The deal with Royal Mail will also see Balfour take full control of mobile facilities management specialist Romec Services Limited, which employs around 200 staff around the country.
Under the two-part deal Romec, which was formed in 1992 as a Balfour Beatty/Royal Mail jv, will carry out technical and building services for Royal Mail, Post Office and Parcelforce Worldwide buildings.
This will be worth £150m a year but also has scope to be doubled in size over the 10-year framework.
Balfour Beatty has also separately bought Royal Mail’s stake in Romec Services Limited, a standalone mobile FM contrcator working for client like Sainsbury’s, Asda, BBC, British Museum and Camelot.
The new business will come under control of Balfour Beatty Workplace, spring-boarding the firm into the fast growing mobile FM sector.
Balfour Beatty said that RSL’s £36m revenue and £13m gross assets would support its growth plans in the facilities management sector.
Balfour Beatty chief executive Ian Tyler, said: “The joint venture we have developed with Royal Mail Group is now entering a new and exciting phase.
“We are delighted to develop the new Romec organisation from a tactical supplier to one of Royal Mail’s key strategic partners, supporting its transformation programme.
“We are also excited about the opportunity to develop RSL. The combination of RSL’s engineering skills and the breadth and resources of our support services business can enhance our service delivery model and capitalise on the potential growth in facilities management.”