New York-based STO Building Group has added West Coast builder Abbott Construction to its network of companies.
The privately held STO (formerly Structure Tone) said the merger will allow both better serve clients with multiple locations and enhanced services.
“The Pacific Northwest has been a key strategic market for the STO Building Group, and Abbott is a terrific addition to our family of companies,” said Robert Mullen, STO Building Group CEO.

“By joining forces, both firms can leverage each other’s geographic reach and take advantage of each other’s strengths, relationships, geographies, and resources to better serve our clients across the globe.”
STO restructured as the STO Building Group in 2018 to provide a platform for growth that allows each of its member companies to maintain their cultural identity while leveraging the strengths of a multicompany organization. In the last four years, Canadian firm Govan Brown and US firms Ajax Building Company, BCCI Construction, and Layton Construction have merged with STO Building Group.
Abbott, which has current revenue of about $250 million and 265 employees, will keep its identity, and its current leaders will retain an ownership position in the organization and maintain their roles as the senior leadership team of the business.
“From our existing relationship working with Abbott on two significant joint venture projects, we are confident that this merger is a great fit for both companies,” said David Layton, president and CEO of Layton Construction, who Abbott will report through. “And with Layton’s proximity to the Pacific Northwest and existing presence in Southern California, we’re looking forward to helping Abbott grow in those core markets.”
Founded in 1983, Abbott works in a variety of sectors such as healthcare, hospitality, education, non-profit, retail, and tenant interiors. Some of their most notable recent projects include the FAA Northwest Mountain Regional Headquarters in Des Moines, WA; Big Fish Games Seattle headquarters, the UCLA Margo Leavin Graduate Art Studios in Culver City, CA.
“The opportunity to merge with such an incredible firm as Abbott is exactly why we shifted our structure to STO Building Group,” said James Donaghy, STO Building Group executive chairman. “We value the reputation and heritage of the firms who merge with our organization, and each has kept its identity as a way to honor that legacy. As we continue to grow, we want to respect that history, but also reflect the collective expertise our companies offer and allow our employees to benefit from the larger organization’s resources.”
STO now has over 3,300 employees located in offices throughout the US, Canada, UK, and Ireland and nearly $8 billion in annual revenue. Services cover everything from site selection analysis, design constructability review and aesthetic enhancements to interior fit-outs, new building construction and building infrastructure upgrades and modernization.