ADU Floor Plans 400 Sq ft
A 400 ft² studio ADU is the fastest to permit in many cities and the cheapest per foot to build.
Plan specs
- Total area
- 400 ft²
- Bedrooms
- Studio
- Bathrooms
- 1
Generated to scale — every room dimension is real and the areas sum to the total.
An ADU has to fit a full home — kitchen, bath, living, and sleeping — into a footprint your lot and local code will allow, often 400 to 1,000 ft². That makes an accurate plan essential: a few misjudged feet can be the difference between a comfortable rental and a layout that never quite works.
Designing a 400 ft² adu plan
- Check your local max ADU size and setbacks before choosing square footage.
- A 600 ft² one-bed is the sweet spot for rentability and cost.
- Put the kitchen and bath back-to-back to share a plumbing wall.