2013 Grand National to modifications made for the previous year's race, Aintree announced that a number of further changes had been made for the 2013 National. Twelve of the 16 fences on the course were rebuilt with the timber frames within them replaced by a softer material known as "plastic birch". The fences are still covered with at least 14 inches of spruce and will remain the same height. The starting line was also moved 90 yards closer to the first fence, further away from the spectators' stands and thereby reducing slightly the overall distance. Aintree and the Professional Jockeys' Association jointly issued
Grand National them as formidable obstacles. After the 1989 Grand National, in which two horses died in incidents at Becher's Brook, Aintree began the most significant of its modifications to the course. The brook on the landing side of Becher's was filled in and, after the 2011 race which also saw an equine fatality at the obstacle, the incline on the landing side was levelled out and the drop on was reduced by between 4 and 5 inches (10–13 cm) to slow the runners. Other fences have also been reduced in height over the years, and the entry requirements for the race