A computational multi-scale framework is proposed for the representation of the complex non-linear behaviour of planar masonry structures. The average response of the masonry material is deduced from a unit cell through scale transitions with specific periodicity requirements. A standard continuum approach is used at the macroscale. Finite width damage localization bands with a mesostructurally motivated width are introduced in the macroscopic description. Localization detection is based on the homogenized acoustic tensor analysis. Macroscopic localization along preferential orientations is detected in a consistent way with the underlying mesostructural failure patterns and with the applied loading. As a result of the use of homogenization techniques on finite volumes, mesostructural snap-backs may occur in the homogenized material response. A methodology to introduce this type of response in the originally strain driven scale transition is proposed. The framework is applied to examples showing the numerical robustness of the method.