ADU floor plans · 800 sq ft
800 sq ft is the most common ADU size built in California — large enough for a real 1-bedroom or a tight 2-bedroom, small enough to permit by-right almost anywhere. These four layouts cover the four ways most homeowners and builders actually use this footprint, with the trade-offs each layout makes.
Why 800 sq ft is the workhorse size: It's the largest footprint that's both impact-fee-exempt (in California) and permitted by-right in nearly every jurisdiction. You get a full kitchen with full-size appliances, a real bathroom, and either a generous 1BR or a tight-but-real 2BR. Most owner-occupiers and most rental-focused builders converge on this size.
The four layouts below cover the two main 1BR strategies (open vs split) and the two main 2BR strategies (side-by-side vs kitchen-spine). The choice depends on lot orientation, whether you're renting or hosting family, and how much you cook.
1 BR · 1 bath · Est. $200K – $260K
Best for: Hosts or guests. Generous bedroom suite plus a big open kitchen/living for entertaining.
1 BR · 1 bath · Est. $210K – $270K
Best for: Long-term renters who want bedroom privacy from the living/kitchen — bedroom and main areas at opposite ends of the unit.
2 BR · 1 bath · Est. $230K – $300K
Best for: Roommates or a small family. Two bedrooms share a wall, kitchen and living wrap the other half.
2 BR · 1 bath · Est. $240K – $320K
Best for: Lots where bedrooms at opposite ends maximize privacy — kitchen runs as a central spine connecting them.
What's the most popular ADU size?
800 sq ft. Industry surveys consistently show ~40-50% of newly-built California ADUs land between 700 and 900 sq ft. It's the sweet spot between by-right permitting, impact-fee exemption, and enough space for real 1- or 2-bedroom living.
How much does an 800 sq ft ADU cost?
Typically $200,000–$320,000 all-in. Cost per square foot ($250–$400) is lower than smaller ADUs because fixed costs (permits, utility hookups) spread across more square footage.
Can I fit a 2-bedroom in 800 sq ft?
Yes, but each bedroom will be 110–140 sq ft (typical apartment scale, not suburban-house scale). The 'side-by-side' and 'linear kitchen' layouts below show two realistic 2BR arrangements at this footprint.
Will an 800 sq ft ADU rent for more than a 400 sq ft?
Yes — usually $400–$800/month more in most California metros. The marginal cost of building the extra 400 sq ft is typically $80K–$140K, which pays back the extra rent in 12–25 years depending on local rents.
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