On these roofs which are impermeable, it is doubly important to check the waterproofing due to the movements of the building itself or eventually due to the effects of wind, snow, etc...
 
PROCEDURE: following the New Technical Building Code all roofs have the same degree of waterproofing. A waterproof membrane can be laid on an appropriate support with up to 15% incline, mechanical anchorage is required for inclines over 15%. The following will be taken into account:

· 26% incline for CURVED tiles
· 30% incline for mixed tile and flat monochannel
· 40% incline for Marseille or Alicantina flat tile
· 50% incline for single lap interlocking tile
· 60% incline for slate
· 10% incline for zinc