600 sq ft ADU Cost in California (2026)

A 600 sq ft ADU is one of the most popular choices for homeowners. It provides enough space for a functional one-bedroom layout with a living room and full kitchen, making it ideal for long-term rentals or extended family living.

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Price Range & Line Items

Here’s how the budget for a 600 SF ADU typically breaks down:

Category	Estimated Cost Range
Construction (hard)	$135,000 – $190,000
Site prep & utilities	$15,000 – $35,000
Design & engineering	$10,000 – $18,000
Permits & city fees	$7,000 – $13,000
Total	$160,000 – $250,000+

Most 600 sq ft ADUs finish in the $180k–$210k range, depending on site conditions and finish level.

Construction includes all major building work — foundation, framing, roofing, electrical, plumbing, insulation, and interiors.
Site prep covers grading, foundation adjustments, and trenching for utilities.
Design & engineering provides architectural plans, structural calculations, and Title 24 energy compliance.
Permits & fees vary depending on city rules and requirements.

💡 Tip: A 600 sq ft ADU is often the “sweet spot” for rental units — large enough to attract long-term tenants but still cost-efficient to build.

Project Timeline

A 600 Square-Foot ADU takes slightly longer than micro-units but is still faster than mid- or large-scale builds. Typical timelines in California:

Design & permitting (3–4 months): Architectural plans, engineering, energy compliance, and city review.
Construction (5–7 months): Site prep, foundation, framing, utility connections, and finishes.
Total duration (8–11 months): From first drawings to move-in ready.

💡 Ataman Studio manages the full process — from plans and permits to construction oversight — helping keep your project on schedule and budget.

Compare ADU Costs by Size

200 sq ft 300 sq ft 400 sq ft 500 sq ft 600 sq ft 700 sq ft 800 sq ft 900 sq ft 1000 sq ft 1100 sq ft 1200 sq ft

Ready to Build a 600 SF ADU?

Get Your Estimate

A 600 sq ft ADU is a practical, flexible size — perfect for rentals, in-law living, or guest housing. With room for a one-bedroom layout, it’s one of the most versatile ADU options in California. Request your custom estimate today.