ADU Contractors
Silicon Valley

M&R Quality Construction builds Accessory Dwelling Units throughout Santa Clara County — from permitted plans to Certificate of Occupancy. 40+ years of California construction experience. Lic. #734451.

CA Lic. #734451
40+ Years Experience
Santa Clara County
Permit-to-CO Service
Fixed-Price Contracts

Add Living Space.
Add Property Value.

An Accessory Dwelling Unit (ADU) is a secondary housing unit on a single-family or multifamily residential lot. California law now makes it easier than ever to build one — and Santa Clara County cities like San Jose, Saratoga, Cupertino, and Los Gatos have streamlined their local approval processes.

ADUs are used for multigenerational living (aging parents, adult children), long-term rental income, home office space, or guest quarters. A well-built ADU in Silicon Valley typically adds $200,000–$500,000 to your property's market value.

As licensed ADU contractors serving Santa Clara County since 1985, M&R Quality Construction manages every phase: site feasibility, architectural design, permit submittal, construction, and final inspection.

Detached ADU

A fully independent structure built on the same lot as your primary home. Maximum privacy, rental income potential, and property value increase.

Attached ADU

An addition connected to your existing home — ideal for multigenerational living or maximizing lot coverage without a separate foundation.

Garage Conversion

Convert an existing attached or detached garage into a livable ADU. One of the most cost-effective options with minimal new construction required.

Junior ADU (JADU)

Up to 500 sq ft carved out of your existing home's footprint. Requires an efficiency kitchen and separate entrance — streamlined permitting under California law.

From Permit to
Certificate of Occupancy

01

Free Site Consultation

We visit your property, assess zoning, setbacks, utility connections, and lot coverage to determine what ADU types are feasible and what the permit path looks like.

02

Design & Permit Plans

Our team prepares architectural drawings and submits permit applications to your city or county. We handle all plan check responses and corrections.

03

Permit Approval

We track your permit through the approval process and coordinate with the building department. California SB 9 and ADU reform laws have significantly shortened timelines.

04

Site Preparation & Foundation

Grading, excavation, and foundation work — the most critical phase. Our crews set the grade beams and concrete to code, inspected and approved before framing begins.

05

Framing, MEP & Insulation

Structural framing, rough plumbing, electrical, and HVAC are installed and inspected. Insulation is installed to California Title 24 energy standards.

06

Finishes & Certificate of Occupancy

Drywall, flooring, cabinetry, fixtures, and exterior finishes are completed. Final inspections lead to your Certificate of Occupancy — your ADU is ready to use.

Active ADU Build

See Our ADU Under Construction

Follow along with a live ADU build — grade beams, concrete pour, retaining walls, and framing.

View ADU Build Gallery

The ADU Contractor
Santa Clara County Trusts

  • 40+ years of California construction experience
  • CA Contractor Lic. #734451 — fully licensed and insured
  • Deep knowledge of Santa Clara County ADU permit process
  • In-house design, permitting, and construction — one team, no handoffs
  • Transparent fixed-price contracts with no surprise change orders
  • Active ADU builds in San Jose, Saratoga, Cupertino, and Los Gatos

ADU Cost Estimates — Santa Clara County

Junior ADU (JADU)$60,000 – $120,000

Up to 500 sq ft, within existing home

Garage Conversion$80,000 – $160,000

Existing structure, minimal new foundation

Attached ADU$150,000 – $280,000

Addition to existing home

Detached ADU$220,000 – $420,000+

New standalone structure, 400–1,200 sq ft

Estimates include construction only. Permit fees, utility connections, design, and site-specific conditions vary. Contact us for a free site visit and detailed estimate.

Request a Free Estimate
San JoseSaratogaCupertinoSanta ClaraLos GatosCampbellSunnyvaleMountain ViewPalo AltoMilpitasLos AltosWillow GlenAlmaden ValleyEvergreen

Common Questions
About ADU Construction

Ready to Build Your ADU
in Santa Clara County?

We offer a free, no-obligation site visit and feasibility assessment for ADU projects throughout Silicon Valley. Call us or fill out the contact form and we'll be in touch within one business day.

CA Contractor Lic. #734451 · M&R Quality Construction, LLC · Silicon Valley, CA