Earth as a building material is a very sustainable construction option. The vulnerability of earthen buildings to water action by rain, floods or capillary absorption is the main concern, especially in countries with a high rainfall. The historical earthen buildings that have survived these actions until today demonstrate that it is possible to build durable earthen constructions. A successfully used technique in ancient buildings is the incorporation of natural products with water resistant properties, such as oils, fats and other materials generally referred to as biopolymers. Another common practice has been the use of lime (slaked or quicklime) for stabilizing soils. The main aim of this research is to improve the resistance of compressed soil against rainwater action. For this purpose, ancient and contemporary knowledge was analysed. Different mixtures of stabilized soil were studied in order to test the effects of quicklime, oils and a mineral additive. The main results obtained in this research showed that quicklime leads to increased performance in compressive strength and significantly reduced erosion in the accelerated erosion test of rain simulation. This study provides a contribution to the scientific knowledge required to achieve increased durability for new earth buildings, as well as for conservation of existing earthen construction heritage, preserving the sustainability of the construction.