Setup: Measure Your Gutter Draw a diagram of the gutter system and layout, plan where downspouts will go. Measure the overall distance that your gutter will run for each section and write the distance in your diagram. TIP: Don't forget to a 6" Inches to the length for an outside corner, It's safest to add a foot to each length when cutting your gutter to compensate for the corners. Remember you can't stretch metal but you can shorten it. Step 1: Snap layout lines Mark a line for the highest point of the gutter run on the fascia 1 inches below the metal drip-edge or flashing. At the other end of the fascia or at the downspout location if there's one in the middle of the run, mark the low end of the gutter and note that the slope should be approximately ½ inch for every 10 feet of run. Snap a chalk line between the two points. Tip: Check the for rot and make any repairs if before installing the gutter system. Step 2: Prep the roof line Locate the rafter tails behind the fascia; they're typically spaced 16 inches on center look for nail heads sticking out or anything that will stop the gutter from laying flat on the roof. Make a mark at the chalk line on every other rafter tail, so you know where to screw the gutter in. Some Drill a ⅛-inch-diameter pilot hole through the fascia and into the rafter tail at each mark. TIP: Rub soap on the lag screws so they'll be easier to drive through fascia and into rafter tails. Step 3: Cut gutter to length Cut gutter section to length with aviation snips, or with a 12-inch power miter saw fitted with a carbide-tipped finish blade. If the gutter continues around a corner, cut the appropriate angle (typically 45 degrees) on that end. If the run requires two sections of gutter, overlap them by 8 inches and use 3/8-inch-long, self-tapping, stainless steel screws or pop rivets, in two rows of four each, to join them. Tip: Locate screws or rivets in all sides of the gutter. Step 4: Attach end caps At the square-cut end of the gutter, attach an end cap with pop rivets or end cap crimps. To do this, hold the end cap in place temporarily with a single sheet-metal screw, then drill a 1/8-inch-diameter hole and install one pop rivet. Remove the temporary screw and replace it with a rivet. TIP: To ensure a watertight joint, seal the rivets and the end-cap seam on the inside of the gutter with a high-quality caulk. Step 5: Cut downspout holes Use a downspout outlet to mark the location of the downspout on the low end and bottom of the gutter. To do this, turn the gutter upside down and place the outlet on top. Trace around the inside of the outlet to mark the downspout hole on the gutter. Drill a ¼-inch-diameter hole through the center of the circular outline. Turn the gutter over and cut the downspout hole using a 2-inch-diameter hole saw chucked into a drill. Step 6: Install gutter Lay the gutter onto the roof that you've marked, and rotate the gutter upward until its back edge slips under the roofing material. Through the screw-mounting hole in each bracket, drill a 3/16-inch-diameter hole in the front edge of the gutter. Secure the gutter to the bracket with a 1-inch-long #8-32 stainless steel machine screw and fanged nut. TIP: Gutters and brackets or hangers can be spray-painted to match or contrast with the house trim. Step 7: Connect downspout to gutter Secure the downspout outlet to the gutter with four pop rivets or screws. Screw a downspout elbow to the outlet tube protruding down from the gutter. Hold another elbow against the house and cut a piece of downspout to fit between the two elbows. Use needle-nosed pliers to slightly crimp the elbow to fit into the downspout. Fasten the parts together with pop rivets or screws. TIP: Use two downspout brackets on a one-story house and three brackets on a two-story house.