How to Install Gutters in 7 Steps

Walk the side of the house with the tape and write down the total length of each run. Gutter comes in 10-foot sections, so a 23-foot run is two sections plus one splice. Pick where the downspout drops - usually a corner near a downhill landscaping bed, never over a walkway. The water has to flow toward that drop, so the far end is the high point and the downspout end is the low point. Watch at 11:20. Sketch the run on paper, mark an arrow on each section in Sharpie pointing toward the downspout end, and pre-cut everything to length before you climb the ladder.

The end cap is what stops water from spilling out the closed end of the run. Slide the cap over the gutter end, hold it flush, and drill four 1/8-inch holes through the cap into the gutter lip - two top, two bottom, one front. Pop a rivet in each hole with the rivet gun. Then run a continuous bead of GS121 sealant in the groove on the back side of the cap before you set it. Watch at 3:00. Smooth the bead with a wet finger so it is one solid line, no gaps. After the rivets are in, run a second interior bead all the way around the seam from inside the gutter.

Long runs need a splice every 10 feet. Skip the splice kit at the store and do this instead. The upstream section drops down into the downstream section so water flows through the joint without leaking. Mark 6 inches in from the cut end of the downstream piece. Cut the outer lip off that 6-inch flap with snips so the upstream section can sit on top. Watch at 6:00. Slide the two sections together until the 6-inch overlap closes up flush, then drill four pilot holes through the overlap and pop rivets through them. Two heavy beads of sealant go between the layers before you rivet, plus one final bead down the inside seam.

The downspout drops through a round or oval hole in the bottom of the gutter. Set the drop outlet on the bottom of the gutter where you want the downspout - typically 4 to 6 inches in from the end cap. Trace around the inner ring with a Sharpie. Drill a 3/8-inch starter hole inside the traced line, then work the snips around the line and pop the disc out. Watch at 8:20. Do not worry if the cut edge is rough - the drop outlet flange will cover it. Test-fit the outlet and trim the hole a bit at a time if the outlet does not seat flush.

Run a continuous bead of GS121 around the underside of the drop outlet flange, drop it into the hole, and press it flat. Drill four holes through the flange into the gutter and pop a rivet in each. Watch at 10:05. Inside the gutter, run one more bead all the way around the outlet flange where it meets the gutter floor and smooth it flat. This is the most-leak-prone joint in the whole run, so do not skimp on sealant here. Let the assembled section sit overnight in a warm spot before you carry it outside.

Hidden hangers clip under the front lip of the gutter and screw through the back wall into the fascia. They are the only thing holding the run up, so the spacing matters. Mark a hanger location every 24 inches along the back wall of the gutter from inside the cabinet. Watch at 11:30. Snap each hanger over the outer lip and slide it down until the back tab sits flat against the gutter back wall. The screw goes through that back tab into the fascia board. Pre-installing the hangers on the ground saves you balancing them on a ladder later.

This is the two-ladder part. Set the high end first. Drive the first hanger screw into the fascia 1/8 inch above your level mark - that single screw holds the run while you work down the line. Your partner on the second ladder supports the far end so the gutter does not bow. Move down the run, driving one hanger screw at a time and stepping the slope down a quarter inch every 10 feet. Watch at 12:30. Once the run is up, pour a bucket of water in the high end and watch it flow to the downspout. Standing water anywhere means a sagging hanger - back the screw out, raise the gutter slightly, and drive it again.