An extensive airtightness measurement has been carried out on 159 social housing units built in southern Spain. The sample includes homes from multifamily buildings built since the origin of social housing models in 1950, through to the most recent examples developed under EPBD compliance requirements. Testing was developed between 2012–2017 using the standardised Blower Door pressurisation technique. The main purpose of this research is to present a wide-ranging, exhaustive study on the airtightness performance of social housing built in southern Spain; these properties are representative of other locations in southern Europe due to both to their climate conditions and their socio-economic and cultural component. The general performance of the housing stock in terms of normalised permeability at 50 Pa shows a mean value of 7 h⁻¹, similar to that found in other areas in Southern Europe, although with very significant variability between properties which are airtight and those which are highly permeable, all within a housing stock which is similar in terms of type and construction. Based on this information, it has been possible to develop a representative probabilistic description of the housing stock. The study provides useful information on the influence climatic location of buildings as well as age and other and other morphological and constructive parameters of residential buildings.