Managing director Michael Knipper said the group now expected sales growth of up to 10 percent, versus a previous estimate of up to 7 percent, in 2011 as uncertainty on financial markets drove interest in real estate. 

But looking forward, Knipper said construction was facing harder times in 2012 as the debt crisis weighs on investment plans and public spending on construction projects fell. 

"It will be more difficult — the only area that will be positive for sure is housing construction," he said. 

Should the debt crisis stabilize, construction should do well, he said, but there remains a risk that banks reduce credit due to tougher capital rules. 

"Then there is the danger that the real economy is hit and some investments in corporate real estate construction will be more difficult or not possible," he said. 

Economic indicators show a slowdown is in the cards for the German economy, but the particularly resilient construction sector has helped drive surprise increases in business confidence. 

Germany recovered better than most from effects of the 2008 financial crisis, but concerns over its ability to weather the debt crisis were underlined earlier this month when a survey showed manufacturing contracted for a third straight month in December and exports posted their biggest fall in October in half a year.