Disaster mitigation and building code improvements are a major focus of modern wind engineering. While wind tunnel experimental work is a critical tool for the evaluation and development of building standards and codes, time and cost constraints limit its use in industry practice, particularly in low-rise design. One key example of this is the lack of evidence-based knowledge on the impact of building shape on the Main Wind-Force Resisting System (MWFRS). This is particularly overlooked for low-rise buildings, which are typically defined as those with a height-to-width (smallest horizontal dimension) ratio smaller than 1. Despite the prevalence of non-rectangular structures found in practice, guidelines for considering the MWFRS loads on low-rise irregular building shapes are not commonly found in design standards or building codes. Mathematical methods do exist to evaluate wind loading on non-rectangular structures; however, these are often too complex and time-consuming to be properly implemented in industry practice. The objective of this research is to present a comparison between boundary layer wind tunnel testing and the existing mathematical methods for determining wind pressures on irregularly shaped buildings, such as Cook’s Method and the inscribed method. The primary focus is on a range of T- and L-shaped building configurations with both vertical and horizontal irregularities. Six different modular rectangular shapes with different depth, height, and width ratios are combined to form a total of twenty-six models, which are analyzed using each method. This analysis identifies incompatibilities between predicted and actual MWFRS loads with the aim of applying this information to propose a simplified method for determining wind pressures on irregular shapes.