2.5) Utilities and infrastructure: plan early, avoid expensive surprises
Utility planning is one of the most underestimated parts of ADU budgeting. Before you finalize a layout, understand:
- Where water and sewer connections are located on the property
- Whether the electrical panel has capacity for the new unit
- How far trenching may need to run (distance matters)
- Whether you want separate metering (project-specific)
- HVAC approach: mini-split systems are common in smaller units, but the right choice depends on layout and comfort goals
San Diego tip: Even with a mild climate, a well-insulated ADU with good windows will feel dramatically more comfortable (and quieter). Energy-efficient design is not only about bills; it is about livability.