We tie off to secure existing structures on the roof. If anchors need to be added, we put eye-bolts into the parapet wall only. If it is a metal screw down roof, then we simply use the existing hole where the metal sheets are secured to the steel beam. We back that screw out, add the anchor strapping, reapply the screw and calk thoroughly. The balloons cannot be weighted down. All roofs are different. There are 2 types of roofs that may prevent us from installing the pumpkin if there is nothing to tie to. Standing Seem roofs and White Membrane Roofs. We CAN install on membrane roofs but if we have to put anchors in the parapet and we require written landlord approval. Pumpkins are 25 ft tall and 17 ft at its widest diameter. The inflatable weighs approximately 75 lbs.