2. Surface containment

2.1 General principle

The surface covering is generally made up of a multi-layer device consisting of superimposed elements which are, from top to bottom (figure 5 ):

• a surface layer ;

• a protective layer ;

• a rainwater drainage layer;

• a sealing layer ;

• a foundation layer for the upper elements of the roof, to ensure gas drainage if necessary.

• The surface layer

  Its role is to separate the underlying layers of cover from the atmosphere....