Structural and health assessment of historic timber roofs from the Convent of Christ in Tomar

Before coming up with any important decision of intervention in the restoration process of existing buildings, the assessment of the conservation state is required as regards heritage timber structures and especially for those that suffered a lack of maintenance in their service life. In that context, three timber roof structures from the Convent of Christ in Tomar, Portugal, were selected and investigated. To this end, a research methodology was introduced and applied to these case studies into four main steps: (1) visual inspection; (2) non-destructive wood diagnosis; (3) structural safety evaluation; (4) prevention and intervention measures. For the visual inspection, every element and joint constituting the roof structures received scrutiny through assessing the wood species, the different construction stages and, last but not least, their respective geometry. As regards the encountered pathologies, structural disorders (e.g. accidental failure, serviceability defects…) and wood deteriorations due to biological agents (e.g. wood-destroying fungi or insects), which ineluctably leads to a likely decrease of the mechanical performances of the roof structure, were reported. To estimate the residual element cross section and elastic modulus, wood diagnosis was carried out using three relevant non-destructive tests: (1) ultrasonic pulse velocity; (2) drilling resistance; (3) impact penetration. From the collected data, the three timber roof structures were modelled on a commercial software to check their safety and integrity. Based on those outcomes, some prevention and intervention measures haves been lastly proposed case by case.This work was financed by FEDER funds through the Competitively Factors Operational Programme—COMPETE and by national funds through FCT—Foundation for Science and Technology within the scope of the research project INVISIBLE WOODS PTDC/EPH-PAT/2401/2014, and the PhD Scholarships SFRH/BD/128580/2017. Besides, we would also like to acknowledge Prof. Cristina Nabais, from the University of Coimbra, for her collaboration dealing with the dendrochronological part and, last but not least, the DGPC for opening the doors to the wonderful Convent of Christ in Tomar and for the permission to investigate the timber roof structures in the dormitory Room 68 and Knights’ Hall