Room Addition Cost in Los Angeles, CA (2026)
A room addition in Los Angeles costs $300–$600 per sq ft, with a typical mid-size room addition running $110k–$220k. Small projects start around $50k; large or high-end work can reach $400k or more.
Costs in Los Angeles sit near the LA County baseline, shaped by LADBS permit complexity, dense urban logistics, and elevated trade-labor rates.
Room Addition Cost by Size in Los Angeles
Totals adjusted for the Los Angeles market (1.00× LA County baseline). Ranges include labor, materials, permits, and contractor overhead.
| Size | Type | Range | Low | High |
|---|---|---|---|---|
| Small | Bump-out / single room | 150–250 sq ft | $50k | $110k |
| Medium | Suite addition | 300–500 sq ft | $110k | $220k |
| Large | Second story / multi-room | 600+ sq ft | $200k | $400k |
What Affects Room Addition Cost in Los Angeles?
- Foundation: extending a slab or pouring new caissons on a hillside lot can add $15k–$60k before framing.
- Roofline integration: matching pitch, ridge, and shingles across the old and new structure adds 10–20% to roofing scope.
- MEP extension: rerouting HVAC, panel upgrades, and new plumbing branches typically add $12k–$30k.
- LADBS permits: room additions trigger full plan check, energy calcs, and often a soils report — 6–12 weeks of permitting.
- Soil & hillside: LA hillside parcels require geotechnical reports and may need grading permits.
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Get MatchedRoom Addition Sub-Type Comparisons
Bedroom Addition vs Master Suite Addition
A standard bedroom addition runs $50k–$110k; a master suite (bedroom + bath + walk-in closet) doubles the plumbing scope and lands at $110k–$220k.
Second Story Addition vs Sunroom Addition
Second-story additions require foundation reinforcement and full re-roof at $200k–$400k; sunrooms (prefab or stick-built) skip much of the structural work at $30k–$90k.
How to Get the Best Price on a Room Addition in Los Angeles
- Order a soils report before bidding — LA contractors price hillside risk conservatively, and a clean report can drop bids 10%.
- Get 3 bids on a complete structural plan set; vague plans produce $50k+ pricing variance.
- Phase the addition shell + interior separately if cash flow is tight.
- Bid in winter; LA additions are seasonal and contractors discount 5–8% Nov–Feb.
Frequently Asked Questions — Room Addition in Los Angeles
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