Attached ADU Design — Add a Private Living Space Connected to Your Home
An attached accessory dwelling unit is a self-contained living space that shares at least one wall with your primary residence. It has its own entrance, kitchen, bathroom, and living area but is physically connected to your main house — making it a practical choice when backyard space is limited or when you want family members close by.
Uni Construction has designed hundreds of attached ADUs across Los Angeles County. We specialize in designing additions that blend with your home’s existing architecture while meeting every structural, zoning, and code requirement.
Why Homeowners Choose Attached ADUs
Lower construction cost than detached — shared walls reduce foundation, roofing, and framing expenses
Ideal for multigenerational living — close proximity with full privacy
Shared utilities can simplify connections and reduce infrastructure costs
Works well on smaller lots where setbacks limit detached construction
Increases property value while expanding your home’s overall footprint
What We Design
Our attached ADU design package includes every document required for permit approval:
Integration analysis: We study your home’s existing structure, foundation, and roof to determine the best connection point
Architectural plans: Floor plans, building sections, and elevations showing how the ADU integrates with the existing home
Structural engineering: Connection details, load calculations, and reinforcement plans stamped by a licensed engineer
MEP design: Plumbing, electrical, and HVAC layouts — tied into or separated from existing systems based on what’s most efficient
Title 24 & CALGreen: Energy compliance and green building reports
Size & Zoning Quick Reference
California law allows attached ADUs up to 850 square feet for a studio or one-bedroom, and up to 1,000 square feet for two or more bedrooms. Attached ADUs cannot exceed 50% of the existing home’s floor area. Height limits are up to 25 feet or the height of the primary dwelling, whichever is lower. No additional parking is required if the property is within half a mile of public transit.
Common Attached ADU Configurations
Side addition: Extends off the side of your home with a separate entrance from the driveway or side yard
Rear addition: Built off the back of the house, often opening to the backyard
Second-story addition: Stacks the ADU above the existing home or garage — preserves your entire yard
Each configuration has different structural and cost implications. We walk you through the trade-offs during the feasibility stage so you can make an informed decision.
Wondering if an attached ADU makes sense for your home? Get a free feasibility report and find out what’s possible on your property.
