This paper describes an engineering model of the upward turbulent flame spread along a vertical combustible surface based on a concept of ignition and flame spread as a result of inert heating of the solid to an ignition temperature. Experiments were made by using porous line burners to represent the wall flame heat transfer as a function of heat release rate and pyrolysis length. An exploratory analysis was made to correlate flame spread properties with thermometric material properties based on this model. This analysis seems to be consistent with current experimental work on turbulent wall flames.