The Reading-based group, which earns around half of its annual £16 billion sales in the US, warned conditions were likely to deteriorate further this year.
Total pre-tax profits for the six months to 31 January 2008 fell 73 per cent to £79 million from £285 million.
Wolseley, which operates the brands Plumb Center and Build Center, said: “These results reflect the deteriorating US housing market and reducing consumer confidence arising from global credit restrictions.”
The economic conditions were also seeing weaker sales growth in the UK, the firm said, with revenues for its UK and Irish businesses up by 3.1 per cent in the period but trading profits down by 8 per cent.
Wolseley shares were nearly 4 per cent down today.