A second story addition is one of the most ambitious and highest-value construction projects a Los Angeles homeowner can undertake. Adding a full or partial second story to a single-story home dramatically increases livable square footage without consuming the rear yard. This guide breaks down second story addition costs in Los Angeles for 2026 with real price ranges from completed APLA projects. APLA Construction (CA Lic #1136359) builds second story additions throughout Greater Los Angeles.
Cost per square foot for a second story addition in Los Angeles runs $280–$450/sq ft finished, depending on structural complexity, existing foundation capacity, and finish level.
The existing single-story foundation must support the additional weight of a second story. Older LA homes (pre-1980) often require foundation upgrades — adding concrete piers, widening footings, or installing new grade beams. Foundation work adds $15,000–$60,000 to most second-story addition projects.
The existing first-floor walls and framing must be evaluated for vertical load capacity. Many post-war LA homes need first-floor shear wall upgrades, new point loads (posts), and beam reinforcement before a second story can be added. First-floor reinforcement typically adds $20,000–$45,000.
A new staircase from the first to second floor is required. Staircase cost depends on design and materials: a standard code-compliant staircase with oak or LVP treads runs $12,000–$22,000. A custom staircase with open risers, steel, or custom railing runs $22,000–$45,000+.
Adding a second story means replacing the existing roof. The new roof is larger, typically more complex (new ridgeline, hips, valleys), and must meet current Title 24 and fire hardening requirements (Class A on fire zone properties). Roofing on a second-story addition typically costs $18,000–$45,000 depending on the roof area and material.
The second story needs its own mechanical, electrical, and plumbing systems — HVAC zones, new electrical circuits and panel capacity, plumbing if bathrooms are added. MEP systems for a 1,000 sq ft second story typically cost $35,000–$65,000.
| Item | Cost |
| Foundation assessment and reinforcement | $28,000 |
| First-floor structural upgrades | $24,000 |
| Second-story framing | $68,000 |
| Roofing (new full roof) | $32,000 |
| Windows and exterior | $28,000 |
| Staircase | $18,000 |
| MEP (2 baths, HVAC zone, electrical) | $58,000 |
| Insulation and drywall | $32,000 |
| Flooring (3 bedrooms, hallway) | $24,000 |
| Interior doors, trim, paint | $18,000 |
| Bathrooms (2 full baths) | $72,000 |
| Design and engineering | $28,000 |
| LADBS permits | $14,500 |
| General contractor overhead and profit (20%) | $89,000 |
| Total | $533,500 |
Second story additions require a comprehensive LADBS permit package: building, structural, electrical, plumbing, and mechanical permits. Structural engineering is required. Plan check at LADBS takes 8–16 weeks for second-story additions. APLA manages the full permit process including engineering coordination, LADBS submissions, plan check responses, and all inspections.
A partial second story addition (400–800 sq ft) in Los Angeles costs $210,000–$380,000. A full second story (1,000–1,500 sq ft) costs $380,000–$680,000. Cost per sq ft runs $280–$450 depending on scope and finishes.
A second story addition in Los Angeles takes 16–24 months total from design start through Certificate of Occupancy. LADBS permit processing takes 8–16 weeks. Construction takes 9–16 months depending on scope.
Usually yes for homes built before 1980. APLA conducts a structural assessment and engineering review of the existing foundation and first-floor framing before finalizing any second-story addition design. Foundation and structural reinforcement adds $20,000–$60,000 to the project but is non-negotiable for code compliance and long-term structural integrity.
In most Los Angeles markets in 2026, yes. Moving transaction costs (realtor fees, transfer taxes, loan costs) on a $1.5M+ home run $100,000–$150,000. A second story addition at $400,000–$600,000 adds permanent equity and avoids the transaction costs and disruption of moving. In neighborhoods like Sherman Oaks, Encino, Woodland Hills, and Pasadena, second-story additions are a common and financially sound alternative to moving.
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Email: info@aplaconstruction.com
CA General Contractor License #1136359
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