Short answer. A home addition in Los Angeles in 2026 runs $350 to $650 per sq ft. Typical ranges: 300 sq ft addition $105,000 to $200,000. 500 sq ft master suite $175,000 to $325,000. 800 sq ft family room expansion $280,000 to $520,000. Design, permits, foundation, frame, finishes, and trade work are included.
2026 pricing by size and use
| Type | Size | Cost |
|---|---|---|
| Bedroom addition | 200 to 300 sq ft | $70,000 to $195,000 |
| Family room or great room | 300 to 500 sq ft | $105,000 to $325,000 |
| Master suite (bedroom + bath + closet) | 400 to 700 sq ft | $160,000 to $455,000 |
| Kitchen expansion | 200 to 400 sq ft | $120,000 to $300,000 (kitchen finishes add cost) |
| Full wing addition (multiple rooms) | 700 to 1,200 sq ft | $280,000 to $780,000 |
What is included in a home addition price
- Design and engineering.
- Permit fees and plan check.
- Site prep and foundation.
- Framing for walls, floor (if needed), and roof.
- Exterior envelope (siding or stucco, windows, doors, roofing).
- HVAC tie-in or new system.
- Electrical and plumbing rough and finish.
- Insulation per Title 24.
- Drywall, flooring, paint, trim.
- Finish hardware and fixtures.
- Final cleanup and inspection.
What drives cost up
- Sloped or hillside lots (foundation cost can double).
- HPOZ overlay requiring historic finish match.
- Coastal Commission review.
- Premium finishes (custom millwork, stone, high-end fixtures).
- Mechanical upgrades to the existing home (panel upgrade, HVAC replacement).
- Demolition of existing walls or roof sections.
- Foundation upgrades to existing home where the addition ties in.
How to keep cost in control
- Design for the existing roofline. Addition shapes that tie into existing roof valleys cost more than simple extensions.
- Avoid moving plumbing fixtures or kitchen sinks more than necessary.
- Use the existing electrical panel if it has capacity.
- Choose finishes that match the existing home rather than a new design language.
- Get three bids on identical scope. Compare line by line.
- Hold 15 to 20 percent contingency for hidden conditions.
Addition vs ADU
A 600 sq ft detached ADU runs $200,000 to $400,000. A 600 sq ft addition runs $210,000 to $400,000. ADUs offer rental income potential and an easier permit path under state law. Additions extend the existing home directly, with shared roofline, walls, and HVAC. The right choice depends on use case.
For ADU comparison, see ADU cost Los Angeles. For second story options, read second story addition cost. For services, see our room addition page.
