800 sq ft ADU Cost in California (2026)

An 800 sq ft ADU is one of the most popular choices in California, often designed as a comfortable two-bedroom unit. It provides the space needed for a small family, long-term rental, or multi-generational living while keeping overall construction costs below those of full-size homes.

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Price Range & Line Items

Here’s how the construction cost for an 800-square-foot ADU typically breaks down:

Category	Estimated Cost Range
Construction (hard)	$165,000 – $230,000
Site prep & utilities	$18,000 – $40,000
Design & engineering	$10,000 – $20,000
Permits & city fees	$7,000 – $15,000
Total	$190,000 – $300,000+

Most 800 SF ADUs fall in the $200k–$240k range, depending on site work, city fees, and finish level.

Construction covers framing, roofing, plumbing, electrical, insulation, and interior finishes.
Site prep includes grading, foundation adjustments, and trenching for utilities.
Design & engineering includes plans, structural review, and Title 24 energy compliance.
Permits & fees vary widely by jurisdiction, with larger cities like Los Angeles typically at the higher end.

💡 Tip: With room for two bedrooms, an 800-square-foot ADU offers one of the best floor plan options for maximizing both livability and rental income.

Project Timeline

Typical schedules for an 800 sq ft ADU in California look like this:

Design & permitting (3–4 months): Includes floor plans, structural engineering, Title 24, and city review cycles.
Construction (6–8 months): Site preparation, foundation, framing, utility connections, and full interior/exterior finishes.
Total duration (9–12 months): From first drawings to a move-in ready unit.

💡 Ataman Studio oversees the process — from design and permits to construction coordination — ensuring your project stays on track and within 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 800 sq ft ADU?

Get Your Estimate

An 800-square-foot ADU is large enough for a two-bedroom layout, making it one of the most versatile and cost-effective mid-size options. Whether for family or rental income, this size delivers excellent value. Request your tailored estimate today.