Who we are


Honor the past, challenge the norm, and inspire the future.

Our name

We are often asked how we came up with our company name, The Ranch Mine. Before we formed our company back in 2010, we spent 7 months traveling around Arizona, exploring the rich history of our state. During these trips, a common thread started to emerge: the pioneer spirit. Everywhere we went we heard stories and saw manifestations of the driven, impassioned people, such as ranchers and miners, who were willing to endure hardship in search of a better life. This spirit is still alive and well today and serves as inspiration to design spaces that afford us the opportunity to imagine what’s beyond what we see in the present so we can strive for new experiences.

Our story

In 2009, Cavin Costello received his Masters degree in Architecture and made the drive to Phoenix, Arizona sight unseen, inspired by the complexities and opportunities to be had in the rapidly urbanizing southwest. He had not yet been a full day in Phoenix when he met Claire, a Phoenix native looking to make the most of her recent move back home. The two quickly bonded over their ideals of the built environment, how to improve upon it and its ability to influence. Not settling for a hard hit economy to dictate their next move, the duo decided to act. So, they bought a fixer upper and experienced first hand the trials and tribulations of a major renovation.

The two continued paving their own path developing the First Phoenix Green Construction Code project, designing for visionary real estate developers, and creating inspired homes for unique homeowners. Cavin and Claire have continued to push the envelope in designing for the pioneer spirit which has won them the 2019 HGTV Designer of the Year for their ‘Red Rocks’ project, a 2015 National American Institute of Architects contest that named them the “Future of Architecture”, landed them features on the NBC Today Show and with HGTV, and had their work published in numerous books and publications on 6 continents around the world.

Our mission

Design homes that root you in your community, provoke curiosity and exploration, and embolden you to do more of what you love.

Our team

Behind every project we take on is a highly-skilled team. Following suit, our team is composed of adventurers who each possess the pioneer spirit and strive to break the boundaries of conventional thinking.

Cavin Costello

Principal Architect

Cavin Costello is the son of a civil engineer who endeavored to build his own house in rural Connecticut. It is safe to say that this exposure to building systems mixed with a “go get ’em” attitude laid the foundation for Cavin’s future. Cavin pursued his childhood passion at Northeastern University from which he earned a Bachelor of Science in Architecture and a Master of Architecture degree, graduating Summa Cum Laude. During his schooling he was able to study in and call Florence, Italy home, using that time to explore the country, building his appreciation for history and how culture and context affects the built environment. His enthusiasm for adventure led him to Phoenix, Arizona where he has become a prominent figure in the community. To date, Cavin has designed over 175 projects around the United States and the world, winning multiple national and local awards, including HGTV’s “Designer of the Year” in 2019 and “The Future of Architecture” award from the American Institute of Architects in 2015. Cavin is a licensed Architect in Arizona, Tennessee, Montana, Colorado and North Carolina.

Claire Costello

Chief Executive

Claire Costello is a native Phoenician who received unique exposure to rambling ranches, mid-century modern and desert architecture. Claire was young when she was asked to pick up a shovel and do some dirty work at her aunt and uncles in Tucson. This “dirty work” was digging dirt to build the first rammed earth house Claire had ever known of. Leaving the desert behind, Claire ventured to the University of Colorado at Boulder where she received concurrent Bachelor of Science degrees in English and Communication. Her time away from Arizona led Claire to travel the world, fueling a desire to make real change and igniting a belief in the power of action. Upon returning to her hometown, Claire sought to make a familiar place new, exciting and her own. Emboldened with an entrepreneurial spirit, Claire is committed to reclaiming her hometown of Phoenix one home at a time. Today, Claire embraces a hands-on approach to design and development and works toward shaping a more vibrant community.

Rachel Connor Karle

Project Architect
Rachel Connor Karle

Growing up in Arizona, Rachel developed a robust appreciation for the joys and challenges of desert-dwelling. After years of traveling to different states and countries, learning from various cultures and people, she returned to Phoenix in order to employ that knowledge while engaging with the built environment. This, in addition to her background in both architecture and engineering, has allowed Rachel to approach design with a unique perspective that she continues to develop and apply to every aspect of a project.

Rachel joined The Ranch Mine in 2018 shortly after receiving her Masters of Architecture from UCLA. She also earned her bachelor’s degree in Structural Engineering from Brown University. She is a registered architect in the state of Arizona.

Geoff Sosebee

Senior Designer
Geoff Sosebee

Geoff grew up in Georgia during a time when houses were being built by the hundreds. Walking through those neighborhoods during construction is when he fell in love with Architecture. It was also during this time that he was first introduced to the desert southwest during a backpacking trip to New Mexico.

After undergrad and living in Europe, Geoff moved to Oregon for graduate school for a change of pace and scenery. It's here that his passion for mountain biking, trail building, and architecture began to really formulate. He spent a number of years working on projects of all scales and typologies including; digital fabrication, creative office renovations, performing arts centers, multi-family residential, and various mass timber projects. During this time with Lever Architecture, he was able to focus on his original love of residential architecture, working on a number of residential projects over a few years.

In an attempt to escape the pacific northwest winter, he found himself in Phoenix for a sunny vacation and it's there that his childhood memories of the desert southwest resurfaced and he knew he needed to find his way back there professionally.

Geoff holds a BS in Architecture from Georgia Tech and a MArch from The University of Oregon.

Nicole Mehaffey

Project Architect
Nicole Mehaffey

Nicole was raised in Southern Louisiana where art classes, folders of unbuilt treehouse designs and a deep curiosity for the region's unique blend of culture, architecture, music, and cuisine were her gateways into the creative world. Hurricane Katrina expanded her understanding of the boundless powers of nature over the built environment, influencing her choice to pursue an architectural education.

After graduating with a combination BS and MArch from Tulane University, she sought out a new and entirely different locale by moving to Phoenix. She spent over 6 years working in commercial architecture on a varied collection of project types and scales, including multifamily residential, municipal, master planning, adaptive reuse, and behavioral health care.

Nicole enjoys reading, cooking, and exploring, and has gotten to know the desert intimately through camping, offroading, hiking, and paddleboarding. She joined The Ranch Mine in 2022 and is a registered architect in the state of Arizona.

Benjamin Johnson

Visualization Specialist
Benjamin Johnson

Benjamin was born and raised in the United Kingdom, where he earned a Bachelor of Architecture at the University of Lincoln. Ben went on to work with a variety of successful architects in the UK whilst continuing further studies in architecture. His love of travel ultimately led him to the United States and a move to Arizona in 2015.

Having gained a wide experience in high end residential and commercial projects, both in the US and Europe, his passion for exceptional design continued him on a path to The Ranch Mine in October 2018. Specializing in 3D visualization and representation he became an integral part of any project.

Katie O'Connell

Project Architect
Katie O'Connell

Growing up in Tennessee, Katie developed a love for varying landscapes from the plains along the Mississippi to the old forested mountains of the Smokies. This gradually evolved into a passion for experiencing different cultures of the world, understood through not only the landscape of the place, but also the food, architecture, and people. After working in London and New York, she decided to return to the mountains, this time in a valley surrounded by giant Doug Fir forests and old sleeping volcanoes - Portland, Oregon.

Katie has ten years of experience in creative office, hospitality, mass timber structures, and high end residential. Her passion lies in the latter, where architecture becomes most personal and tactile. Katie’s focus on exceptional design lends to architecture that is of a place while also deeply personal and reflective of the clients she works alongside.

Katie joined the Ranch Mine in 2023. She holds a Bachelor of Architecture from the University of Tennessee and is a licensed architect in the state of New York.

Stefan Kaiser

Project Architect
Stefan Kaiser

Stefan grew up in Reno, NV, surrounded by the diverse landscapes of the high desert. Spending summers and winters engaging in outdoor activities at Lake Tahoe, he developed a deep appreciation for the environment. During a high school internship program he discovered his passion for designing living spaces that coexist with nature, drawn by the intersection of rational and artistic potential and the opportunity to influence people's lives.

In college he expanded his knowledge of architectural history in Florence and honed his skills by apprenticing for a professor of architecture in Hamburg. Graduating from the Syracuse School of Architecture, Stefan earned multiple awards for his thesis project on diplomatic structures.

With a decade of experience under his belt, Stefan has worked on large and small projects at every phase of construction. Single family homes, apartment buildings, mixed-use towers, restaurants, and commercial office spaces to name a few. He enjoys navigating the complex challenges of designing and constructing architecture as a trusted advisor of his clients and an enthusiastic partner to the builders he's collaborated with.

Stefan joined the Ranch Mine in 2023. He is licensed in Arizona and Washington, a LEED Green Associate, and certified by the National Council of Architectural Registration Boards. Currently residing in Tucson, AZ.

National and International Awards & Honors


Best Single Family Detached Home 3000 to 3,499 SF, Gold Nugget Awards – 2023
Best Project 2022, Archilovers – 2022
Top Home Tastemaker on Contemporary Design, Artful Living Magazine – 2022
Top 10 Sustainable Homes of 2020 – #3,
Dwell Magazine – 2020
Best Project 2020, Archilovers – 2020
Designer of the Year – Before + After, Editors’ Choice Winner, HGTV – 2019
Designer of the Year – Before + After, People’s Choice Winner, HGTV – 2019
10 Talented Architects Leading the Way with Site-specific Designs that Engage with Nature, Luxe Magazine – 2018
Top 10 US Houses of 2017, Dezeen – 2017
Top 20 Homes of 2017 – #12, Dwell Magazine – 2017
2017 Building of the Year Finalist (United States), American-Architects – 2017
The Future of Architecture: Innovation, Winner, American Institute of Architects (AIA) and Houzz – 2015
Designer of the Week, HGTV – 2015
Green Remodel of the Year: National Award-Winner, National Association of Home Builders – 2012
Best Homes Across the Country under $250,000, NBC Today Show – 2012

Local Awards & Honors


Home of the Year – Home Builders Association of Central Arizona – 2022
Best Architectural Design: Homes From $800,000 - $1,000,000 – Home Builders Association of Central Arizona – 2022
Design Icon – Architect,
Sources for Design Magazine – 2021
Gold List, Luxe Magazine – 2020, 2021, 2023, 2024
40 under 40 Inaugural Class, Phoenix Magazine – 2018
Best of Houzz: Design, Houzz – 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023
Big Brain Award Finalist: Design, Phoenix New Times – 2015
35 top Entrepreneurs under 35 , The Arizona Republic – 2013
Best Emerging Creative Duo, Phoenix New Times – 2013
Top 100 Creatives, Phoenix New Times – 2012

Public Speaking Engagements


Taliesin Next: Design in the Desert – 2019
AIA Western Mountain Region Conference – 2018
Modern Phoenix Week – 2018
PHX Architecture Forum – 2017
Arizona Historic Preservation Conference – 2017
American Institute of Architects Arizona Associate Conference – 2017
Arizona Historic Preservation Conference – 2016
Design Within Reach, Design Days – 2016
Arizona Historic Preservation Conference
– 2015
Phoenix Urban Design Week – 2015
Modern Phoenix Week – 2014
AIGA PechaKucha: Design for Good – 2014
Arizona Historic Preservation Conference – 2014
Reinvent Phoenix – 2014
Modern Phoenix Week – 2013
Arizona Historic Preservation Conference – 2013
TEDx Phoenix – 2013
Arizona State University School of Urban Planning – 2012
Retrofitting Sprawl Symposium – 2012
Northeastern University School of Architecture – 2012

Where we've worked so far:


While our firm is based in Arizona, we work for clients with the pioneer spirit around the United States and the world. Below is the list of the places where we have worked so far.

North Carolina


Our work


looking through a pivot door to a boat house on a lake
Reach out