Things You'll Need
Most gutters available for do-it-yourself installations come in several pieces you must cut to fit, then assemble. To attach the pieces, you must use a slip joint, a small strip of gutter material that wraps around both gutter pieces and seams them together. While gutters can be connected before hanging, it often is easier to first hang the gutters, then install the slip joints.
Place the top lip of the slip joint's back over the top of the rear edge of the two gutter pieces. Align the slip joint so it fits evenly over both sections of gutter.
Wrap the slip joint around the outside of the two gutter pieces. Place the top lip on the front of the slip joint over the front edge of the gutter pieces. Pry open the top lip on the slip joint with your fingers if necessary to get it to fit around the gutter pieces.
Apply a bead of sealant on the inside of the gutter, between the ends of the gutter pieces and the slip joint.
Wait 24 hours for the sealant on all the installed slip joints to dry.
Run water down the gutter and observe each joint for leaks. Dry the area and apply more sealant if necessary.