How to Install a Downspout

Installing a downspout is a job most homeowners can handle in an afternoon, and the parts are simple: an outlet that drops water out of the gutter, a run of pipe down the wall, a few elbows to steer it, straps to hold it, and something at the bottom to carry the water away. The order of work is straightforward. What trips people up is not the pipe — it is the last step. A downspout that ends at the base of the wall just delivers the whole roof’s water to the worst possible spot. The discharge is the part people get wrong, so that is where most of your attention should go.

The parts and the plan

Before you cut anything, walk the run in your head from top to bottom. Water leaves the gutter through an outlet (also called a drop outlet), turns back toward the wall through a top elbow or a two-elbow offset, drops down the wall as straight pipe, is held in place by straps or brackets, and turns out at the bottom through another elbow into an extension. That is the whole system.

Pick the spot with care, because placement decides how well everything downstream works. A downspout wants to sit at a low point of the gutter run, at a corner where it is unobtrusive, and somewhere the water can actually be led away at the bottom. Our guide to where to place downspouts covers the trade-offs; the short version is that the best-built downspout in the wrong location still leaves you with a drainage problem.

Step by step

Here is the sequence most installations follow. Times and specifics vary with your house, so treat this as the shape of the job rather than a rigid script.

Step	What you do	Why it matters
1. Mark and cut the outlet	Locate the outlet at a low point in the gutter, trace it, and cut the hole	Sets where water leaves the gutter; a bad spot dooms the rest
2. Fit the top elbow / offset	Attach the outlet, then the elbow or offset back to the wall	Pulls the pipe in over the siding instead of dangling out
3. Measure and cut the drop	Measure wall to ground, cut the straight pipe to length	Too long crowds the ground; too short leaves a gap
4. Assemble the run	Nest each section inside the one below, add the bottom elbow	Keeps water inside the pipe at every seam
5. Strap to the wall	Fasten straps top, bottom, and every few feet	Stops sag, rattle, and pull-away over time
6. Handle the discharge	Add an extension carrying water well away	The step that actually protects the foundation

1–2. Outlet and the turn back to the wall

Start at the top. The outlet drops into a hole cut in the bottom of the gutter, so mark it at a low point of the run and cut cleanly. From the outlet, the pipe has to travel back toward the siding, because gutters hang slightly out past the wall. That is the job of the top elbow, or a pair of elbows forming an offset with a short piece between them. Getting this jog right is what lets the downspout sit flat against the house rather than dangling in mid-air. The full mechanics of these fittings — A-style versus B-style, and which way each bend should face — are covered in downspout elbows and offsets explained.

3–4. Run the pipe down and assemble it

Measure from the bottom of the top elbow down to where the lower elbow will start, and cut your straight pipe to that length with snips or a hacksaw. As you assemble, remember the golden rule of seams: the upper section fits inside the lower one. That way water stays captured inside the pipe. Reverse it and water sheds down the outside at every joint, streaking the wall and sometimes escaping behind the pipe entirely — a small mistake with visible, lasting consequences.

5. Strap it to the wall

A downspout that is not secured will rattle in wind, sag under the weight of water, and eventually pull away from the wall at the fittings. Straps or brackets fix that. A common approach is one near the top, one near the bottom, and one every few feet in between, with extra support on long runs or in windy, freeze-prone regions. You want the pipe to feel solid when you give it a firm push.

6. Get the discharge right

This is the step that justifies all the rest. Left as-is, the bottom elbow drops water right at the base of the wall, into the backfilled soil that sits closest to the foundation — the very soil most prone to holding water and slumping back toward the house. Add an extension that carries the flow out onto ground that slopes away.

How far is far enough? A widely cited starting point is at least four to six feet, but soil, grade, and roof size can all push that number higher. Rather than trust the tape measure, watch what happens in a real storm: if water disperses and moves off, the distance is working; if it pools or trickles back, it is not. Our guide on how far downspouts should extend walks through the options and what changes the answer.

Pros and cons of a DIY install

Common mistakes

• Reversing the seam overlap. Fitting an upper section outside the lower one lets water run down the outside of the pipe, streaking the wall at every joint.
• Skimping on straps. Too few supports and the pipe sags, rattles, and eventually pulls loose at the fittings.
• Stopping at the wall. A downspout with no extension dumps the entire roof’s water into the foundation’s backfill zone — the single most common and most damaging error.
• Guessing the outlet location. Placing the outlet away from a low point means water pools in the gutter instead of draining to the spout.
• Over-complicating the path. Every extra elbow is another place debris catches. Use as few turns as the roofline allows.
• Ignoring where the water ends up. Discharging onto a walkway, toward the house, or across a property line can create ice, puddles, or a dispute. Check local rules before routing water off your lot.

The bottom line

A downspout install is really two jobs stacked together: the pipe work, which is easy and forgiving, and the discharge, which is where the whole effort either pays off or fails. Cut a clean outlet, nest your seams the right way, strap the run solid, and work safely at the top. Then spend your remaining attention on the bottom, carrying that water far enough out that it leaves the foundation alone. Get the discharge right and everything above it is just plumbing.