The two companies will have a total of 115 employees. No layoffs are planned as part of the deal.
Final details, including the merged firm's name, are to be finalized in the coming months, the companies said in a release.
In the Triangle, the combined company will continue to operate out of Stewart's office in Raleigh and HadenStanziale's office in Durham. The Charlotte offices of the two companies will be consolidated into the Stewart office at 200 S. College St.
Stewart and HadenStanziale have worked together on a number of projects over the past 17 years.
“Stewart Engineering and HadenStanziale have services that are extremely complementary with each other, and this merger will allow us to create a new firm that brings together the best of both organizations,” said Robert Macia, president of Stewart Engineering, in a statement.
“HadenStanziale’s strong history of award-winning landscape architecture and design work will be a tremendous asset to our clients. We feel we can now offer the best in planning and design in conjunction with strong engineering expertise."