Floods on the east coast and soaring energy and fuel costs have triggered another hefty profit downgrade for concrete and asphalt group Boral, which is 70 per cent owned by billionaire Kerry Stokes and his family.

Chief executive Zlatko Todorcevski said on Wednesday full-year profits would be dented by $45 million, as disruptions from flooding and persistent heavy rainfall brought a $30 million hit, with rising inflation as coal, electricity and fuel prices jumped, making up the other $15 million.