The support must be executed with 1% to 2% slope. The waterproofing must prevent the passage of water into the interior, ensuring that the singular points (connection to parapets, chimneys, etc.) are planned with special attention. When asphaltic membranes are used, a geotextile shall be applied between them and the insulation layer. The insulation shall be dimensioned in order to reduce heat transfer to the interior.
The geotextile ensures the filtering of rainwater so that the wastes are not drawn into the gutters and downpipe.
The paving prevents the wind from pulling off the insulation, and protects it from sunlight.