Turnover also dipped below the £1bn mark, sliding to £946m in 2011.
Bam Nuttall faired better with profits down just 9% at £14.3m on turnover up 17% to a record £809m.
Orders at the civil engineering division were boosted by major wins on the Crossrail project.
Bam UK contracting results
Bam Construct: profit £11.5m, down 33%; turnover £946m, down 9%; operating margin 1.2% (2010: 1.6%)
Bam Nuttall: profit £14.3m, down 9%; turnover £809m, up 17%; operation margin 1.8% (2.2%)
Martin Rogers, member of the Executive Board of Royal BAM Group, said: “The steady performance is the result of a heightened focus on prudently managing the difficulties inherent in the UK market.
“The companies have resisted the temptation to bid at unsustainable prices, have concentrated on maintaining standards and additional management and supervision of the supply chain.”
Graham Cash, chief executive of BAM Construct UK, said: “The company has demonstrated great flexibility and versatility in 2011, completing projects that ranged in value from £1m to £132m.
“In 2011, we won business from important new clients such as Network Rail and positioned ourselves for new areas of work such as qualifying to bid for the MoD NGEC framework.”
