Damage or collapse of buildings where traditional timber roof structures had been removed and substituted with new ones of different material and typology have recently suggested to adopt less invasive strengthening techniques, maintaining the original structure but reducing its seismic vulnerability. The characteristics that may affect the seismic response of timber roof structures and that may be taken as vulnerability indicators are: the presence of unrestrained thrusts; the condition of the supports connecting the roof to the underlying structure; the conceptual design of the structure; the type and condition of carpentry joints; the size and condition of timber elements; and the general state of conservation. According to the vulnerability assessment method discussed here, after a visual inspection of the structure each indicator is classified according to a specific vulnerability scale. The set of indicator values obtained offers a measure of the global vulnerability level of the structure and points at the specific deficiencies of the system, for which seismic strengthening may then be considered