A device for sealing seams between adjoining sheets of flooring (12, 14) comprising: a handheld seam sealing welding gun having a body defining a longitudinal axis of welding gun alignment and having a front heating element end and an opposite rear operator gripping end, a sealant dispensing tip mounted on said front heat welding element end of said body, a roller mounting structure having opposing ends wherein said roller mounting structure is formed as an inseparable part of said rear operator gripping end of said welding gun body, and said roller mounting structure defines an axis of roller rotation, a seam follower oriented perpendicular to said axis of roller rotation, wherein said seam follower together with said longitudinal axis of welding gun alignment define a welding gun equilibrium plane that is perpendicular to said adjoining sheets of flooring (12, 14) when said welding gun is operated to dispense sealant between said adjoining sheets of flooring (12, 14), and rollers (40, 42) mounted on said opposing ends of said roller mounting structure equidistant from said welding gun equilibrium plane, and said rollers (40, 42) are disposed on said roller mounting structure for rotation about said axis of roller rotation, characterized in that the seam sealing welding gun is portable and weighs no more than about 10 pounds (4,54 kg) and is small enough to be lifted and manipulated for operation with only one hand, and the device for sealing seams further comprises an electrically driven propulsion system with an adjustable speed switch for driving said rollers (40, 42) in rotation to travel along said adjoining sheets of flooring (12, 14) in a direction away from said sealant dispensing tip at a speed set by said manually adjustable speed switch. a handheld seam sealing welding gun having a body defining a longitudinal axis of welding gun alignment and having a front heating element end and an opposite rear operator gripping end, a sealant dispensing tip mounted on said front heat welding element end of said body, a roller mounting structure having opposing ends wherein said roller mounting structure is formed as an inseparable part of said rear operator gripping end of said welding gun body, and said roller mounting structure defines an axis of roller rotation, a seam follower oriented perpendicular to said axis of roller rotation, wherein said seam follower together with said longitudinal axis of welding gun alignment define a welding gun equilibrium plane that is perpendicular to said adjoining sheets of flooring (12, 14) when said welding gun is operated to dispense sealant between said adjoining sheets of flooring (12, 14), and rollers (40, 42) mounted on said opposing ends of said roller mounting structure equidistant from said welding gun equilibrium plane, and said rollers (40, 42) are disposed on said roller mounting structure for rotation about said axis of roller rotation, characterized in that the seam sealing welding gun is portable and weighs no more than about 10 pounds (4,54 kg) and is small enough to be lifted and manipulated for operation with only one hand, and the device for sealing seams further comprises an electrically driven propulsion system with an adjustable speed switch for driving said rollers (40, 42) in rotation to travel along said adjoining sheets of flooring (12, 14) in a direction away from said sealant dispensing tip at a speed set by said manually adjustable speed switch.