Dear Jitendra
In my view the old method is also very good but in this you or your repersentative should watch the work because some time to save material, labor/ contractor dilute the bitumen by adding old black oil and save material and labor.Secondly you should purase the material your self and do the work with labor.
Care should be taken that no space is left without treatment i.e. if there are pin holes etc that do the area after one or two days. Before doing the process there should be no any dust on the wall.