked 2026-10-10
21. LA County Owned Assessor Parcels: a discussion of parcel accuracy, Los Angeles County (Assessor parcel layer description, LA County ArcGIS Online). Facts checked 2026-10-10
22. LA County Owned Assessor Parcels: accuracy, from a former Chief Cadastral Engineer of Assessor Mapping and GIS Services, Los Angeles County (Assessor parcel layer description, LA County ArcGIS Online). Facts checked 2026-10-10
23. Land Records Information: Records of Survey, Los Angeles County Public Works. Facts checked 2026-10-10
24. Land Records Information: Tract Maps, Los Angeles County Public Works. Facts checked 2026-10-10

Greenlight is not a contractor, architect or engineer, and this is not legal advice. Rules change; every fact here shows the date we last checked it.