Location: Twain Harte, CA

what we offer

5-Star & Award-Winning ADU Builder & Architect in Tuolumne County

In Twain Harte, CA, Mi-Wuk Village, Pinecrest, Soulsbyville, Tuolumne, Sonora, and Jamestown., an accessory dwelling unit (ADU) is a sought-after home construction project for its ability to add valuable living space to your property. Cornerstone Construction is a Twain Harte ADU contractor and architect capable of managing the entire home improvement project, from ADU design to construction.


There are various options available for the types of ADUs suitable for your home. Cornerstone Construction can design and construct an ADU from the ground up, whether attached or detached, as well as handle ADU garage conversions.

GE IN TOUCH

Streamlined Permitting and Zoning Solutions

Your Trusted Twain Harte ADU Contractor.

Moreover, we are well-versed in permits, state law requirements, and ADU ordinances issued by the city of Twain Harte and surrounding areas. We take charge of the processes necessary to obtain the proper building and zoning documentation, ensuring a hassle-free experience for you.


Cornerstone Construction, as a Twain Harte ADU contractor and ADU construction company, is dedicated to expanding your home's space and value to better suit your needs.

Accessory Dwelling Unit vs. Room Addition.

ADU homes, also known as granny flats or mother-in-law houses, are new structures that can be attached to or detached from the existing residence. They function as standalone homes with their own kitchen, bathroom, bedroom, and living space, serving purposes such as guest houses, rental units, separate living or workspace, or pool houses.


On the other hand, a room addition involves expanding the main structure of a single-family home for additional square footage. These projects typically aim to enlarge existing rooms such as kitchens, family rooms, or master bedrooms, add new bedrooms and/or bathrooms, or even construct a second or third story.

GET IN TOUCH

Twain Harte, CA ADU Services

Cornerstone Construction brings 18 years of experience in new construction and renovations in Twain Harte, CA. As a full-service ADU contractor, we prioritize high-quality craftsmanship and unparalleled customer service. Your satisfaction and comfort are our top priorities.


Cornerstone Construction is equipped to oversee every aspect of your Twain Harte ADU construction, including garage conversions. While our expertise covers design, architecture, and engineering, we are also open to collaborating with any independent architect, designer, or engineer you choose to hire.

  • Architectural Planning
  • Open Floor Plans
  • Design & Construction
  • Engineering
  • Permit Acquisition
  • Kitchen Construction
  • Bathroom Construction
  • Demolition
  • Structural Improvements
  • Electrical & Lighting
  • Title 24 Energy Efficiency
  • HVAC
  • Roofing
  • Tilework
  • Plumbing
  • Flooring
  • Painting
  • Windows
  • Doors
  • Solar Panels

Less Time & Money

Choose from a selection of gorgeous ADU plans pre-approved by the city of Twain Harte, CA. These detached, flexible designs shorten the permit process by weeks! Square feet, and amenities will range and are designed to suit most residential properties and range from studios to 2-story ADU plans.


These ADU designs and floor plans offer exciting features, including rooftop decks, exterior staircases, expansive patios, abundant natural light, and stunning architectural elements.

How It Works

Cornerstone Construction can help you select the right plan for your property and your needs. Simply contact us for a site visit and a free estimate. We then manage the plan submission process for you. As a one-stop-shop, we also build your ADU from the ground up, managing every element of construction for seamless, expedited project completion.

Contact us today

Not seeing a plan that’s right for you?

Our architectural team can design a custom ADU with an interior and exterior that has all the features and aesthetics you want.

CALL US NOW!

Areas We Service

At Cornerstone Construction, we're proud to extend our services to the following areas:

  • Twain Harte, CA
  • Mi-Wuk Village, CA
  • Pinecrest, CA
  • Soulsbyville, CA
  • Tuolumne, CA
  • Sonora, CA
  • Jamestown, CA
  • Groveland, CA
  • Columbia, CA
  • Chinese Camp, CA
  • East Sonora, CA
  • Tuttletown, CA
  • Cold Springs, CA
  • Phoenix Lake, CA
  • Long Barn, CA
  • Strawberry, CA
  • Cedar Ridge, CA
  • Dardanelle, CA
  • Mono Vista, CA
  • Sierra Village, CA

Contact us today to bring your vision to life in these beautiful communities.

(209) 352-3354

GET in touch

Request For A Quote

No matter the scope or scale of your project, Cornerstone Construction is committed to exceeding your expectations and bringing your vision to life.

GET a QUOTE

Contact Us

Share by: