Here is a simple rooftop playground installation we completed in NYC using our 2.5" thick "Play-Land" series in Green to give it the atmosphere of grass.
The customer had a vulcanized tile that was on the rooftop which was very slippery when wet, forcing the children of this Montessori school to remain inside (even after it rained) until the entire rooftop playground surfacing was completely dry.
After years of frustration, the school felt is was necessary to switch to a product that was much more water permeable, offered better drainage underneath to the drainage outlet in order to allow the children to get outside faster....and slip resistant (wet or dry). The end result.......... less injuries.
Keep in mind, the product selected (ours) had to be fire and wind resistant since it is indeed a rooftop; And ASTM complaint for children safety as it is indeed a playground area.