Chief executive Ian Tyler said: 'Balfour Beatty is, through Stent, already a leader in the piling sector and the acquisition of Pennine gives us a strong, complementary presence in ground engineering. We can now offer the full range of foundation solutions in the UK.'
Pennine is based in Bacup and has 130 staff. It turned over £16 million in the year to March, making operating profits of £1.5 million.
Balfour Beatty has also bought specialist German signalling contractor SBB for £9.7 million.
It will become a part of Balfour Beatty Rail Power Systems, Balfour Beatty's Munich-based subsidiary which specialises in rail electrification and power systems for international rail markets.
In 2004, SSB turned over approximately £6.9 million. The company has 85 employees and is based in Stassfurt, near Leipzig.
Mr Tyler added: 'The acquisition of SBB will offer us an important opportunity to broaden our signalling capability and to develop further our excellent existing relationship with Deutsche Bahn in Germany.'