Downspout Clogs: The Causes and Solutions

Gutters collect rainwater that runs down the roof and directs it to the downpipes, expelling it from the gutter system a safe distance from a house. When downspouts work properly, they prevent increased moisture levels in the soil, damage to the foundation, and basement flooding. Downspout clogs can cause significant problems, including overflowing gutters, mold on interior and exterior walls, and pooling water. Here are some common causes and solutions for downspout clogs.

How Clogs Form

Clogged downspouts are caused by the same process that causes blockages in gutters. As leaves, twigs, asphalt shingle granules, pine cones, seed pods, and needles flow through the gutter channels, bits of organic materials can collect around the gutter outlet or become snagged on places inside the downspout. Since they are virtually out of sight, blockages inside the downspouts typically buildup gradually. But eventually clogs grow large enough to impede the flow of water exiting the gutter system.

Signs Downspouts are Clogged

While you might not be able to see the actual blockages inside the downpipes, there are some visible signs downspouts have become clogged. These signs include:

  • Overflowing gutters – spilling over the sides at the front or sliding down in between the back of the gutter and the fascia
  • Joints or seams leak – clogs in the downspouts cause standing water in the gutter channel that puts added stress on seams or joints; clogs inside the downspouts can also apply pressure to the seams that join sections of the downpipe together
  • Water trickles from the bottom downspout elbow – water leaving the gutter system should flow freely

Solutions for Clogged Downspouts

Keep the roof free of debris.

Clean the gutters and downspouts regularly. Make sure the gutter cleaning schedule you choose fits your property’s profile – the recommended twice a year might not be adequate if you have lots of trees on your property or in the neighbourhood, live an agricultural community, or live by a busy highway.

The most obvious sign that downpipes are blocked from the inside is there is no water or just a weak trickle coming out of the downspouts. See below for instructions on how to clear a clogged downspout.

When the gutter constantly overflows near the downspout, check the gutter outlet – where the gutter channel connects with the downspout. Look for any buildup of debris and clear it away from the outlet.

When sections of the gutter system constantly overflow, the cause is most likely a blockage or blockages inside the downpipes. The clogs will have to be removed.

How to Remove Clogs from Downspouts

Typical places debris can builds up in a downspout at the top, in the middle, and above or below the bottom elbow. To remove clogs and blockages for inside downspouts, follow these simple steps:

  1. If the gutter outlet is free of debris and the blockage is visible at the top of the downspout, try removing the gutter outlet before attempting to take the clog out.
  2. If the gutter outlet is free of debris but you can’t see any clogs at the top of the downspout, the blockage is inside the pipe.
  3. To ascertain where the clog is lightly tap down the length of the downspout. When you here a “thud” as opposed to a “clang” the blockage is probably in that part of the pipe.
  4. First try flushing the clog out with a garden hose inserted into the downspout at the top. If that doesn’t work, try removing the clog with a plumbing snake.
  5. When blockages are located just below or above the elbow, try prying it loose with a length of wire or a plumbing snake.
  6. For really stubborn clogs situated in the middle of downpipes, you might have to remove that section (where you heard the thud) of the downspout from the wall to get rid of the blockage.
  7. To make sure that the downspout is totally unclogged, flush water through the downpipe.