DOI: 10.7764/RDLC.16.3.420AbstractThe injection of expansive polyurethane resin into the soil is a technology that is beginning to be used for underpinning shallow foundations. It is noteworthy that this technology has been used on buildings of great historical value which are part of the country’s architectural heritage. This article describes the work done on the Cardinal Diego de Espinosa Palace which consisted of injecting expanding polyurethane resin into the soil at different depths (Uretek Deep Injections) in order to mitigate the differential settlements detected in the structure. This injection technology has proven to be more effective than the more convention methods used in the past which consisted of raising the foundation by building concrete shafts, which did not manage to mitigate the causes of the pathologies observed in the palace.