Foothills Roofing Calgary
  • Home
  • About Us
  • Why I do what I do
  • Services
  • Gallery
  • FAQ
  • Random Thoughts from an Old Roofer
  • Contact
  • Snow Removal

Why does my bathroom ceiling fan drip?

5/2/2018

30 Comments

 
​ At this time of year with the onset of cold weather and fluctuating temperatures,  homes in the Calgary area can experience problems with bathroom fans that leak water or develop stains on the ceiling around the vent. 
Properly installed and used a bathroom fan should not leak in the summer or in the winter.  If the vent does not leak in the summer,  especially during the heavy rain that often accompanies  thunderstorms, it indicates that the shingles and flashings were installed correctly and shedding water off the roof as intended. Water that drips from the fan during cold winter weather is usually an indication of a problem with the venting system not the roof itself.
​During cold weather  some moisture will always condense on the inside of the vent pipe, where it passes through the cold attic.
To operate properly a bathroom fan venting system needs to move sufficient air up an insulated pipe and outside of the house to remove excessive moisture from the home.  This requires a fan that is rated to move enough cubic feet of air for the size of the room being vented, a vent pipe large enough that this air flow is not restrict and a vent in the roof to allow air out of the home and keep water from leaking in.
Picture
Picture

The Fan
Bathroom fans are rated in two ways; by the amount of air they move and by the amount of noise they make. Generally speaking the less expensive the fan the less air it will move and it will make more noise while doing it. Fans are rated from 50 cfm ( cubic feet per minute ) up to 180 cfm or more. The noise that they make is measured in Sones and usually range from .03 up to 4 for less expensive models . A sone is a measurement of sound in terms of the comfortable hearing level for the average listener. One Sone is the equivalent to the sound of being in a quiet kitchen listening to a quiet refrigerator running.

The Vent Pipe
Venting the fans has been done in a variety of ways in the past; metal pipe, plastic pipe, insulated and uninsulated often using the shortest route possible. For many years we dreaded the Chinook winds and the quick rise in temperatures that it brought, we would be flooded with calls from new home owners that had dripping fans. What we eventually found worked was using the proper size insulated plastic pipe for the fan flange  and run the pipe horizontally on the ceiling wall board under the insulation for about two feet. Working with the HVAC companies and getting them to  run the vent pipe across the ceiling was all we needed to do to eliminate most of these calls.   The pipe can then run up to the roof vent with as few sharp corners as possible. This allows small amounts of moisture that condenses on the inside of the pipe to collect on the horizontal run without dripping into the bathroom. When the fan  runs this moisture is  drawn out with the air without causing any problems.  
 

 
The Roof Vent
The vents that are used on the roof to vent fans are known as goose necks.  They rise up from the roof deck about six or seven inches curving down toward the roof to vent the air down toward the roof deck, looking somewhat like a gooses head.  They are larger than the pipe that they vent so that the air flow is not restricted. The opening is covered by a screen or metal damper to keep critters out and allow maximum air flow.


​




Operation  of the fan
The fan should be run for fifteen or twenty minutes after the shower or bath is used. During very cold weather it is a good idea to run all of the fans in the home, even if the bathroom is rarely used, every couple of days for same length of time to remove the moisture that will naturally condense on the inside of the vent pipe from the slow trickle of air up the pipe. Running the fans will prevent excessive frost build up and the drips that can result.
Properly installed and used bathroom vents should give many years of problem free use and make the bathroom more comfortable. 



30 Comments
evelyn
12/4/2019 04:13:38 pm

i would like a quote to vent my bathroom fan through the roof.
please contact me @ 587-429-3020

Reply
Rebecca link
21/4/2019 10:34:46 pm

What's the best way to get a quote?

Reply
Mike
23/5/2019 10:04:36 am

Hi Rebecca, the best way is to phone us at403-669-6095 or email us at info@foothillsroofing.ca at we arrange a time to meet and look at the job with you

Reply
Karla link
29/5/2019 03:46:32 am

This is the reason why I let professional do the installation so it will not create any trouble in the future. It is really hard to fix problems, especially around your ceiling area.

Reply
Ann
11/1/2022 05:59:24 pm

I did and I have a worse problem

Reply
JP Zonneveld
14/2/2021 02:34:04 pm

Our fan does drip but solely during cold snaps. I investigated the attic and everything looks good. No sign of a leak anywhere. The dust remains dry and mobile and there are no stains on the underside of the roof or anywhere else. I assume therefore that our fan is insufficient for the volume of air it needs to move. I'll buy and install a more powerful fan, but I would appreciate your recommendations for a more powerful, yet quiet, fan.

Reply
Mike link
16/2/2021 01:10:44 pm

Hi JP,
We have found a few things over the years that can cause bathroom fan to drip water in the winter. The insulated vent pipe should run horizontally under the insulation for about two feet before rising to the roof vent. This allows a small amount of water to collect in the pipe before it is vented outside with the air flowing through the pipe.
A few years ago it was common for the pipe to vent pipe to just go straight up to the roof vent. When done this way even the smallest build up of frost will leak water into the home.
The roof vent should also be check to insure there is no blockage there.
Assuming all is good, I like Broan's Bathroom Fan - Invent Series rated to move 110 CFM. One of the good things about these vents is they can be installed without having to going to the attic.
Which ever vent is used it should be moving a minimum of 100 CFM

Reply
Roof Hatches link
15/7/2021 05:40:05 am

The way you discussed the topic with ease and completeness is really amazing. Thanks for this article!


Reply
Roof Doors & Hatches link
15/7/2021 05:45:45 am

The way you discussed the topic with ease and completeness is really amazing. Thanks for this article!


Reply
Rick Cudmore
11/12/2021 12:11:51 pm

We live in a townhouse condo and the main floor bathroom exhaust fan started dripping water during the cold weather of Dec. There are no stains around the fan casing. The bathroom is 10' x 8' and 8' high. A contractor replaced the roof vent stating it was not installed properly and this was the cause of the leak. Three days later the bathroom vent began dripping. Another contractor arrived and caulked 'everything', their words. Next day the fan dripped again. It appears the drip occurs when it has snowed more than when it has rained. The duct is insulated and the condo is 20 years old. We run the fan 10 minutes after each bath/shower. Your suggestions or comment would be appreciated as the management company is not sure how to proceed.

Reply
Mike
13/12/2021 07:55:57 am

Hi Rick,
You didn't mention if you have just moved into this home or if you have been living there for a while and this problem just started.
I have a couple of suggestions for you that may help.
The fan should be left running for 20 to 30 minutes after a shower a little less when it is a bath. This will give the fan time to take all the moisture out of the room and the vent pipe. If the fan is not run long enough moisture can freeze inside the vent pipe. Then when it warms, either from a chinook or sometimes when the fan is turned on again, the frost melts and will leak out of the ceiling fan.
If running the fan longer does not solve the problem it is most likely the vent pipe from the fan to the roof vent that is the problem. Twenty years ago it was common for the vent pipe to exit the fan and go start up to the roof vent. Many of these pipes were poorly insulated also. Working with HVAC contractors we found that running the vent pipe horizontally across the ceiling under the insulation and then having it rise to the roof vent fix most of the bathroom fan leaks we were having in newly constructed homes. This give the small amount of water a place to sit before being exhausted from the roof vent. With out this horizontal section of pipe even the smallest amount of water in the pipe will come out of the ceiling fan.
If these ideas don't help we would be happy to complete an on site assessment of the problem.

Reply
Eman
9/1/2022 11:31:31 pm

Thank you, your explanation is really helpful. Wish you very happy new year :)

Reply
Zafar
12/1/2022 09:32:02 am

My home is less than one year old and have water dripping problem from the ceiling fan in the bathroom. I’ve a couple of questions; will my New Home Warranty cover the expense and secondly, who to call for help i.e Roofing company or Insulation guys or HVAC guys. I’ll appreciate a quick response

Reply
Mike
13/1/2022 08:39:10 am

Good morning Zafar,
This is not something that the New Home Warranty would cover, it usually needs to be a structural issue for them.
If the home is less then one year old the home builder should have a warranty against small problems like this. I would recommend contacting the home builder and see if they will investigate the problem.
If they won't or can't help we would be happy to have a technician look into the problem for you.

Reply
Zafar
13/1/2022 11:20:55 am

Thank u very much for the prompt reply. Yes, I’d like to have a technician look at it. (I’ve left a message in your voicemail as well. My contact number is (403) 473 8046)

Roofing Contractor link
17/6/2022 06:34:29 am

The article is awesome. Having your fan ventilation installed properly will give you peace of mind that it won't damage your roof on the long run.

Reply
Christine
12/1/2023 09:19:55 pm

Our house was built 30 years ago and I’ve owned it 11 years. The primary bathroom has never had a dripping fan issue until just recently. I noticed a couple water marks near the fan in December - after the really cold snap in Calgary. I assumed it was due to the -40C weather. However, just today, the fan was dripping and it’s been fairly warm for winter here (-10C this morning and 2C during the day). Now, I did use the shower this morning and didn’t run the fan for long after. But, it seems odd that after 30 years this fan is just now dripping. I will add our roof was replaced last February as a result of hail damage. Not sure that’s a trigger, but this is the 3rd roof since I’ve owned; could be just a coincidence.
Any suggestions?

Reply
Mike
13/1/2023 11:29:43 am

Hi Christine,
Since you were not having problems until this winter and have been in the home many years now I would suspect that the problem could be due to the roof replacement that was completed last winter.
Something that we see occasionally is the roof vent covered by the underlay or shingles. You can check to see if the fan is drawing air by holding a tissue up to it, the tissue should stay there until the fan is turned off.
I would have the roofing contractor come back to see if there is a problem with the installation.

Mike

Reply
superpowerelectricnj link
2/3/2023 08:09:21 am

Ceiling fans are not just something people use in the summer; they’re also used a lot during the winter especially if you purchase one with a reversible motor.

Reply
Kitt
2/3/2023 03:09:25 pm

Hi! Our exhaust fan is dripping after strong winds. The roofs are full of snow during this chinook wind. Is it possible that this strong winds blew a lot of snow in this vents to cause exhaust fans from dripping? Its very windy where I live and I thought this strong winds blew a lot of snow in our goose head. :) not sure what direction the wind is blowing. Thanks for the answer in advance.

Reply
Mike
9/4/2023 08:50:30 am

Hi KItt,
Yes it is possible for snow to blow into the roof vent with strong winds and it can cause the fan to drip as the snow melts.
Often changing the roof vent to a style that has a damper instead of a screen will solve the problem.

Reply
Kitt
30/8/2023 04:19:16 pm

It rained enough to know that there is no leak. I cleaned the stain first to make sure there is no leak when it rained so it easier to know. Its just the strong blowing snow that really get in the vent. Thanks

Roofing Portland CT link
7/4/2023 01:22:44 am

It’s a great source of knowledge; I think it will be helpful for a lot of people who are looking for learning more about why my bathroom ceiling fan drip. Thank you very much for sharing this article.

Reply
Tom
8/4/2023 06:32:44 am

You mentioned insulated plastic pipe to use on bathroom vents, exactly what name brand and where to but it?
Thanks Tom

Reply
Mike
9/4/2023 08:45:35 am

Hi Tom,
This is the 4" pipe we use, it is from The Home Depot.

Dundas Jafine Flexible Insulated Duct, Residential 4 inchX10 foot
Model # XPC410|SKU # 1000449710

Reply
Tom
10/4/2023 02:16:46 pm

Thanks for responding, I have to redu my bathroom vents, they’re routed to the soffit. Another issue I’m having is I get condensation build up in my flex pipes for the ac handler in the attic. Had a couple contractors look at it, one had no response but another said my trunk to handler was way to small, so I had that fixed and two vent runs that had water in the flex hose. I’m thinking I’m getting most of my condensation during the winter when the heat is on in the house. I usually cover my ceiling registers with press and seal. The two that got water in it, I didn’t cover because they were brand new and thought it would be fine but it wasn’t. Water eventually was coming through the register. Not sure if my handler changes will help next winter. Have you experienced this?

Reply
Naveen link
14/6/2023 07:04:39 am

Thanks for the sharing informative article.

Reply
Francesco Longo
6/8/2023 05:48:23 pm

i hve water leaking near the toilet fan when gets very cold

Reply
Mike
7/8/2023 06:33:28 am

Hi Francesco, it sound like there may be a problem with the insulated vent pipe or insulation in the attic. We would be happy to look at it for you and recommend a solution. Please call the office at 403-669-6095

Reply
Dustin
30/8/2023 01:09:43 pm

Hello, thank you for this article. After installing new fans and ducts last summer, we had the same issue with condensation freezing in our ducts and dripping in the bathroom. Is there an HVAC company you’ve worked with for addressing this, or one or two you could recommend?

Reply



Leave a Reply.

Home

Services

FAQ

About

Contact

©2018 Foothills Roofing Ltd. All rights reserved.
  • Home
  • About Us
  • Why I do what I do
  • Services
  • Gallery
  • FAQ
  • Random Thoughts from an Old Roofer
  • Contact
  • Snow Removal