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Jeff and Mary wisconsin construction company


JG Development was founded in 1990 by Jeff Grundahl, and his wife Mary Grundahl joined as co-owner in 2005. The Grundahls began the process of transitioning the company to employee ownership in 2018.

Jeff and Mary are long-time residents of Mount Horeb, Wisconsin. Together, their goal is continued growth of JG Development and its four divisions, and the industries and communities they impact.

In her role as chief operating officer, Mary leads the management team and business plan and guides a mission driven culture, drawing on a professional background in sales, marketing and strategic growth planning. She is also a philanthropist and lends leadership to initiatives and organizations focused on economic development, trade education and health. Mary is a Past President of the Mount Horeb Area Chamber of Commerce and a recipient of its George Sievers Award for community service.

Jeff focuses on the future of the company in his role as founder and chief executive officer, exploring opportunities for innovation and growth. He has more than 30 years of experience in residential and commercial new construction and remodeling and has served the National Association of the Remodeling Industry (NARI) of Madison, Construction Resource Network and various economic development efforts. Jeff is a NARI of Madison Lifetime Achievement Award recipient. He is also the co-founder and co-owner of development company TRI Holdings.

Jeff and Mary are proud to lead a team of nearly 50 professionals who operate from the company’s office in Madison, Wisconsin.

Employee Ownership

JG Development Team

JG Development is minority employee owned and plans to transition to 100 percent employee ownership in the near future.

What does this mean for employees?

The JG Development Employee Stock Ownership Program (ESOP) provides employees financial security in retirement. Shared ownership promotes a positive, team-oriented work environment. All of these benefits are provided without any financial investment on the part of employees. New employees are eligible for the program after just one year of service if they meet basic requirements.

Explore our open positions and consider joining our team of employee owners!

Why did JG transition to employee ownership?

Majority Owners Jeff and Mary Grundahl initiated the ESOP in 2018 to reward employees who had helped grow the company to what it had become. Employee ownership was a good fit for the existing family-owned cultures of JG Development and its acquisitions Roberts Construction Associates and National Construction. The ESOP was also the beginning of a long-term succession plan, which Jeff and Mary intend to protect the interests of dedicated employees.

What does this mean for clients and partners?

JG Development employees have a vested interest in the success of JG Development. They are proud to be a part of the company and committed to delivering both a high-quality experience and high-quality construction.

For more information about employee ownership, visit The ESOP Association or the National Center for Employee Ownership.


JG Development is proud to share with its clients many local, regional and national awards, a true testament to our commitment to clients and the quality of work we strive to achieve. We invite you to visit our division websites for a complete listing of awards:


At JG Development, we know that our team is the key to our success. We are committed to creating a workplace and jobsites where integrity and accountability are encouraged and recognized. We offer competitive pay and benefits, and high-quality training and resources.

We are always interested in connecting with qualified and motivated construction professionals. Please contact us if you are interested in a career with JG Development.