One wall joins it,
a full second home on your Davis lot.

An attached ADU shares exactly one wall with your existing Davis house. That single wall is the whole difference between this and a freestanding cottage out near the back fence. Past it, the unit is a complete home — a private door off the side or rear, a real kitchen, a full bath, a bedroom nobody walks through your living room to reach. We like attached units in a town this flat and this bike-everything, where students and faculty will rent a quiet side unit fast. The trade is structural honesty. The new build ties into your roofline, your foundation and your existing wall, and on Yolo clay that tie-in wants real thought. Done right, you can't find the seam from the parkway.

Davis is its own incorporated city, so your permit files with the City of Davis — not Yolo County, and not a generic regional counter. Attached units get an extra look in plan check: reviewers study how the addition connects to your existing house, so your home's as-built condition matters more than it would for a detached job. Two Davis-specific layers ride along. The City stacks its green-building reach codes on top of CALGreen — leaning all-electric and solar-ready, stricter than the state baseline. And the tree ordinance means a protected tree near your build line pulls in an arborist report and a tree permit. State law keeps ADU review ministerial, so a complete set has to be issued. Clean attached submittals have been turning in roughly 4-6 weeks.