By Sylvia Westall

FRANKFURT (Reuters) - Bilfinger Berger (GBFG.DE: Quote, Profile, Research), Germany's second-largest builder, reported first-quarter profits that beat expectations, helped by earnings from maintaining buildings and factories.

Earnings before interest, tax and amortisation (EBITA) more than doubled to 40 million euros ($61.83 million) in the first three months of the year, 18 percent more than expected.

Seven analysts in a Reuters poll had on average estimated EBITA of 34 million euros.

The company's stock was up 5.9 percent at 57.49 euros by 0844 GMT, outpacing the MDAX index of medium-sized German companies which rose 1.6 percent.

"Bilfinger manages to push through good margins in its services business," said Bankhaus Lampe analyst Marc Gabriel. "The company is on the right course."

Chief Executive Herbert Bodner is expanding Bilfinger's services business -- which maintains power stations, hospitals and plants -- to make it the biggest earnings contributor and leave the company less dependent on declining construction demand in Germany.

Earlier this year he agreed to buy the repair and maintenance activities of Norsk Hydro (NHY.OL: Quote, Profile, Research) for about 100 million euros and Australian electrical engineering company iPower Solutions.

All major earnings figures beat market expectations. Pretax profit rose to 38 million euros from 13 million euros a year earlier, compared with analyst estimates of 31 million euros.