The £790m facility, together with private placement funding and convertible bonds, now gives Carillion access to a £1.4bn war chest.
Carillion group finance director, Richard Adam, said: “Extending our main revolving debt facility by nearly three years at improved pricing, clearly indicates the strength of Carillion’s credit standing within the debt capital markets and their support for our strategy for growth.”
The Group had annual revenue in 2014 of some £4.1bn.