The first phase of the Rehabilitation Project of the Lordelo Neighbourhood consisted of the preparation of a Diagnostic Study whose main objectives were to analyse the pathologies affecting the façades, the roofs and the common interior areas of the buildings and to present a methodology for the corresponding rehabilitation works; to assess the existing electrical installations in the stairwells and to propose solutions for the architectural rehabilitation of the outer shell. By choice of the project owner, the exterior arrangements were immediately excluded from the scope of the rehabilitation project. The buildings of the Lordelo Neighbourhood, which were built in 1978, presented several pathologies and their image was deeply uncharacterised by the most varied alterations and partial interventions which, besides creating great heterogeneity in the appearance of the external surroundings of the buildings, in some situations conditioned their behaviour. The main objective of the rehabilitation of the buildings was to solve the existing problems, making the sometimes conflicting demands compatible, such as hygrothermal comfort, energy conservation, durability and the functionality of the solutions. The rehabilitation of the Lordelo Neighbourhood allowed the buildings’ constructive coherence to be recovered and the construction to be adapted to the most current demands and standards. Whenever possible, construction materials were used in their natural expression, as was the case with the original solutions.