Shares in plumbing supplies group Wolseley fell almost three per cent after a one-off charge and struggling European markets offset strong demand for its services in the United States.

The company, which operates the Plumb Center and Ferguson chains in the US and Britain, reported a £245 million impairment charge on Tuesday relating to its 2006 purchase of DT Group in the Nordic region.

The charge pushed Wolseley to a net loss of £58 million in the six months to January 31.

"Shares in Wolseley have leaked to the foot of the UK's flagship index this morning ... dented by impairments to its Nordic business which compound the diverging fortunes of a recovering US and struggling European markets," said Mike van Dulken, head of research at Accendo Markets.

Wolseley, which operates in the United States, Canada, UK, Nordics, Central Europe and France, said it expected underlying group trading profit for its financial year to be in line with expectations after strong demand in the United States helped earnings rise 12 per cent in its first half.

The company paid an interim dividend of 30.25 pence per share, an increase of 10 per cent.

Underlying trading profit rose to £390 million for the period, compared to £351 million a year earlier.

The company also said it expected a like-for-like revenue growth rate in the second half of the year of around six per cent.

Wolseley said it had seen very strong revenue growth and market share gains in the US, which accounts for 76 per cent of its trading profit. Revenue grew by nearly 12 per cent on a like-for-like basis in the first half of the year.

Chief executive Ian Meakins, in the role since 2009, said he expected improvements in its markets like Canada, Britain, Sweden and Denmark over the coming months.

"We do expect to see improvements in the second half of this year versus last year ... overall we are pleased to see a better topline performance across the whole of the group," he said.

"We are working hard to make sure we get the flow through in Europe in the second half of the year and we are confident we (will) continue to deliver good attractive growth for the short and the long term," he added.