Construction products supplier SIG traded 'in line' during the first four months of the year, with sales growing by 8% on the same period in 2010.However, the firm notes that this was against a weak, weather-affected corresponding period in 2010, and growth has moderated from March as a result of tougher comparators.These are expected to continue into the second half of the year, along with the potential impact of limited public spending."Given the uneven pattern of 2010's first half comparators, it will be mid-year before the group has a better view on the expected full year performance," the statement said.SIG said that its divisions in the UK and Ireland have shown growth (with the exception of Interiors Manufacturing and Energy Management), while progress has been made in France, Germany and Poland & Central Europe. However, the group highlights difficulties in Benelux.Gross margins across all regions are flat on last year.---BC