Andrew Wyllie, the chief executive of Costain who was appointed last September, has completed a strategic review of the business and plans to slash the sectors in which the company operates from 15 to 10.
Areas that the company is looking to exit include high-residential schemes and one-off property developments.
Speaking after his first annual results presentation at Costain on Wednesday, Wyllie said: "The plan we have set out is absolutely predicated on organic growth."
Wyllie has outlined his goals for the company in a document released to staff called Being Number One.
The document says the company's aim for the next three years is achieving a double-digit increase in profit and turnover by being number one in every sector in which it operates.
Wyllie said: "We are already number one in asset management in the water sector and I would defy anyone that wouldn't say the same for roads."
Wyllie said Costain would also focus on the health, education, nuclear, rail, marine, retail, airport and oil and gas sectors.
In the year to 31 September 2005, pre-tax profit at Costain increased 6% to £21m and turnover rose to £773m, up 11%.
Speaking about Iran, where Costain's oil and gas business is part of a consortium appointed last year to build the £950m Bid Boland II gas treatment plant, Wyllie said: "Clearly since then the world has changed and we are monitoring the situation."
He refused to comment on whether it had sought legal advice in the event of an imposition of sanctions by the UN.