1. Introduction 1.1 Motivation 1.2 Objectives 2. State-of-the-Art 2.1 Motivation 2.2 Salts in Building Constructions 2.2.1 Salt sources 2.2.2 Physical and chemical effects and salt crystallization 2.2.3 Salt damage treatments 2.2.3.1 Passive techniques 2.2.4.3 Active techniques