This book deals with the analysis of the forces acting in bracing of triangular timber trusses of warehouses roofings by computational numerical models based on the Finite Element Method (FEM). Were used the structural analysis software STRAP and consider the operation of bracing in the three-dimensional structure. The maximum force values obtained in the three-dimensional models were compared to the minimum values indicated by the estimation method of the Brazilian standard ABNT NBR 7190:1997, which is based on the lateral instability of the braced element. The values of three-dimensional models are also compared to the methods of Eurocode 5, the South African Standard SABS 0163 and the values proposed by UNDERWOOD (2000), by presenting a similar formulation to the NBR 7190:1997. The models represent usual warehouses with dimensions ranging from 12, 18 and 24 meters wide, 24, 48 and 96 meters length, and 3, 4 and 6 meters column heights. In this context, were analyzed the trusses types: Pratt and Howe, the timber classes: C30 and C50 and the roof types: fiber cement, metal sheets and ceramics tiles ¿ materials most used in Brazil.