Geoff Cooper, chief executive, said: “While weather patterns normally average themselves out over any trading period, it has been difficult to ignore the impact on the results of the first half trading of the wettest three months since records began.

“This has inhibited construction activity and particularly constrained turnover in our heavy-side related businesses in a market already struggling to recover to more normal levels.

“We estimate normal weather conditions would have boosted profits by around £10m.”

He added: “Despite this, we have, in balancing sales volumes and gross margin, traded sensibly throughout the period across all four divisions, continuing to take like-for-like market share, increasing the group’s gross margin and remaining cautious on costs and capital expenditures.”

In the first six months of the year group revenue edged up 2.7% to £2.41bn with adjusted operating profit before property profits up 10% at £151m.

Cooper said that much of the gain had come from increased marketshare.

He added: “External estimates suggest that overall market volumes have contracted by approximately 5% year-on-year and we fully expect that this rate of contraction will continue for the rest of this year.”