Analysis of A Wooden Structure Damaged in a Fire – The Wooden Granary at Zaprice, Kamnik

Zaprice Open-Air Museum in Kamnik, Slovenia, features several granaries dating to the early 19th century, forming part of the national Cultural Heritage Register (EID: 1-09881). One of the two-chamber wooden granaries, constructed in 1828, suffered significant fire damage in December 2024. The objective of this study was to evaluate the extent of the damage, assess the structural integrity, and identify appropriate restoration strategies. The investigation combined in-situ and laboratory analyses, including 3D scanning, resistograph profiling, moisture mapping, and material characterization by microscopy, hyperspectral imaging, and X-ray fluorescence (XRF). The fire originated in the roof corner, causing thermal degradation, pyrolysis, and charring up to several millimetres deep. The wood was identified as Norway spruce (Picea abies), with an average density of 418 kg/m3. Flexural strength (MOR = 52.9 MPa) and stiffness (MOE = 7.23 GPa) were approximately 30% lower than reference values for undamaged spruce. Hyperspectral imaging revealed that pyrolytic alteration extended beneath the char layer, indicating structural weakening. Moisture content remained elevated (up to 38%) due to water used during firefighting, posing a risk for fungal colonization. The results highlight the need for careful drying, consolidation, and potential replacement of critical elements. This interdisciplinary assessment demonstrates the value of combined NDT and advanced spectroscopic tools for post-fire diagnostics of heritage wooden structures.