Joining metal gutters together is a process that you can do with a pop rivet gun and some gutter sealant. Allowing an overlap between the sections gives you the ability to join the metal gutters together, while providing a uniform look for the installation. You can join the sections together in just a few minutes and have your metal gutters ready to install. Always be mindful of the sharp edges on the metal gutters when using tin snips.
Cut the ends of the gutter sections to fit the roof line with tin snips, allowing a 4-inch overlap between the gutter sections.
Place a layer of gutter sealant along the inside of one of the gutter sections with a caulking gun about two inches from the edge of the section.
Put one of the gutter sections inside the other section with a 4-inch overlap and press down to allow the sealant to adhere to the sections.
Fasten the sections together about 1/2-inch from the overlap with a pop rivet gun, using two rivets on the bottom and two rivets each on both sides of the gutter.
Spread a thin bead of gutter sealant along the inside edge of the overlap at the end of the section to prevent any leaks between the sections, and place a dab of sealant over each of the pop rivets.