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ADU Construction

We design and build accessory dwelling units in San Jose and across the South Bay — detached backyard units, garage conversions and attached additions.

Most of the ADU calls we get start with a family situation rather than a floor plan. A parent is getting older and living alone forty minutes away. An adult son or daughter is working locally and cannot make the rent math work. A family wants everyone on one property without everyone in one kitchen. An ADU is one of the few ways left to add real living space to a lot in Santa Clara County, and California has made these units substantially easier to permit in recent years — cities have to follow the state rules on them.

The lots around here make every project its own problem. Older San Jose neighborhoods run long and narrow with a detached garage at the back of a shared driveway. Postwar tracts in Sunnyvale and Santa Clara have deep rear yards but a lot of underground utilities in the way. Ranch and Eichler-era homes in Palo Alto, Cupertino and Los Altos come with slab foundations and low rooflines that decide what an attached unit can look like. We walk the property first, talk through what actually fits, and tell you plainly when the idea you came in with is not the right one for that lot.

What’s included

A site walk covering setbacks, existing utilities, drainage, trees and equipment access — before any drawings start
Plans and engineering coordinated for submittal to your city or county building department
Permit submittal and follow-through on plan check comments, including revisions and resubmittals
Foundation, framing, roofing and exterior finishes matched to the main house so the unit does not read as an add-on
Full rough-in and finish for electrical, plumbing and mechanical, including any panel or service upgrade
Kitchen and bath build-out, including cabinets we build in our own shop rather than order in
Garage conversions — slab work, insulation, egress, replacing the door opening and reworking the roofline where needed
Insulation, drywall, flooring, trim, doors and hardware through final inspection and sign-off

Why R Twyns Construction

We are a family-run licensed general contracting and remodeling company (CSLB #896811), building in the South Bay since 2007. Tim Reynolds owns the company and his VP Ben runs the work, so the people who price your job are the people who are on it. The cabinets and finish carpentry come out of our own shop, which is what an older house needs when nothing in it is square. And we tell you what a job actually involves before you commit to it — the load-bearing wall, the drain line, the permit — rather than after the walls are open.

Common questions

Can I put an ADU on my lot?

That depends on the lot, the existing structures and the rules your city is applying right now. State law has opened this up considerably, but each city administers it through its own planning counter and the details change. We will not guess at it over the phone. We look at the property, then check the current requirements with the jurisdiction before you spend money on drawings.

Is converting the garage cheaper than building a detached unit?

Often, because the slab, walls and roof already exist. It is not automatic. Older South Bay garages were built as garages — the slab may sit too low, there may be no real footing under the walls, and the ceiling height may not work. We check those things before telling you it is the cheaper route. And you lose the garage, which matters more on a narrow lot with no street parking.

How long does the whole thing take?

A build has two clocks: ours and the city plan check. We can give you a realistic construction schedule for your specific project once the scope is set. We cannot tell you how long a plan check will run, and we will not pretend otherwise. Anyone quoting you a total timeline before the drawings exist is guessing.

Do you handle the permits, or is that on me?

We handle it. We prepare the submittal, take the plan check comments, revise and resubmit, and call inspections through to final. You are welcome to be involved as much as you want. What no contractor can do is promise you an approval — that decision belongs to the building department. Our license is CSLB #896811 if you want to check it before we pull anything in your name.

What is different about working with you?

We are a family-run company — Tim Reynolds owns it, his VP Ben runs the field side, and you deal with them directly. We build our own cabinets and do our own finish carpentry in-house instead of handing that off. On a small unit, where the kitchen and the built-ins are most of what you look at every day, that is the part that shows.

Serving the South Bay and the Peninsula

Ready when you are.

San Jose, Santa Clara, Palo Alto, Cupertino, Los Gatos and Sunnyvale — plus Mountain View, Redwood City, Campbell, Saratoga, Los Altos, Monte Sereno, Morgan Hill, Gilroy and Hollister, across Santa Clara, San Mateo, Alameda and San Benito counties.

Call (408) 313-6764 Request an Estimate

Mon–Fri 8:00–4:30 · CSLB #896811