All our lofts are calculated to loads that are far in excess of anything that could practically be put on them. We work on the basis of 150kg per square metre, as per BS EN 1991 which is the calculation used for first floors in domestic dwellings. According to the National Centre for Health Statistics a 7 year old had a maximum body mass index of 19kg per sq. metre so on this measure you could fit 7.5 of the largest children on each square metre of the platform (although this would not be physically possible unless you stacked them on top of each other 3 deep!).