This paper presents evidence in support of the claim that Latin played a significant role as a ‘roof language’ in the languages of western Europe. It focuses on the role that Latin played at three stages of the development of the perfects in western Europe: first, as a conduit of the ‘sacral stamp of Greek’ in bible translation and as influential in other ecclesiastical contexts; secondly, through the influence of scribal tradition and the establishment of the ‘Charlemagne Sprachbund’; and, finally, as a model for classicized syntactic style of the Late Middle and Early Modern period, as exemplified by the patterns of perfect use by the translators of Boethius, especially Chaucer and Elizabeth I. Several larger generalizations also emerge from this investigation: evidence is provided for the stratified nature of Latin syntactic influence across time and space, and the effect of this recurrent replication on the temporal-aspectual systems of the western European languages. Above all, this analysis underlines the essential role of calquing in superstrate-induced change, the structural patterns that are most frequently affected, and the social motivations that foster this type of innovation.