Birmingham quantity surveyors and project managers the Davidson Partnership has been bought for an undisclosed sum.
Davidson, which specialises in the pharmaceutical sector, was purchased by Oxford-based building consultants Ridge.
Ridge has also agreed to buy Cook Denning, the health and safety subsidiary of Davidson.
Both companies, which are based in Moseley, employ 25 people and have a combined turnover of £1.6 million.
Ridge will retain all of the current team, including Peter Cook, Ross Denning and Greg Fanning who are partners and directors in the two businesses.
Mr Cook will be retained as a consultant, while Mr Denning and Mr Fanning will continue in Birmingham as partners of Ridge.
Expanding into the West Midlands would allow Ridge to develop and build its business in the region and grow the newlyacquired company into another successful multi-disciplined team, the company said.
Phil Jones, senior partner of Ridge, went on: "This acquisition is a significant step forward in the ongoing growth of Ridge.
"The Davidson Partnership is a successful, dynamic firm; its acquisition will help to extend Ridge's presence in the West Midlands. It is a good fit both geographically and in terms of complementing our skill set and disciplines.
"We shall continue the good work for all our existing clients, whilst growing the business."