Room Addition Cost Brentwood CA 2026 — Full Price Guide

Room Addition Cost Guide for Brentwood, CA — 2026

Brentwood room additions operate in one of Los Angeles’s most consistently premium residential markets — home values of $3M–$12M+, a buyer pool of established wealth, and architectural expectations that bridge the gap between the California casual and the genuinely luxurious. Brentwood additions must be seamlessly integrated with the existing architecture, finished at the highest quality tier, and designed to add genuine value in a market where buyers are sophisticated and quality is the baseline. APLA Construction (CA Lic #1136359) handles room additions throughout Brentwood, managing LADBS permits and all construction under one contract.

Brentwood Room Addition Costs by Scope (2026)

Scope 1: Primary Suite ($245,000–$445,000)

What you get: Primary bedroom (200–310 sq ft) with attached primary bathroom (80–140 sq ft), walk-in closet with custom organization, and sitting area. Custom millwork throughout. Radiant heated floor in the bathroom. Natural stone tile. At Brentwood values of $3M–$6M, the primary suite must meet the highest quality standard — semi-custom finishes are not competitive in this market.

Scope 2: Multi-Room Addition ($440,000–$780,000)

What you get: Multi-room addition encompassing a full primary suite wing plus additional bedroom, home office, or family room extension. 700–1,200 sq ft of new living space at Brentwood’s premium finish standard. LADBS structural plan check plus hillside review if applicable. For Brentwood homes at $5M–$10M where the addition is a comprehensive improvement to the living program.

Scope 3: Estate Addition or Second Story ($720,000–$1,800,000+)

What you get: Major architectural addition — full second story or multi-wing estate-level addition. Custom design by architect. European-level finishes. For Brentwood estates at $8M–$20M+. APLA works alongside architects and designers for additions at this tier.

LADBS and Hillside Permitting in Brentwood

Brentwood is in the City of Los Angeles — all permits go through LADBS. Many Brentwood properties are in the hillside construction area (properties north of San Vicente, toward the Santa Monica Mountains). Hillside additions require: soils report, hillside structural engineering, and potential additional LADBS HCRA review. APLA evaluates hillside requirements for every Brentwood addition project.

Frequently Asked Questions — Room Addition Cost Brentwood CA

How much does a room addition cost in Brentwood in 2026?

Primary suite: $245,000–$445,000. Multi-room addition: $440,000–$780,000. Estate addition: $720,000–$1,800,000+. Brentwood addition costs are in the top tier of the LA market — comparable to Pacific Palisades and Santa Monica, below Beverly Hills and Bel Air.

How long does a room addition take in Brentwood?

Primary suite: 10–17 months (includes LADBS plan check of 8–12 weeks plus construction). Multi-room: 14–24 months. Estate-scale: 20–36 months. Hillside properties add 4–8 weeks for soils review and HCRA review.

Does APLA do room additions in Brentwood?

Yes. APLA (CA Lic #1136359) handles room additions in Brentwood, managing hillside LADBS requirements and all construction. Call (818) 818-4419 for a free in-home estimate.

Get a Free Estimate for Your Brentwood Room Addition

Call: (818) 818-4419
Email: info@aplaconstruction.com
CA General Contractor License #1136359

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