Traditional restoration and rehabilitation work of flat timber ceilings at historical Islamic buildings in Cairo generally require the dismantling of most of their timber parts (i.e. timber planks, secondary beams, etc.) to expose the timber main beams and conduct the work. Hence, these parts are liable to damage and lose during the dismantling that requires time, money and effort to achieve. Hence, the author conducted this study to overcome the dismantling work and propose effective strengthening techniques for the timber beams utilizing two-layered composite system. This paper reported the limited application of the layered system in the construction of the historical timber beams in Cairo. It studied a number of innovative strengthening proposals of the timber beams from their upper-side merely while leaving the exposed bottom surface intact, apart from its indispensable shoring. Hence, a small experimental and a wide comparative analytical investigation of the strengthening proposals utilizing two-layered composite system are conducted. Several 2D Finite Element numerical models using well-known software were conducted. The modelling techniques of various interfacial conditions of the two-layered beams are established and evaluation of the strengthening proposals is conducted. Finally, conclusions and recommendations are derived.