Building products firm SIG said there has been a "clear slowing" in the rate of decline in construction activity, led by residential new build and repairs, maintenance and improvement (RMI).The group said the recent trading trends continue to point to a levelling out in monthly sales sometime in late summer 2010."As previously anticipated, it now appears by year end that some of the sales lost in Q1 due to the extreme weather will be recovered, though not all, particularly in Europe where the duration of the disruption was longer than in the UK and Ireland," said the group.Cold weather caused building site activity being restricted and deliveries unable to be made in the early weeks of the year, with a corresponding adverse impact on first quarter sales. Sales in the period 1 January to 12 May 2010 were lower by around 6% in constant currency terms, compared to the same period in 2009. Excluding the exceptional impact of the extreme weather, underlying trading in Q1 was in line with management's expectations.