Abstract In design, the global response of a T-system timber bridge is reduced to the analysis of a T-beam section. However, no guidelines exist for the analysis of the transverse deck behavior. This paper presents design equations for the computation of the maximum local transverse deflection and stress in a deck section between two adjacent stringers. The design equations are obtained through a finite element parametric analysis of 41 bridge models subjected to AASHTO truck wheel loads. The proposed design equations are compared to a closed-form series solution and are verified with experimental results obtained for two bridges currently in service.