Cyril Sweett has begun redundancy talks with an unspecified number of its 900 staff.
After announcing strong results for the six months to 30 September 2008, the company said it needed to reshape the business to match its order book.
Dean Webster, the chief executive, said the final number of redundancies depended on how many staff were prepared to move overseas or into its public sector divisions.
He said: “It would be unrealistic to say some redundancies won’t be necessary but we’ve told people they need to be as flexible as possible.”
Webster said the company has moved about 20 people from private to public sector work in the past year, while its Middle East division has grown from 20 to 70 people.
Pre-tax profit rose 32% from £2.5m to £3.3m over the period on the back of a 40% jump in turnover from £29.3m to £41m.
The contribution to turnover of public sector work has grown from 42% to 58% in the since the first half of 2007.
The company ended its half-year with net debt of £200,000 and £7m in unused credit facilities. Webster did not rule out further acquisitions next year.