PSI - Issue 81

Andrii Pavluk et al. / Procedia Structural Integrity 81 (2026) 198–204

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a)

b)

Fig. 5. Infestation of timber elements by wood-boring insects: a) service life from 10 to 50 years; b) service life over 50 years.

Timber decay (rot) was also detected as a defect (Fig.6). This defect appeared exclusively in roofs with a service life of more than 10 years, and its cause was leakage of the roofing layer. a) b) c)

Fig. 6 Timber decay in roof structural elements: a, c) service life from 10 to 50 years; b) service life over 50 years.

Another common defect was corrosion of metal components in connection joints (Fig.7). As the timber elements aged, the area and depth of corrosion increased correspondingly. a) b) c)

Fig. 7 Corrosion of metal components in the joint connections of timber roof structures: a) service life from 10 to 50 years; c) service life over 50 years.

Several timber elements also exhibited charring as a result of previous fire exposure (Fig. 8). This defect was found on three out of fifty roofs examined. a) b) c)

Fig. 8. Charring of timber elements due to fire exposure (a, b, c). In addition, a number of technological defects were recorded, including the absence of a waterproofing membrane, discharge of ventilation ducts into the attic space, and other violations of regulatory requirements (Fig. 9). It should be emphasised that when ventilation ducts open into the attic, the timber elements located above them deteriorate very rapidly. Moreover, corrosion of the