The wood is a material widely used for several purposes, especially in the construction industry. There are many factors that this is due, between them the versatility and abundant availability of the material. However, the intensive use of some species might cause shortages. The lack of information about the wood behavior when it is exposed to various conditions, as well as projects not supported by regulatory rules, may imply in its inappropriate use, compromising in the safety of the structure. In this context, it was proposed the elaboration of roofing structures projects with the following characteristics: lattice type buildings "Howe" (10° slope -cement tile); span of 8, 10, 12, 14, 16 and 18 meters (geometrical proportion, in design, surrounding a 1: 3); typology of the lateral side of the building openings -relations 1:1, 2:1, 6:1 and open (coverage of small dimensions' support) preservative treatment. Then, was determined the ratio of the wood amount (m³) and the built area (in design) to woods of C20 and C30 classes, following the requirements of NBR 7190: 1997. Front of the analysis of results was evidenced that it is possible to use unconventional woods applied in triangle framework structure in big spans, obeying a well elaborated conception of project.