In this work, we propose a new four-node shell element (called BKWH24) with six degrees of freedom per node based on the first-order shell theory of Reissner–Naghdi. The element is valid for thin to thick shells, taking into account membrane, bending, and transverse shear effects with strain components explicitly linear in the thickness coordinate. The BKWH24 shell element is based on the generalisation of the plate-bending BKWA element regarding the approximations of displacements, rotations, and shear strains. The paper presents results for several classical benchmarks for shells and proposes new benchmarks to demonstrate the influence of transverse shear effects in thick shells. © 2025 John Wiley & Sons Ltd.