Set the ladder up against the wall to gain access to the roof. Be sure to place the ladder feet properly on a solid surface so that it does not slide. Remove the old roofing material, using a shovel to assist. Remove any remaining nails using the claw end of a hammer. Sweep the roof thoroughly after you have all of the old roofing material off. Anything left on the roof will poke through the new roofing material and create new leaks when the project is complete.
Install metal flashing around the edges of the roof, using a hammer and roofing nails to secure it. Be sure to overhang the roof at least 1/2 inch. Cut the flashing to the proper length using a pair of tin snips. Cut enough strips 18 inches wide from the roll roofing for starter strips around all of the edges of the roof. Spread roofing cement around all of the outer edges of the roof, using a large paint roller affixed to a roller handle.
Place the 18-inch sections along the outer edges of the roof and nail them in place using a hammer and roofing nails. Be sure that the starter strips hang over the edges of the roof about 1/2 inch. Unroll a section of roofing felt and cut it to the length of the first run using the utility knife.
Place the felt at the outer edge of the roof covering the starter strip. Nail it into place using a hammer and roofing nails. Repeat the process for the next section of roofing felt. Overlap the first section by 3 inches and nail it into place. Continue the process until you have the entire roof covered with the roofing felt.
Unroll the GAF Mineral Guard roll roofing and cut a section equal to the length of the roof, using the utility knife. Place this section of roofing over the roofing felt and nail it into place using the hammer and roofing nails. Place a nail about every 3 inches when securing the roll material to the roof.
Cut the next section of GAF Mineral Guard roll roofing with the utility knife. Place it on the roof and overlap the first section by 3 inches. Nail the roofing into place with the hammer and roofing nails. Continue the process until the entire roof is covered.
Spread roofing cement over the nail heads and all seams, using the paint roller and handle, starting at the point farthest away from the ladder and working your way back.