Expansive soils are responsible for tens of billion euros of annual worldwide damage cost. Soil expansion due to wetting and contraction upon drying cause various types and degrees of damage to buildings founded on expansive soils. Expansive soils can be found in many regions of the island of Cyprus but, most importantly, in major parts of the urban centers. Designing buildings founded on expansive soils still relies largely on empiricism, with the analytical basis on the actual physics and mechanics governing such soils. As a consequence uncertainties are inherently very large and design failures are quite common in many places in the world, including Cyprus. The goal of the proposed study is the development of optimal and sustainable foundation design and construction methods for buildings on expansive soils. The project involves field instrumentation, laboratory experimental work and numerical simulations. Existing and under construction buildings founded on the highly expansive soil call Nicosia marl will be fitted with sensors monitoring their response to seasonal moisture induced soil volume changes. In addition, stations of in-situ measurements of soil moisture, porewater suction and soil expansion will be installed at the sites of the instrumented structures. The project also includes a comprehensive experimental program of lab tests for the determination physical and mechanical properties of the Nicosia marl. Based on the field and experimental data, numerical models will be set up for the thorough investigation of the expansive soil – foundation interaction. Series of parametric numerical simulations will be performed in order to reveal which among the existing foundation solutions are more suitable for the geologic and climatic conditions of Cyprus and which are ineffective. Based on the results of the numerical simulations, simple foundation analysis methods suitable for direct implementation in common engineering practice will be developed.