In this work, an experimental procedure was conducted to investigate the effect of weight content of short E-glass fibers on the degradation of flexural properties of a hybrid building material, when exposed to a direct gas (propane/butane) flame for varying time intervals. This experimental procedure is aiming on one hand to define the role that E-glass fibers play on the degradation of the flexural properties of the materials tested, as well as to provide a sufficient quantity of experimental data which will allow to quantitatively predict the observed degradation of the aforementioned properties due to exposure to direct gas flame using the Residual Property Model (R. P. M.) developed by the first author and already successfully applied to a number of different materials subjected to a combination of different damage sources. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2724-2731, 2013