The system of the invention, which involves a plurality of modules in which a framework based on aluminium profile sections is defined, makes provision such that, in the front zone of said profile sections, via the corresponding heel plates, three chambers are defined such that, under normal conditions, only the front (4) and rear (6) chambers are used to receive the corresponding vertical gaskets (10-10'), in the case of lateral connections, or of the appendices (8-8' - 9-9') of a sill gasket (7), in the case of horizontal connections, such that when it is necessary to install a bracket (1 1), and therefore necessary to drill the vertical gaskets (10-10'), the bracket incorporates a shield (12), transversely thereto, which is designed to be accommodated with interposition of the corresponding leaktight gasket (13) on the intermediate chamber defined between profile sections, ensuring that such moisture as might be able to access said intermediate chamber is drawn downwards towards the sill gasket (7) for expulsion to the outside of the wall.