# roof drain downspout ice melt question



## jamesdorven (Sep 8, 2011)

I have a flat roof and two roof drains that exit the back lot of the building about 10 feet in the air with 2.5"(i think) PEX plumbing pipe. I have 8 Watt/foot heat cable inside of each drain in a loop (so "double" the cable inside the pipe). the pipes open end is about 3 feet off of the ground. the water drips out and freezes on the driveway, forming an enormous icicle which grows all the way up to the pipe and freezes the inside of the pipe as well. the heat cable simply cannot keep up with the ice, and the junction of where the pvc meets the metal drain inside the ceiling will end up blocked, and water will overflow out the plastic trap door (PEX plumbing) in the ceiling. how to avoid this?

1) Code doesn't allow for the water to stay inside the house and drain into the sewer system
2) I don't know if 1" foam pipe insulation will help much, since the pipe is open on the bottom anyway. Maybe a $300 gamble
3) A hydronic radiant heating system with usage PEX tubing from Oxypex
4) More powerful heat cables such as easyheat SR81 would be at least another $1,000 including labor, and don't know if it would make a difference
5) Sealing the junction of the PEX and metal drain pipe inside the ceiling would cause the water to sit on the roof, and then if that froze, it would rupture the seam between the drain and the rubber roof and be catastrophic. at least water coming out of the ceiling into a bucket is a relief valve of sorts
6) Knocking the icicle away and banging on the pipe with a hammer is the low-tech solution, but the icicles don't take long to grow back


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## 1985gt (Dec 21, 2010)

Does the heat tape extend out past the end of the drain pipe or is it stoped short inside? If its extended out of the pipe there should always be a path for the water to escape even when it freezes. other then that Ice melt of the pavement?


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## shazapple (Dec 3, 2010)

Why is there water on the roof in the first place when it is frozen everywhere else? Perhaps you have an insulation problem. 
Is the driveway asphalt? can you dig out the area underneath the pipe and put in some crushed rock and whatnot for drainage?


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## TFaulkner (Apr 26, 2011)

@ shazapple - No matter how much insulation they have there will always be some heat that escapes and melts the snow on top of the roof. 

James - Have you thought about adding another pipe to the one that's freezing to divert the water somewhere else? Could at least get it off your driveway.


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## Warmsmeallup (Jan 30, 2009)

1985gt has it right, partly. The cable should extend right to the very drip edge, but not beyond. You want the water to drip off but not be able to build back up. Also, be sure NOT to bend the loop into a crease. It must have at least a 1" radius at the end. If you extend it beyond the drip edge, you take the chance of critters chewing on it.

Next, increase the cable to 12 watt plf self-regulating cable in a loop. We won't install a system unless we can use 12 watt loops. Otherwise it will 'igloo' around the cables.We found that using single temp cables just don't make it happen above the DC line in the northeast.


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## Pie in the Sky (Dec 21, 2011)

12 watt self-regulating is the way to go.
I’d bet these lambs tongues are on the north side of the building, sun melts the roof snow, temperature freezes it on the end of the lambs tongue.  
Properly designed the water would have remained in the house and taken out below frost line and dumped in a public storm water system or a dry well under ground. At this stage its well over that 1k$ to do that. 

I guess I always just hated how you have to chase the ice with the heat tape. I get called in, they heat tape and then they have a pile of ice, then they put ice melt there and it runs a little further and freezes.. It’s a vicious cycle. 
I was on a roof the other day in Snowmass which was designed as a flat roof. they said it held too much snow, (even though it was designed to) then they over framed and put a metal roof on it so the snow would slide off. Well all the snow was falling off the roof and hitting people and cars. So they put snow fences on the whole thing... so we’ve come full circle of wanting it on, wanting it off, back to wanting it on. and it’s going to come off anyway and probably be worse when it does. 

I guess it’s all just a lesson in proper design, if it’s cold in your area, plan for management of snow and Ice!!!


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## Warmsmeallup (Jan 30, 2009)

*There's always under metal heat!*

There's always Under Metal Heating...low voltage!


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## warm stuff (Sep 24, 2015)

1985gt said:


> Does the heat tape extend out past the end of the drain pipe or is it stoped short inside? If its extended out of the pipe there should always be a path for the water to escape even when it freezes. other then that Ice melt of the pavement?


This is key. Also, you may look into a different cable. Self Regulating tends to be the best, and you will want a higher wattage than the cheap stuff at the hardware store.


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## johnmeto (Aug 30, 2015)

Does the warmth tape reach out past the channel's end pipe or is it stoped short inside? In the event that its stretched out of the channel there ought to dependably be a way for the water to escape notwithstanding when it solidifies. other then that Ice melt of the asphalt?


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