The effectiveness of WUI fuel management practices aimed at protecting communities, infrastructures, and homes is analysed, specifically considering prescriptions for shaded fuel breaks of the regions of Catalonia (Spain) and Pyrénées-Orientales (France). Fire spread through fuel breaks is simulated under different environmental and wildfire exposure conditions in FDS (Fire Dynamics Simulator). The French regulated fuel breaks are simulated as 50 m wide areas with a density of 600 trees/ha, and the Catalan regulated breaks as 25 m wide areas with 300 trees/ha. The analysis allows a quantitative comparison of the fire protection provided by different fuel management regulations. Results show that the analysed shaded fuel breaks meet the objective of modifying fire behaviour and reducing emitted heat fluxes and temperatures, although, in some cases, not sufficiently, thus exposing assets to untenable environments, with possible direct flame contact or exposure to high heat fluxes and temperatures. Analysed scenarios also highlight that tree density within the fuel break can impact fire spread through surface fuels. Obtained results show that a 25 m wide break, as the one from the Catalan regulations, is not sufficient in several scenarios; additionally, when exposed to high wind speeds (7.8 m/s), a 50 m wide fuel break (French regulations) is also insufficient.