Build the Downspout in Place — and Keep Screws Out of the Water's Path

The Problem

The offset between a gutter outlet and the wall — the dogleg the downspout's top section has to make — generates more measuring folklore than almost anything in guttering. Formulas, subtractions, magic numbers; the installer behind this video says he's heard a hundred versions and watched none of them beat the direct approach. Meanwhile, downspouts assembled with sections backwards or screws in the waterway leak from day one.

The Technique

1. Build the first section in place. Hold the elbow to the gutter outlet and the wall, run your tape in the assembly to see where the cut lands, mark it, and cut. The parts themselves are the measurement — no formula survives contact with a real fascia anyway.
2. Feed each piece into the one below it. Downspout sections are crimped so the upper piece nests inside the lower — water passes joint after joint without ever meeting an edge. Assembled backwards, every joint is a ledge that catches water, and she leaks.
3. Keep screws out of the water's path. Water hugs the low side of every elbow and the bottom of every joint. Drive your screws high on the joint, away from where the flow runs — a screw in the waterway is a hole in the waterway.
4. Strap it twice — two straps hold the assembled run to the wall, and it's locked down.