Residential development in forested areas increases the wildland-urban interface (WUI); in this area, wildfires are the primary conflict for humans and ecosystems. The methodologies to determine the WUI use dwellings location and vegetation fuels. The main difference in the WUI mapping has been the application of housing density limits and the maximum extent from houses into vegetation. Our objectives were to (i) determine the wildland-urban interface using a novel approach in the city of Bariloche, in NW Patagonia, Argentina; and (i) evaluate the relationship between the WUI and fire ignition points. We mapped the WUI based on housing information derived from a recently released building footprint dataset, land-cover data, and a digital elevation model. Our method improves the accuracy of mapping based on local terrain conditions, making it possible to apply it for local management and planning. The determined WUI has higher extension under steep slopes ascending towards dwellings (>20%), where the rate of fire spread is high. In 2021, the wildland-urban interface in Bariloche included 89% of the buildings, even though it occupied 25% (133 km²) of the municipal district. Between 2016-2018, 90% of fire ignitions occurred in the WUI, highlighting the importance of the WUI for planning and management to reduce wildfire risk.