Roof Vent Ice

By
©1993-2012 Tim Carter

        
Summary: A roof vent cap can keep debris out of the vent, but it can also ice up in the winter. This ice can block the roof vents. Can the cap be removed?
DEAR TIM: My vent pipe running thru the roof extends about 30 inches above the roof and has a metal cap on it to keep debris out. Ice formed at the end of the vent pipe and blocked it.  Do I need this cap on the vent, it seems to create ice and block it, Can I leave the vent pipe open with no debris cap on it? Cleon Shafer, Coram, Montana

DEAR CLEON: I can see why the ice forms, as you sure get cold temperatures there. The water vapor rising from the plumbing system readily condenses, and then flash freezes on the cap. As this happens continuously in bitter-cold weather, it's no wonder the plumbing vent clogs with ice. When this happens, the plumbing system will get starved for air.

The bottom line is that you can remove the cap. I can't imagine why you would need it in the winter. Not seeing your house, I would think it may have been put on to stop debris from overhanging trees. But if those are deciduous, they have dropped their leaves by now.

Once there is no snow or ice on the roof, I would periodically check the vent pipe to ensure it is free of any organic debris. If the vent system is connected correctly to the drain pipes, you can insert a garden hose into the vent pipe to flush debris into your sewer or septic system.



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Welcome! I, Tim Carter, don't answer questions here. If you post a question here in the Comments Area, perhaps another visitor will help you. You need to go to the Ask Tim page if you want a question answered. Once there, look closely at how many weeks behind we are. Please be patient as you use this free service. If you have an emergency and need to talk to me, there is an option there for you.
Charlie Chipmunk
23 Dec 2008, 20:12
The cap isn't just for debris, it is to keep animals out as well. This is especially true in the cold winter months during which animals want to find warm spaces, such as one might find by crawling through your vent stack.

If you have access to remove the cap in the winter you have access to knock the ice off. Do that and use the winter months to locate a different cap that won't cause the same problems but will keep the animals outside.
Scott Cole
05 Mar 2009, 16:19
I have the same problem with the vent cap for the bathroom fan vent. Ice forming and dripping into the bathroom. Heavy snow here. Is there a better vent/cap. Ours is brown plastic and flat.
majdi
31 Mar 2009, 12:20
to protect your vent from ice or any falling objects , easily you can make bend by using 2 nos. of elbow 90 degree. to reverse the vent cap direction from up to down .
fulfer
05 May 2009, 09:31
gas heaters have vent pipes too???

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