New concepts are addressed for predicting the flame spread on materials from laboratory measurements. It focuses on heat transfer which precipitates and precedes upward flame spread on a vertical surface. Six materials have been featured in this study as well as in past related studies. Their flame spread properties are presented. In this particular study heat transfer and flame height results are presented for wall samples burned at varying levels of external irradiance. Also complementary results are presented for methane line burner wall fires. An approximate theoretical analysis is included to serve as a guide to identifying the important variables and their relationship for correlation purposes. Experimental results yield flame height proportional to energy release rate to the 2/3 power, and wall heat flux distributions are roughly correlated in terms of distance divided by flame height. These correlations appear to at least hold for the scale of these experiments: flame heights of 0.3 to 1.47thinsp;m.