This paper presents the results of RANS-based numerical simulation of 3D flow dynamics and heat transfer in the turbulent free-convection boundary layer disturbed by a transverse periodic row of finite-height cylindrical obstacles. The disturbing row elements are mounted on a vertical isothermally heated plate along which the free-convection flow develops starting from a 2D state prescribed at the computational domain inlet. The height-to-diameter ratio of the cylindrical obstacles is varied from 1 to 3, and their surface is treated as adiabatic or isothermal. Vortex flow structures and local heat transfer patterns in the front and in the rear of the introduced macroroughness are analyzed.