Frozen downspout: why it happens and what to leave alone
A downspout that will not drain is a clue about the gutter above it. Read it from the ground and let it thaw.
A frozen downspout is a pipe plugged with ice, so the water in the gutter has nowhere to go. It happens when a thaw sends meltwater down the pipe and the cold night freezes it in place. The pipe itself is rarely the fault.
Why downspouts freeze
A downspout is a thin metal tube that hangs on the outside of the house. It has no heat and almost no insulation. Water that trickles in on a mild afternoon sits in the pipe, then turns solid when the temperature drops. Small amounts of leaf debris at the elbow make it worse, because they hold water in one spot.
The gutter above it often has the same story. If you also see thick ice along the trough, read what ice in gutters means first.
What a frozen downspout is telling you
Check from the ground. Binoculars help.
- Water spilling over the front of the gutter above the downspout means the pipe is blocked, not that the gutter is too small.
- A long icicle hanging from the bottom of the pipe means water has been running and freezing at the outlet.
- A bulge or split seam in the pipe means the ice has already pushed the metal apart.
- A sheet of ice on the ground below means the pipe is leaking where it should not.
None of this proves a roof problem. But if the same downspout freezes every winter, the water feeding it is probably meltwater from heat loss under the roof. That is the pattern behind most ice dams, and our page on what causes ice dams explains it.
What not to do
Do not pour boiling water down the pipe. It can crack the metal or the joints, and it refreezes lower down, which makes the plug longer. Do not hammer the pipe, and do not stab at the ice with a rod. Do not climb up to the gutter to clear it from above. A wet ladder against an icy gutter is a poor place to be.
Salt in the pipe is a bad idea too. It runs onto the soil by the wall and corrodes the metal.
Let it thaw, then deal with the cause
In most cases the right move is to wait. The plug melts on the first mild day and the water drains. Keep people and parked cars away from the base of the pipe, because ice can drop from above.
A heated cable is a patch, not a fix. It keeps one pipe open and does nothing about the warm roof deck above. The lasting answer is a colder roof: sealed attic air leaks, an even blanket of insulation and open soffit vents. The order is laid out in fixing ice dams.
Where our topic stops
We cover the downspout down to the point where the water reaches the ground. Where it goes after that is a drainage question for another page. Make sure the pipe ends clear of the wall and stays open at the outlet.
When to call someone
If the pipe has split or pulled off the wall, call a gutter contractor once the thaw arrives. If the gutter above sags under the ice or the fascia looks bowed, ask a roofer to assess it from a safe position before anyone repairs it.
Frequently asked questions
How do I know if my downspout is frozen?
Water overflows the gutter above it, an icicle hangs from the outlet or nothing comes out during a thaw. Check from the ground.
Is it safe to pour hot water down a frozen downspout?
It is not recommended. Boiling water can crack the pipe and joints, and it often refreezes lower down and makes the plug longer.
Will a frozen downspout damage my roof?
Not by itself. But the water backing up in the gutter can overflow and soak the fascia, and the same heat loss that freezes the pipe can cause ice dams.
Do heated cables fix frozen downspouts?
They can keep one pipe open, but they do not address the warm roof deck that created the meltwater in the first place.
Sources
What this page explains is based on these official sources. If you check one and it does not match what you read here, send it to us and the article gets corrected.
- NOAA / National Weather Service. Winter — National Weather Service safety hub
- NOAA / National Weather Service. What To Do If You're Caught in a Winter Storm