David Clark and Paul Mansell, who resigned from MDA in February 2003, started their new firm, Matrix, last week.
Matrix has a staff of five, although its business plan envisages a workforce of 50-60 within four years. The firm has secured civil engineering and residential work, and is in talks with developers for further projects.
The two stressed that the parting was amicable. Clark, who had been at MDA for 19 years, said: "There is no rift between ourselves and them. We have a good dialogue – we are exchanging business details and contacts. If there was a rift we certainly wouldn't be doing that."
Clark said the two had been thinking about setting up a new firm for "six months to a year".
I am the old boy who will try to help them out
Clark said: "We needed a new opportunity. It's very exciting."
The two said the tightening in the market would suit their venture. A statement said: "As the market tightens, cost certainty and best value are paramount to clients' needs."
Matrix is owned by Haley Somerset Holdings, the parent of QS firm Haley Somerset. This was founded by David Somerset in 1989; Somerset served a brief stint as the managing director of MDA in 2002 after working for it in the 1980s.
Somerset said the two founding directors of Matrix would be given share options as the firm grew. He added that the three had discussed the venture after he left MDA last year.
Somerset left as part of a restructuring of MDA, a process led by chairman Charles Johnston and director Grant Tromans.