Fletcher Building, the troubled Auckland-based building materials giant, says it expects sales volumes to slide by up to 15 per cent in Australia and New Zealand as it raises $NZ700 million ($641 million) to shore up its finances and cut debts.

Fletcher, which has lost the confidence of investors after a series of profit downgrades and operational mis-steps, generates half of revenues from residential construction. It said a 30 to 40 per cent downturn over the past two years had hit hard.