Footings for steel concentrically braced frames are a major contributor to the overall cost of the seismic force-resisting system (SFRS). In general, there are two approaches to design a footing for earthquake loads. Approach 1 involves designing the footing to resist the capacity of the SFRS. Alternatively, Approach 2 entails designing the footing to withstand the design seismic load, which has been reduced from the elastic earthquake demand in accordance with the ductility of the SFRS. The second approach can produce much smaller footings than the first approach, but considering the overstrength of the SFRS, it is likely that the real seismic demands on the footing and underlying soil will exceed the design demands. As such, the size of the footing is an influential factor in the response of the buildings. Additionally, to reliably predict the seismic behaviour of buildings, it is important to consider the inherent uncertainties in the system. Consequently, it is necessary to investigate how different footing sizes affect the building's performance while taking into account both system uncertainty and record-to-record variability. In this study, a 2-storey concentrically braced frame (CBF) building with an X-bracing configuration is selected to study the effects of footing size on the behaviour of the building. This building is located in Vancouver, Canada, on a site Class D condition. The superstructure is designed following the requirements of the Canadian design code and standards, while the footing size is bounded between the most conservative Canadian approach (Approach 1 above) and the least conservative American approach (Approach 2). An advanced computational model, including gravity framing, is developed in OpenSees, and the seismic performance is assessed through nonlinear response history analysis. The uncertainty of the system parameters, including the properties of the superstructure and substructure, as well as uncertainty in the seismic demand on the building, is accounted for using Latin hypercube sampling. The findings of this research suggest the potential for finding an efficient footing size for Canadian low-rise CBF buildings that achieves desirable seismic performance without undue construction cost.