Upstairs bathroom exhaust fans creating icicles in attic

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Posted by: from Cochrane
12/27/2017 at 12:14:31 PM

Hi everybody! New here and i have a problem!

I living in Alberta, and I have a two story house built in 2007. I found a wet spot on the ceiling in my upstairs bathroom. I climbed up into the attic and I found a bunch of icicles and frost growing around the flashing of the vent termination. The insulated fan hose exhausts through a roof vent.

I got closer to it and noticed the following problems:

1) The flashing on the vent appears to be misshaped, and not sealing flush against the roof sheathing, allowing the fan exaust to pass into the attic.

2) There also appears to be some wood rot on the OSB where the vent is located, so this looks as if this problem has been going on for some time.

3) Above my other upstairs bathroom is a bunch of frost, although there are no icicles.

The pics I have attached show the vent fan after I broke off a bunch of the icicles.

My question(s) is:

1) What is the best way to seal the leak? Can I silicone/tar under the flashing?

2) Should I be concerned about the wood rot that has occured?

Any advice would be greatly appreciated!!

Also, the vent tubing was just duct taped on by the builder.



Upstairs bathroom exhaust fans creating icicles in attic
Upstairs bathroom exhaust fans creating icicles in attic
Upstairs bathroom exhaust fans creating icicles in attic
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Jarrod from JTB Electric Ltd. in Camrose
Date/Time12/27/2017 at 1:05:20 PM

Contact a HVAC contractor & roofer for proper advice on the venting/roof vent.

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Robert from ElecTriLight Ltd. in Oakville
Date/Time12/27/2017 at 1:38:03 PM

unfortunately, this is a common idiot practice of lazy builders and inspectors. They are too cheap to install the proper roof flange and connect it properly. There are ways to ensure this is 100% correct using insulated duct right to the roof and a proper roof flange with a 4-6" duct port on it. The duct should not run vertically as this will allow all moisture not evacuated to simply run back into the pipe and fan enclosure. It should run horizontally and be vented out the wall, soffit or a slight incline. Flexible duct with ridges inside should be avoided to prevent water from being trapped inside, use rigid pipe. Install a timer on the fan as well up to 2 hours and run it for an hour a day to dry the duct after the moisture has been drawn through.

Winter is the worst time for this as the cold air and hot moist air meet where ever the exit is and will cause ice buildup. Out east, we only use wall or soffit vents as roof vents freeze and get covered with snow blocking passage of air completely. It is a bad design for snowy regions.

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Date/Time1/2/2018 at 5:11:36 PM

Hi Joe

YIKES! this is the best to post on how not to build a house and get away with it!!!!

enough said, this has to be fixed ( not now )Too cold. This will need to be cleaned up and new insulated and sealed rigid tube as required by building code in most regions. A good temporary fix is to get a small can of spray foam and slowly encircle the area of leakage, do this on a calm day wind free this will allow better adhesion.

When it is time in spring this can easily be cleaned off and the repairs can be made. Please

Find yourself a quality contractor by checking this site and or your local Home building supply or if there is an HVAC supplier close to you as them for a reference. We are in Ontario and if we did the repair it would probably be completed in a few hours.

Best of Luck Tony Soda

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