A technique is presented for modelling lattice-work metallic structures with dimensions in the resonant region of the illuminating radiation. A simple model for the scattering from a single strut is used as the building block for a complete lattice-work structure, giving the spatial distribution of the scattering, and a scale model is used to validate the amplitude normalization for one particular case.The application of the technique to a 45 m tall vent stack is described, where the vent stack was to be constructed in the paths of microwave data and voice links. Measurements at the site in Norfolk after construction of the vent stack are described and clearly demonstrate the effectiveness of the model.