Pre-tax profits were up to £5.5m from £1.8m last time on turnover of £45.6m from £41.1m as underlying profit margins increased to 13.6% from 6.1%.
The company said: “Against a background of the continuing presence of Covid-19 and uncertainty surrounding the likelihood of a Trade Agreement being secured with the UK’s exit from the EU, Alumasc’s performance in H1 was outstanding.
“The 11% uplift in our revenues to £45.6 million reflects an increase in our market share won particularly in our Roofing business and Water Management Division.
“Following a refocus of the customer profile our Housebuilding Products Division’s revenue grew slightly, bolstered by the success of several new products across the last twelve months.”
Chief executive Paul Hooper said: “Reflecting the Board’s confidence in the year ahead, the underlying strength of the business and the strategic growth opportunities available to us, we have today proposed an interim dividend of 3.25 pence per share.
“Our long-term strategy remains to continue to deliver profitable growth through our strategic positions in sustainable building products, while growing our export market.
“In spite of some potential industry headwinds, we will focus on delivering this to generate sustainable returns for all our stakeholders.”