The application of loose laid membranes require the polymer bitumen membrane to only be soldered on its lengthways flaps, side end flaps and on the perimeter parts of the area to be covered. This fact allows the waterproofing system to be independent from the underlying support. Whilst carrying out posa in indipendenza it is necessary to provide a heavy protection system, (gravel or paving) to avoid the possibility that the covering may be lifted up by the wind.