ADU Utilities and Site Work in Los Angeles

Two similar ADUs can cost very different amounts because of work outside the walls. A backyard unit may need long trenches or a power-panel change. It may also need sewer review, grading, retaining walls or drainage. A narrow side yard can force workers to carry materials by hand.

Create one current-services record

Document the items below.

• electric utility, meter, service rating and panel location;
• available panel details and planned ADU loads;
• water utility, meter and service details;
• sewer location, cleanouts, route and elevation details;
• gas service if it is part of the design;
• communications and address rules;
• visible drainage paths and low points;
• known easements and overhead/underground lines; and
• the route from street to planned unit.

Mark facts as verified, observed or assumed. Do not let an assumption become a fixed-price exclusion silently.

Electrical planning

For the City of Los Angeles path shown, LADWP’s meter-spot guidance explains how it checks the panel location. It gives a typical 5–15-business-day window for a visit. New-build work goes to the LADWP Connection Center. Some panel plans need more service details.

A meter spot is not a full power design or price. Ask who checks service capacity, transformer or line work and trenches. Add the meter plan, panels, grounding, temporary power and utility fees.

Other cities may use Southern California Edison or city utilities. Use the address-specific company.

Water service

LADWP’s water installation page asks for the address, parcel number, service size and use. It says staff normally contacts the applicant within 3–5 business days with a Cost Letter.

The same page lists a typical 100 days from start to finish for small service work. It lists 140 days for large service work. Rules, permits and crew schedules can change those times. Main-line work can add time. Other fees may cover public systems, fire hydrants and street repairs.

Use these figures as planning signals only. Confirm the actual project and current utility instructions.

Sewer and plumbing route

Ask for the connection point, route length, slope, cleanouts and trench depth. Include repairs after the work. State whether waste will flow by gravity or use another method. Name who checks the plan.

For a garage conversion, include slab trenching and patching. For a detached unit, include work between the building and connection point, plus any work in the main building or public way.

Drainage and grading

The site plan should show current and proposed ground levels. Add roof drainage, paved areas and discharge points. Do not solve a placement problem by sending water toward another building or lot.

Ask whether civil, grading, retaining or geotechnical work is included or separately required. Mark export, import, erosion protection and repairs after the work.

Construction access and logistics

Measure gates, side yards, overhead space and slopes. Mark areas for materials, trash bins, pumps, concrete work and crew access. Note parking, street or neighbor limits that need permits or planning.

Ask the builder to explain the construction method it priced. If its estimate assumes machine access that the site does not have, the total is not reliable.

Quote schedule for external work

Do not accept “standard site work included” without quantities or boundaries.

How utilities affect cost and timeline

Utility requests can move forward during design. The schedule must show what each step waits for. A permit-ready building plan does not mean public or field work is ready.

The timeline guide separates company-controlled work from agency and owner choices. The cost guide places utility charges and construction in distinct rows.

When should a specialist be involved?

Bring in the right designer, engineer or utility contact when needed. The project may also need a plumber, electrician, surveyor or soil expert. A general site visit is not approval from every expert.

Preserve evidence before trenches are closed

Agree on inspections and records before digging begins. Take photos before trenches are filled. Show routes, depths, bedding, joints, cleanouts, valves and space between lines. Tie measurements to fixed points on the site. Keep test results and public sign-offs that apply.

Update the site record when the installed route differs from the plan. Good records help with future repairs and later work on the property. Include tests and final records in the Los Angeles, California ADU cost guide. Do not treat them as an assumed extra.