A particular roof is that of S.M.Maggiore church in Cogoleto. The 19th century church, in fact, has an upper two-pitches roof and a lower roofbelow with a curvilinear profile. Both of them insist on the same perimeter, but they have no direct connection between them as far as it is visible. The study, therefore, focused on the understanding of this part of the building. The understanding of the building was obtained thanks to the use of both indirect sources (archive and bibliographic research) and direct sources: archaeological analyses (stratigraphic, mensiochronological, mineralogical-petrographic and wall textures), thermographic and ultrasonic analyzes. A particular effort had to be made in studying the details and reading the stratigraphic signs on the wood (this aspect is usually little developed). It was necessary to extend the analysis to the entire building for a better understanding. This study highlights a sequence of interventions in the church over the past two centuries; previous structures were usually preserved; new elements and stratifications were added. The two structures were chronologically different: the upper one is the most recent but was designed to preserve the older one below. Another interesting fact that emerged is the particular shape of the lower structure: a wooden roof with a curvilinear profile. This form of coverage is not particularly widespread in this part of the Ligurian territory. In any case, it is unusual for the historical period in which it was built (19th century). The research, therefore, focused on the reasons for this particular choice and the study of the dynamics of the 1877-78 construction site. It also allowed us to understand better the functioning of this specific structure, its technology, and its relationship with the remaining parts of the complex. The historic curved profile roofs highlighted differences in material and installation technique.