A roof mounting system for attaching at least one PV module to a roof, the system comprising: (a.) a roof having a roof surface; (b.) a plurality of base mount assemblies , each of the plurality of base mount assemblies comprising: (i.) a base member having a first surface adjacent the roof surface and a second surface opposite the first surface, wherein an upstanding projection is connected to and extends away from the base member , the upstanding projection comprising a distal end having a distal end aperture; (ii.) a block member comprising a substantially horizontal portion and a vertical engaging portion , wherein the substantially horizontal portion has a borehole formed therethroughconfigured to receive the upstanding projection ; (iii.) a tightening means inserted through said borehole and distal end aperture, the tightening means attaching the block member and base member to the roof, the tightening means having a long portion and a head portion; and (iv.) a sealing washer between the head portion and the upstanding projection distal end, the sealing washer comprising a steel disk contacting the head portion and a deformable part contacting the distal end thereby forming a waterproof seal; and (c.) at least one PV module coupled to at least one of said plurality of base mount assemblies , the at least one PV module having a mounting height; and (d.) a sliding member having a sliding groove mating with the vertical engaging portion to adjust the at least one PV module mounting height. (a.) a roof having a roof surface; (b.) a plurality of base mount assemblies , each of the plurality of base mount assemblies comprising: (i.) a base member having a first surface adjacent the roof surface and a second surface opposite the first surface, wherein an upstanding projection is connected to and extends away from the base member , the upstanding projection comprising a distal end having a distal end aperture; (ii.) a block member comprising a substantially horizontal portion and a vertical engaging portion , wherein the substantially horizontal portion has a borehole formed therethroughconfigured to receive the upstanding projection ; (iii.) a tightening means inserted through said borehole and distal end aperture, the tightening means attaching the block member and base member to the roof, the tightening means having a long portion and a head portion; and (iv.) a sealing washer between the head portion and the upstanding projection distal end, the sealing washer comprising a steel disk contacting the head portion and a deformable part contacting the distal end thereby forming a waterproof seal; and (i.) a base member having a first surface adjacent the roof surface and a second surface opposite the first surface, wherein an upstanding projection is connected to and extends away from the base member , the upstanding projection comprising a distal end having a distal end aperture; (ii.) a block member comprising a substantially horizontal portion and a vertical engaging portion , wherein the substantially horizontal portion has a borehole formed therethroughconfigured to receive the upstanding projection ; (iii.) a tightening means inserted through said borehole and distal end aperture, the tightening means attaching the block member and base member to the roof, the tightening means having a long portion and a head portion; and (iv.) a sealing washer between the head portion and the upstanding projection distal end, the sealing washer comprising a steel disk contacting the head portion and a deformable part contacting the distal end thereby forming a waterproof seal; and (c.) at least one PV module coupled to at least one of said plurality of base mount assemblies , the at least one PV module having a mounting height; and (d.) a sliding member having a sliding groove mating with the vertical engaging portion to adjust the at least one PV module mounting height. <EOS>