By Reuters Staff (Adds details on outlook, background) Jan 11 (Reuters) - SIG Plc said on Monday it expects losses for 2020 to be at the “better end” of its expectations and that it could return to profitability in the second half of 2021, as the building materials supplier recovers from a COVID-19 pandemic-led slump. SIG, which supplies roofing and insulation materials in Britain, France, Germany and Ireland, among others, said its UK and French businesses witnessed solid demand for renovation, maintenance and improvement during the pandemic. Britain’s construction sector extended its robust recovery from a COVID-19-related lockdown early in December, a survey showed last week, with housing being the biggest driver of construction growth.