Preventing frozen downspouts

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Old 01-14-19, 12:17 PM
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Preventing frozen downspouts

I have a problem with downspouts freezing under certain conditions. Usually, it's when temperatures are right at or just below freezing, but the sun is enough to get some melting going on the roof. The downspouts are out of the sun, so they stay below freezing. The water freezes as it goes down, forming a giant icicle at the bottom that eventually blocks the downspout and then causes the whole thing to back up and freeze. It only seems to be an issue with my longer downspouts. The 1-story spouts don't freeze solid, but the 2-story ones will.

I'm currently using gutter/ice dam heat tape in the bottom of the downspouts to keep them flowing, and it works well. But is there a better or more effective idea? The house wasn't set up for the heat tape as a permanent installation, so it's a bit of a PITA to go run extension cords all over every time it's going to snow.
 
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Old 01-14-19, 12:23 PM
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I think it's standard practice for owners who run heat tape along the lower edges of the roof to extend a length down thru the downspouts. Water is going to refreeze sooner rather than later depending on the temps outside.
 
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Old 01-14-19, 04:31 PM
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forming a giant icicle at the bottom that eventually blocks the downspout
So it sounds like the downspout needs to drain away from the downspout.

Water flowing down the downspout really doesn't have time to freeze as long as it flowing and not standing!
 
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Old 01-14-19, 06:39 PM
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Downspout drainage doesn't seem to matter. The downspout that goes into a downspout extender freezes solid where it connects. I took a section off of another downspout and let it terminate a few feet above ground. I got a giant icicle that reached from the downspout to the ground. I even have one that goes into a buried pipe. The downspout froze solid. I disassembled the downspout, and removed the frozen section. It had an icicle a couple inches long at the bottom, but the pipe was totally clear.

When I check on the downspouts before they freeze solid, I can even feel ice forming along the sides of the downspout. Trust me, ice is building up on the inside of the downspout as the water runs down.
 
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Old 01-14-19, 07:22 PM
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Apparently Marq has never seen a frozen waterfall!

I would second what Viriliter_Agite said about adding a length of heat cable down the downspouts. For those who have them, they commonly zig zag back and forth along the eves, along the gutters, and down the downspouts.

If you currently have 2x3's, the 3x4 downspouts might have a better chance of staying open due to their larger size.
 
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Old 01-15-19, 05:12 AM
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Yes, I started using heat cables in the downspouts. I don't have them along the eaves. I always considered that an ice dam prevention, and I've never had issues with ice damming (knock on wood). The bigger downspouts is a good idea. I wanted to make sure I wasn't missing a simple solution or doing something wrong.
 
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Old 01-15-19, 05:59 AM
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I think you are doing it right SS.
 
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Old 01-17-19, 05:35 PM
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Good to know, thanks. I was wondering if I was doing something wrong, since I'm the only person in my neighborhood using heat tape. Then I noticed the icicles hanging out of downspouts and gutters on my neighbors' houses. I guess I'm just the only one doing something about it.
 
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Old 01-17-19, 08:10 PM
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While heat tape will work in a pinch, you will want to look for deicing cables. They are made for this specific purpose, and come in various lengths. The best kind will say they are "self regulating", which means they only call for power when needed... not like a heat tape that is either on all the time or off. The kind you find at a box store will not usually be self regulating.
 
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Old 01-18-19, 06:15 AM
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Sorry, yes, I did mean deicing cable, not pipe heat tape. Self-regulating, and ordered from a specialty company in the frozen north. And cost about 5x as much as the stuff in the big box.
 
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