Roller shutter boxes are essential components of building facades, providing crucial thermal and acoustic insulation. Conventional laboratory tests have been traditionally used to evaluate the sound transmission of roller shutter boxes. However, these tests can be expensive and lack repeatability and reproducibility, especially in the low-frequency range. To overcome these limitations, this study aims to introduce an advanced numerical model capable of accurately predicting the vibroacoustic response of roller shutter boxes and optimizing their acoustic insulation performance. The proposed numerical approach utilizes the finite element method to model the various solid and fluid domains within the roller shutter box structure. To capture the behavior of the poroelastic layers, a mixed displacement–pressure formulation of the Biot poroelasticity equations is employed. Excitation of the structure is achieved using a diffuse field comprising a superposition of plane waves with random phases and directions, while the resulting sound radiation is computed utilizing the infinite elements method. To validate the proposed numerical model, a comparison is made with results obtained from laboratory tests, and the experimental protocol is thoroughly described. The practical application of the proposed numerical method extends to the investigation of several influential factors on the acoustic behavior of roller shutter boxes, including assembly conditions, the positioning of poroelastic layers, and the inclusion of heavy masses.