Where Your Downspout Empties, and Why It Freezes on the Walk

A downspout that ends a few inches off the front walk looks finished in October. By the first hard freeze in January, it may be the reason the walk is a sheet of ice. In St. Louis, the ground goes through freeze and thaw many times between December and March, and every thaw sends the water from the downspout onto the same patch of concrete. The gutter did its job. The discharge point did not.

Where the water lands in winter

Rain in October runs off a wet roof, down the trough, out the bottom of the downspout, and into whatever is there. Snow and ice behave differently. A downspout that dumps several gallons onto a walk during a thaw can refreeze overnight into a patch that stays for days. Concrete walks in older St. Louis neighborhoods often slope toward the street, so water flows across the walk and pools where the walk meets the curb or the lawn. The path the water takes and the path a visitor takes to the door are often the same path.

Frozen gutters are a separate problem, and this site covers them elsewhere. This page is about the last few feet of the drain, the part where the downspout leaves the house and the water starts moving on its own.

Measuring the discharge on your own lot

Start on a dry day in late October, before the leaves are fully down. Stand at the bottom of each downspout and look at where the water would go during a heavy rain. Note whether it lands on concrete, gravel, lawn, or bare clay. Note the slope. A garden hose works well for this. Run it into the top of the downspout for two minutes, then walk the path the water takes and mark where it stops. If it stops at the edge of a walk or runs toward a door, the discharge needs a change before the first freeze.

Then check the grade at the foundation. Water leaving the downspout should move away from the wall. A flat or backsloped bed against the house holds water against the foundation, and the same water that freezes on the walk can also seep into a basement wall. Our notes on splash blocks and grade cover the clay problem in more detail. The short version is that the discharge should carry water to a point where it can soak in or drain away, and that point should be well away from any path you walk in January.

Extensions, elbows and the length that works

A downspout extension is the usual fix. It is a length of rigid or flexible pipe that attaches to the bottom elbow and carries the water out from the house. Length matters more than material. On most St. Louis lots, a run of four to six feet gets the water past the wall line and beyond the first patch of walk. A short stub that stops at the foundation is the most common mistake, and it is the one that produces the frozen patch on the walk. Flexible corrugated extensions catch debris and can freeze solid at a low point. Where the run crosses a walk, a rigid pipe with a steady drop is usually the better choice.

The elbow at the bottom of the downspout deserves attention too. A tight elbow that points straight down throws the water onto one spot. An elbow angled away from the house spreads it out. Neither one fixes a bad grade, but together with a proper extension they keep the discharge from freezing into a single slab.

Underground options and why they are not a quick fix

Some lots can take the downspout underground to a daylight outlet at the back of the yard, or to a drainage line that runs to the street. That works well when there is a clear route and a place for the water to go. It is not a winter fix. The trench has to be dug, the pipe needs fall, and the outlet has to stay clear of leaves and clay. Our page on underground drainage to daylight covers how those systems fail, and the usual failure is a clogged outlet during the first hard freeze. If the lot has a long way to the daylight point, a rigid extension run across the yard is often the more practical choice for this season.

Gutters and guards

The discharge question affects how gutters and guards perform, because a guard does nothing for the water once it leaves the bottom of the downspout. If you are buying guards, ask whether the downspout outlet will be cleared during the install and whether the guard will let debris reach the discharge. Fine grit that passes a guard can settle in a short extension and clog the end of the pipe. A downspout strainer at the top catches that material before it reaches the elbow. Ask whether the strainer is part of the guard price or a separate line.

Guards also change how water enters the trough. Ask how quickly the guard lets water into the gutter during a cloudburst, because that sets how much water arrives at the bottom of each downspout at once. A downspout that receives a sudden rush of water discharges a heavier flow, and an extension that was fine for light rain may not carry it. Check each discharge after the first heavy rain of the season and see where the water actually lands.

What it costs

An extension is a small part of a gutter job. The materials are inexpensive and the labor is short. The cost question usually comes down to two things: how many downspouts need new discharge lines, and whether the run to the discharge point crosses a walk, driveway, retaining wall, or lawn that will need repair afterward. A quote that says extensions are included should state the length of each one, the material, and whether the bottom elbow is replaced or reused. An underground line should be priced separately, with the trench length, pipe size, outlet type, and yard restoration each listed.

Ask whether the price includes repair of any walk or lawn that the trench or pipe disturbs. Ask whether a concrete cut for a buried line is included or left to you. Ask what happens if the grade at the discharge needs fill, and whether that fill is a line item. Those three answers separate a quote that will hold up in January from one that turns into a surprise.

What to ask

1. Where will each downspout discharge, and how far is it from the foundation and from any walk?
2. What is the length and material of each extension, and does the bottom elbow change?
3. Will each discharge line slope away from the house at a steady drop, with no low point where water can freeze?
4. If the water crosses a walk or driveway, what is the plan to keep it from freezing across that path?
5. Does the price include restoring any lawn, walk, or bed that the work disturbs?
6. Is a downspout strainer included, and will the outlet be cleared at the time of install?
7. Who checks the discharge points after the first hard freeze, and how do I reach that person?

If you want someone to look at the discharge points on your lot before the first freeze, call Keys Roofing at (314) 220-2333. Ask that the full path of each downspout be measured, not just the bottom elbow, so the quote matches where the water actually goes on your property.