Building an Attached ADU in Redwood City, San Mateo County
An attached ADU in Redwood City borrows one wall from your existing house and turns the rest into a separate, legal home — its own entrance, kitchen and bath. We're a Sacramento design-build contractor, license #1119373, about two hours north. That distance is the first honest thing on this page: we extend down to Redwood City for owners who want our craftsmanship and value, or for projects big enough to earn the drive. What follows is how we think about attached units here, where the Peninsula's faults, terrain and slow permitting change the math, and where it gets harder than the brochure says.
What "attached" actually buys you
The word attached carries the whole concept. Your new unit shares precisely one wall with your existing Redwood City house and is otherwise a complete, independent home — a private door off the side or rear, a real kitchen with its own range and sink, a full bath, and a bedroom a tenant reaches without stepping into your space. That single shared wall is the only thing tethering the two homes together. Everything else stands on its own.
That one connection is why people pick attached over detached on the Peninsula. You're not setting a freestanding cottage at the back of a high-value lot and trenching utilities the length of the parcel to reach it. You grow off the house already standing, leaning on the foundation, panel and water line already there. On a Redwood City lot — tight, expensive, sometimes on a hillside grade — that sidesteps a fair amount of the site's difficulty before you've poured a thing.