Structural assessment of existing unreinforced masonry buildings is carried out assuming a well-defined system response with strength capacity derived from the in-plane response of piers, connected together by the box-action provided by spandrel beams and a rigid diaphragm.Rigid diaphragm action, stability of out-of-plane walls and adequate coupling of spandrels areassumed to be availableso that an integral system response is generated. Hence, the accuracy of the capacity estimates is subject to the validity of the aforementioned assumptions. Therefore, recent assessment frameworks have started exploring unreinforced masonry buildings as an assemblage of local sub-systems considering the multiple interactions occurring between these sub-systemsand associated failure mechanisms. This leads to an assessment methodology based on increasing order of vulnerability for the different elements in the lateral load path. A weak link in the lateral load path limits the maximum capacity attainment of a component which in turn reduces the global capacity estimate of the structure. The research presentation focusses on addressing component level interactions in unreinforced masonry structures for refining the existing capacity estimates. This includes characterizing diaphragm response, investigating the effects of diaphragm flexibility in developing multiple interactions and the role of out-of-plane effects in restricting the in-plane pier capacity of masonry piers.