An investigation based on I-Beam models was undertaken in this paper for extending knowledge regarding the flexural modulus of structural foam. The applicability of five I-Beams models (I-Beam A, B, C, D and E) including a newly developed one (I-Beam E) were investigated in this work. The square law model was used to predict Young's modulus of uniform density foam, which was subsequently utilized for the calculation of the I-Beam models. I-Beam A, B and E were observed from the configuration analysls of each I-Beam to be the more suitable models for predicting the flexural modulus of the structural foams having either an integral skin or a skin with limited residual bubbles, among which I-Beam E is considered to be better than I-Beam B and A. The comparison of the experimental and theoretical values of the flexural modulus of the structural foams molded with gas counter pressure structural foam (CPSF) and low pressure structural foam (LPSF) molding methods also confirmed that the newly developed I-Beam E is the most adequate model for predicting the flexural modulus of structural foams having either an integral skin or a skin with few residual bubbles. I-Beam B and A were also demonstrated to be in good agreement with the experimental data.