Room Additions & ADU

Buildda Home Addition Process

Home additions in LA run $50,000-$700,000 depending on scope; permit approval alone takes 4-12 weeks before the foundation goes in. The process below covers design, structural engineering, permits, foundation, framing, MEP rough-in, finishes, and final inspection.

Step-by-Step Timeline

Room Additions & Home Extensions

Expand Your Living Space

Room additions in LA run $50,000-$100,000 for a single-room bump-out (200-300 sq ft), $120,000-$250,000 for a full ADU or large room addition with bathroom, and $350,000-$700,000 for second-story additions or major footprint expansions. Most projects span 4-9 months from contract signing to final inspection: 4-12 weeks for plan-check approval, then 3-6 months of on-site construction depending on scope.

Room additions in LA run $50,000-$700,000 depending on size and path. Permit approval alone takes 4-12 weeks; total project timeline is typically 3-6 months. ADUs trigger additional inspections (structural, electrical, plumbing, mechanical, energy) so they typically run on the longer end. Setbacks vary by city and zone; most front setbacks are 15-25 feet, side 3-5 feet, rear 10-20 feet. ADUs often have reduced setbacks per California state law (SB 9, AB 2221). Cost variance comes from foundation type (slab-on-grade is cheapest; raised foundation with crawlspace adds $5,000-$15,000), addition path (traditional addition vs. ADU or JADU under California AB 68/881 - ADU rules are more permissive on setback and height in most LA-area cities), single-story vs. two-story (going up is cheaper per square foot than going out, but only if the existing foundation can take the load), match-to-existing requirements (matching stucco color and texture, matching roofline, matching window style - labor-intensive details that determine whether the addition reads as one structure with the original or as a tacked-on extension), and permit + plan-check timeline. We coordinate the design team, structural engineer, city corrections, and the trades under license #1131088. 2-year workmanship warranty on the build.

Pricing Tiers

Pricing reflects typical projects in the Los Angeles area as of 2026. Actual quotes vary by site conditions, material lead times, permit requirements, access constraints, and the scope of any structural or substrate repairs uncovered during demolition. We provide a written, itemized estimate only after an on-site walkthrough. License #1131088, 2-year workmanship warranty on every project, in writing.

All prices are estimates. Actual costs vary based on project scope, site conditions, material selections, and permit requirements. Contact us for a personalized quote.