Attached ADU Home Addition in Palo Alto
A new attached living unit built onto your existing home, matched to its architecture and structure.
A New Unit Built Onto Your Existing Home
An attached ADU shares a wall with your main house but functions as a fully independent unit — its own kitchen, bathroom, and entrance, while tying structurally and architecturally into your existing home. It is a strong option when a lot has limited backyard space for a fully detached structure but room to expand the building footprint.
We design the addition to match your home's roofline, siding, and window style so it reads as part of the original house rather than a bolted-on box, which matters both for Palo Alto design review and for resale value.
- Shares a structural wall with the main house, functions as an independent unit
- Architectural matching to existing roofline, siding, and windows
- Often more buildable square footage than backyard setbacks allow for a detached unit
- Full structural engineering for the tie-in to your existing foundation and framing
Frequently Asked Questions
How is an attached ADU different from a home addition?
An attached ADU has its own kitchen, bathroom, and separate entrance, and functions as an independent dwelling unit — a standard home addition just expands your existing living space with no separate unit created.
Will the addition match my house?
Yes — we design attached ADUs to match your home's existing roofline, siding, trim, and window style so the addition looks original to the house, not added on.
How much does an attached ADU cost?
Attached ADUs typically run $150,000 to $300,000+ depending on size and how much of the existing structure needs modification. We give a firm quote after a site visit.
Does an attached ADU need its own foundation?
Usually yes, tied structurally into your existing foundation — our structural engineer designs the connection so both structures perform correctly together.