This licentiate thesis examines through three articles the corpus of preserved medieval timber roofs in churches of Västergötland and Northern Småland, based on surveys in the dioceses of Linköping, Skara and Gothenburg 2010–2021. These were the first systematic surveys of medieval roof structures in the regions. The primary aim of this thesis is a typology and chronology concerning the medieval church roofs of the two regions. Focus is put on the High Medieval material of Västergötland, where cross-disciplinary case studies have been made. Systems and techniques applied by the medieval carpenters could be identified, interpreted and structured. These in-depth field studies have together with studies of reference roofs from other regions and countries given a deeper insight into the roof structure and its part in medieval church building. Motives behind technical choices are discussed as well as the extent of possible domestic features. A narrative for Västergötland is sketched, from a pluralistic carpentry in the first half of the 12th century – although part of a European tradition of trussed tiebeam roofs – towards a more normative one. The latter just slowly opened up for new impulses from the continent, due to a decline in church building commissions in Västergötland after the mid-13th century. The uniform character that developed in Västergötland is not at hand in the material of Northern Småland. This thesis also points at the values that can be identified in historic roof structures through cross-disci- plinary fieldwork and how such investigations are necessary in order to maintain and restore an important European heritage in timber.