Cornerstone Builders Inc

Cornerstone Builders Inc offers full-service ADU construction, including custom design, utility connections, and interior finishes. Specializing in detached ADUs, garage conversions, and JADUs, they use energy-efficient materials for functional, livable spaces.

Cornerstone Builders Inc – ADU Contractor in Beaverton, OR

About Cornerstone Builders Inc

ADU Services Offered by Cornerstone Builders Inc

Cornerstone Builders Inc handles the full scope of accessory dwelling unit projects, managing the key details that go into building a functional and well-finished living space. As an experienced ADU contractor, they work through each phase of the project with attention to the specific needs of the property and the homeowner's goals.

Custom Layout and Design Planning

Cornerstone Builders Inc develops ADU floor plans tailored to the individual project. Their approach focuses on making practical use of available space while balancing functionality and appeal. Whether the goal is a detached ADU, a garage conversion, or an in-law suite, the layout is planned to suit the intended use.

Utility Connections and Upgrades

As part of their ADU builder services, Cornerstone Builders Inc manages the installation and connection of plumbing, electrical, and HVAC systems. This includes any necessary upgrades to existing infrastructure to meet local requirements for accessory dwelling units.

Full Interior Finishes

The company installs interior finishes including countertops, cabinetry, tile, fixtures, and other elements needed to complete the living space. The goal is a finished unit that is comfortable and suitable for occupancy.

Energy-Efficient Building Practices

Cornerstone Builders Inc incorporates energy-efficient solutions and modern building materials into their ADU construction work. This approach is aimed at reducing ongoing utility costs for occupants and limiting the environmental footprint of the build.

For homeowners looking for a granny flat builder, backyard cottage builder, or a contractor experienced with casitas and JADUs, Cornerstone Builders Inc offers a structured process that covers design through completion. Their services are designed to take a project from planning to a finished, livable unit.

Services

Cornerstone Builders Inc performs the following services

Architecture & Design
Construction
Finishing & Fit-out
3D renderings & floor plans
HVAC installation

Cornerstone Builders Inc Reviews

Erin Sorenson

2026-01-06

"Cornerstone built our dream house and went way BEYOND our expectations. They were so communicative and open about all of our wants and needs and always kept a professional business relationship. Although, after working so closely with them they have become family. Every detail was built to perfection and if anything ever came up, it was handled without question. I had some specific and perhaps outlandish ideas and they listened, smiled and then executed exactly what I had envisioned. The subs they hired were also incredible. Their craftsmanship, communication and attention to detail were unmatched. They work with the best in the business. It was such a great experience that I wake up every day full of gratitude for them and for what they helped us build. I am so glad it's finished, but sometimes I wish we were still working on it because it was such a joy picking out all of the beautiful elements and watching them come to life in the space. Guests are blown away, and everyone loves being at our home. It is elegantly designed and can fit lots of friends and family, but is cozy and welcoming at the same time. It is exactly what we wanted to achieve and we couldn't be happier or more grateful for Allen and Bre!"

Betty Farris

2025-07-04

"July 2023: I hired Cornerstone to rebuild my side patio and add a swing. I was extremely pleased with the results! Allen and his team were very professional and courteous. I would definitely hire them again! July 2025: I needed a new roof and my first call was to Cornerstone. I knew they would treat me well and get the job done right. My job was completed in 2 days and I am very pleased with the outcome. It is nice to have a Contractor I can trust to not take advantage of me. They are always professional and kind. Thanks Cornerstone!"

Lisa

2025-07-03

"Cornerstone remodeled our house 3 years ago. They did an amazing job! I was thrilled with the results. Earlier this year our range hood started dripping water. I contacted Cornerstone to come investigate. Allen quickly figured out that there weren't enough roof vents for our size house. The ones we did have were blocked with debris. The roof plywood absorbed as much moisture as it could and the rest found a way down our hood. We had Cornerstone add the necessary vents and replace the roof since it was time. I will always turn to Cornerstone for any repairs or upgrades that my home needs or I want! It gives me such piece of mind to know our home is in good hands. I trust Allen wholeheartedly. He is definitely one of the good guys."

Brent Mesquit

2025-05-30

"We knew it was going to be a large projectfull kitchen renovation and four bathrooms, adding flooring to two levels and a smaller downstairs kitchenso we interviewed several contractors. We were so happy to work with Cornerstone and continue to daily enjoy the excellent workmanship in our home. Allen and team were not only professional, but easy to work with as they went above and beyond. He would clearly present us options as the work progressed and was always available to answer questions. He did a masterful, and timely, job managing all the people that are necessary for a large project. We never worried about our project and I cannot say enough good things about the quality of the work. Our home ended up as an award-winning renovation and we get compliments from our friends and family on how it all turned out. We are so glad we went with Cornerstone. -- Brent Mesquit"

Lisa Farris

2021-09-11

"Cornerstone brought back our faith in the Construction industry. They are professional, knowledgeable, and dedicated to making dreams come true. We hired Cornerstone to remodel our entire 1970s ranch style home. We are beyond thrilled with the results! There are a few reasons we chose Cornerstone. First, Allen was honest and upfront about how expensive remodeling a home can be. Having not remodeled in over a decade, we were ignorant to the cost and appreciated the dose of reality. Second, Allen came up with an amazing idea for our master bedroombathroom within the first few minutes of seeing the room. His design allowed for optimum use of the space and turned out to be the exact look and feel we never thought possible without an room extension. Finally, we liked that Cornerstone is a small locally owned company. We were able to get to know and trust the people that would be in our home. It is apparent that Allen chooses the subcontractors carefully. They were all efficient, friendly, and respectful. We chose to live in the house during remodeling. In hindsight, we underestimated the stress involved and overestimated our patience for the time it takes to remodel a home. Luckily Cornerstones Project Manager, Bre, was always available. She handled any concerns, questions, or anxieties that arose with understanding and compassion. This was a long, arduous process that resulted in our dream house. Allen has created a home for us that we never knew we could have. We are beyond satisfied!"

prev next

Specifics

Eco-Friendly Turnkey Solutions

Opening hours

Monday 9:00AM - 5:00PM

Tuesday 9:00AM - 5:00PM

Wednesday 9:00AM - 5:00PM

Thursday 9:00AM - 5:00PM

Friday 9:00AM - 5:00PM

Saturday -

Sunday -

Location

Get directions

Did we help?

Please let Cornerstone Builders Inc know that you found them on Top ADU Pros to allow us to continue helping others find the best adu contractors.

get in contact

About Cornerstone Builders Inc