A preliminary anthraco-entomological study of the charred woods of Notre-Dame de Paris (France): Towards an assessment of the degradation state of medieval and modern-day roof frames based on woodborer traces

Abstract

The terrible blaze of Notre-Dame de Paris cathedral on 15 April 2019 fostered the gathering of an important consortium of researchers, especially on the subject of timber, through ANR project CASIMODO (coord. A. Dufraisse, MNHN, BioArch UMR 7209). Characterisation of the bio-infestations of the roof frame was one of the many lines of research that ensued from the blaze. Notre-Dame de Paris is admittedly free of any attack by woodborers. Yet, this only reflects the absence of studies on the subject, apart from a few annotations on the architectural surveys of the main trusses carried out by R. Fromont and C. Trentesaux (2015). The aim of the present article is to propose a first overview of infestations of medieval and modern-day roof frames by pests (woodborers and lignin-degrading fungi) through the observation of 821 pieces of timber. The impact of recurrent infestations of the underside of the lower pieces of trusses (wall plates and truss beams) provides evidence of insufficient imperviousness of the building. The resulting water infiltrations drenched the wood and allowed for the settlement and the development of 11,580 insects. The longevity of this structure – nearly 800 years for some pieces – makes it tricky to date back and understand these infestations and gives rise to several questionings, particularly on the methodological aspects of the anthraco-entomological approach.