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Question DetailsAsked on 2/10/2014

How do I thaw a frozen downspout?

I've got a frozen downspout on the corner of my house due to multiple high snowfalls this year & crazy low temps from polar vortexes (Indiana). Should I try to thaw out the downspout? Looks like the freezing is backing up to the gutter, making me concerned the ice build-up could overload the gutter with weight and cause it to pull away from the roof. Any suggestions?

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4 Answers

Voted Best Answer

The ice build-up in the gutter should not, provided they are properly attached and solid, rip out the gutter.

When you get snow slides and large chunks of frozen precip that let go and slide down the roof with velocity, those are what tear off the gutters and create damage.

If you are concerned about the snow load, a snow rake and/or a proper roofer can remove some of the accumulated snow.

Some ice damming is unavoidable in the correct conditions but I would urge you to look into proper ventilation of the roof and air sealing and insulation. This will reduce your home's inclination to form these ice dams in the future.


Answered 5 years ago by WoWHomeSolutions


Wrap it with heat cable.

Answered 5 years ago by Davidhughes


Actually, with the light weight metal gutters being sold these days and the wide spacing used for brackets (2 feet typically), it is not uncommon to see damage from ice buildup and glaciering of gutters, and downspouts ripping off walls because they used the recommended bracket spacing instead of 18" or so.

A number of ways to do it, pick the one that works for you - in each case, be sure water runoff is not ending up right by your foundation or otherwise causing damage like glaciering your walk or drive, and beaware with ladder work that steps willget wet while you work, so expect them to be icy.

1) pour hot water (full hot from the tap) in the gutter - and to get the downspout started if frozen solid at any point, fill top with hot water to full, then pour hot water on one side of outside of downspout to melt a small channel inside the pipe for the water from the top to start running down - usually will only take 1-2 gallons of hot water dribbled down the outside to thaw enough interior channel to start flow, then you can add hot water from top to melt out the rest.

2) wrap with heat tape, as prior suggestion said. Has to be low-temperature tape (not over about 120F) if on plastic downspout, to avoid melting it.

3) put hose on a faucet and run hot (but not full hot, to avoid melting hose) water and run water on outside of downspout to heat one edge, then run hose down into downspout with hot water to melt your way down, and from ladder put hot water into gutter starting at the downspout and working back toward high point while thawing enough to avoid blockage overflow, so it does not overflow on you and soak you and cause icing on the ladder. Then run water at high point of gutter till rest of ice frees up - takes FOREVER to totally melt with water, much faster to get it started enough to loosen up the ice in the gutter, then pull out lengths of ice by hand and throw them away. You will need heavy rubber gloves for this - I use this type with a fabric lining for warmth -

Pull hose back periodically to enlarge hole while in downspout so you do not get it stuck in the ice, as it will try to freeze in on you above the point where the nozzle is. If you are not into getting up on a ladder, you can buy a length to three (depending on gutter height) of 3/4 inch PVC pipe, three 90's, and a hose thread female fitting plus glue (or threaded PVC and fittings to allow disassembly for storage till next year), and make up an upside down J shape with the pipe that will put the water into the gutter, with the hose fitting on the bottom - only weighs about 5-10 pounds empty so easy to handle, and once hooked in gutter you can slide sideways without lifting entirely up. Disadvantage is you can't see how thawing is going, and of course if gutter overflows you have to move fast or get drenched with debris and icy water. BTW - 1/2" pipe willwork for about 10' (one length) - too flexible for greater height, get 3/4" for more height or if you anticipate using this to also clean out french drain or yard drain pipes or iced culvert under drive - all of which of course mean the J part at least has to be threaded for removal. Total cost under $50 including jet nozzle.

4) stick hose with jet nozzle like this (first two shown)

up into bottom of downspout, and shove up as it thaws from the bottom up - you need long rubber gloves for this or you will freeze your hands.

5) Use heat gun or blow dryer on a heat that is not too hot to touch (so you don't blister paint or melt plastic downspout) and heat downspout from bottom toward top till top blockage drains, then work around until ice inside breaks free and drops - very slow going if outside temp is low as pipe radiates heat away about as fast as you heat it. Do NOT stick in bottom of downspout to thaw - when ice or water breaks free and comes down you could be electrocuted.

6) Not great for plants below and promotes rust in steel and corrosion in aluminum downspouts, but you can dump about 2 soupcans full o of ice melt in top of downspout and on ice in gutter right next to it and let it melt its way down over the course of a day or two, then rinse salt away after thawed out. Slower than hot water, and not as good for the gutter or plant materials, but works. Ditto to ice in the gutter, though you will need several pounds for an entire gutter, and can kill grass in runout zone at that dosage.

Answered 5 years ago by LCD


BTW - do not think you can hurry the process along by putting a thaw cable direct in the gutter - they are not really made for direct immersion in water, and that is just asking for trouble. Wrapping around the downspout will take a bit longer, but so what.

Answered 5 years ago by LCD


Buy a heat gun and starting at the bottom of the downspout apply high heat all around to melt a small area just inside the spout. The downspout is rigged, not flat, so as the thin layer inside melts AND the downspout expands a little from the heat a small channel will form allowing the melted water to drip down.

Once you have it started by hand (you only need to do a couple inches), rest the heat gun on a pail or stool or something aiming at the long side of the pipe and leave it. The small channel inside will get bigger and bigger as the warm air inside rises and melts its way up. Mine freeze all the time, it takes a couple hours but once started you don't have to tend to it. Of course use common sense and make sure the heat gun is sucurely in place and cannot shift and heat anything else.

If you want, ONLY AFTER you have a channel all the ay to the top should you consider pouring hot water. The hot water needs to have passage through and might melt some ice along the way. Adding water while the spout is still blocked will only end up adding more ice. In that situation water will go from boiling to ice just a couple minutes (think if a Zamboni on an ice rink - pours hot water on ice and it melts a small bit at teh surface but quickly freezes back over).

Mine empty into drainage pipes so I can't do this, but if yours just end and dump the water you can remove the elbow at the bottom, and if you want to move the heat around a section at a time, as the ice toucing the inside wall melts it is essentially "hanging" their inside the pipe. Tap the pipe gently (looking more for vibration than banging) and the thawed setion will break loose and slide down through the bottom. Take a hammer and break it up as it comes out and do another section. Once you get teh first section to fall it goes pretty fast.

I will tell you the heat gun could leave a little burn mark on the pipe. I just deal with it and in the spring take 5 minutes and paint over it.

For my gutters I bought these de-icing cables. they lay inside the gutter and then zig-zag up/down the roof line about a foot and prevent freezing. THEY WORK GREAT! (got mine at Lowes) This however is what lead to my downsput freezing problem lol Never had frozen downspouts until I installed the de-icing cables. (Again an eexample of how fast water freezes - from the gutter where the cables are it turns to ice before it can fall down the spout!) Catch-22 though. If I didn't have the de-icing cables I'd have frozen gutters and ice damming (maybe). I live in CT so when it would snow the gutters fill up with snow, hours later it's 45 degrees and it melts - but not all, the snow becomes slush then hours later it's 12 degrees and your gutters are frozen!

This winter I'm going to try snaking one of the de-icing cables all the way down the downspout.

Hope this helps.

Answered 4 years ago by CTHomeOwner

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