Abstract: A device for heating the bitumen layer of rolled roofing material in such a way that said layer becomes soft and sticky enough to adhere to the surface to be covered without burning said layer, comprising a distributing pipe (19) with many small closely distributed burner nozzles (20) for a combustible gas placed inside an elongated boxlike casing (9). The burner nozzles (20) form a row (10) inside the casing which is open at the front and rear. The plates (13, 14) and its width is considerably greater than its height while its length is considerably greater than its width. The distributing pipe (19) runs between the gable plates (13, 14) and is so positioned between and parallel to the top and the bottom plates that air slits (21, 22) are formed between the pipe and the top (11) and bottom (12) plates, respectively, said slits admitting air from the rear (17) of the casing to the nozzles (20).