Is Your Bathroom Exhaust Fan Leaking When It Rains? (What To Do)

Is your bathroom exhaust fan leaking when it rains outside? 

You are in the right place.

In this special guide from Home Inspector Secrets, we will be going over the cause of a bathroom exhaust fan dripping water and what to do about it. You will learn...

  • why a bathroom fan leaks when it is raining
  • how to fix a bathroom fan that drips water
  • why you should inspect for mold issues
  • how to check out your attic to see what's going on
  • the most common bath vent cover issues that allow in water drips
bathroom exhaust fan leaking when it rains

Why Is The Bathroom Exhaust Fan Leaking When It Rains?

The most common reason a bathroom exhaust fan leaks when it rains is because the bath vent hose is in a vertical slope and exhausts on top of the roof. 

It's a good thing (and required by code) that it's venting to the outside, but the downside is that if it isn't installed properly or if the cover is defective, rain can leak through the bathroom vent.

Also, when cleaning a bathroom vent, a roof exit is the most difficult to deal with.

The phrase "out of sight, out of mind" comes into the picture. Since the ceiling bathroom exhaust fan terminates on top of the roof, it can be very difficult to keep a close eye on it.

Sometimes when we do a DIY job, such as fixing a leaking bathroom fan, we spend a lot of time and money — and then end up hiring a pro to fix our mistakes. That's why I created my Contractor Search Tool, so my readers can get free quotes from local roofers who are licensed and pre-vetted.

I invite you to at least see the pricing from a few trusted roofers—there is no obligation—and then you can decide whether to go ahead with a DIY job. Get your free quotes with my contractor search tool right here.

Read Also: How To Oil A Bathroom Exhaust Fan?

You may be tempted to just vent your bathroom vent into the interior, but this is an even worse idea.

The moisture spewed into your attic of wall cavity may lead to mold growth, wood damage, and may attract termites. 

A Defective Roof Vent Cover

If the bathroom fan is dripping water when it rains, it means that the flashing or some part of the vent cover is allowing in water. It also may be that the damper (flap) is loose or missing --- and is allowing in water. 

In short, you will have to get someone onto the roof to fix it.

Builder's Best Roof Vent Cap

When it rains, water is getting through the cover, and the water is traveling down the vent hose, and then it is exiting from your bathroom fan onto the floor.

Besides the roof, it is also possible (though unlikely) that your bathroom fan vent goes to the exterior vertical wall, and it may have just enough slope that water is still dripping through vent hose and into your bathroom.

I really like the Builder's Best Roof Vent Cap because it is powder-coated and the steel is galvanized. This roof cover also uses rivets (no caulking) and it even has pre-drilled holes for an easier roof installation.

bathroom exhaust fan vent cover should keep out rain

How Do You Fix A Bathroom Vent Cover If It Is Leaking Water?

When you are inspecting the exterior bathroom vent cover, you want to look for any hairline cracks where water is getting through. Closely look along the edges of the vent cover.

It's also important to make sure that the asphalt shingles aren't damaged around the vent hood. The roofing shingles should be on top of the upper portion of the bathroom vent flange.

It's also a good idea to check the nails or screws where the bath vent cover was installed into the roof sheathing. Water may getting in through the nail heads and onto your bathroom vent.

When you are up on the roof, it is also important to check that the flap is working properly. If the vent flapper is stuck open or is missing, when there is heavy rain, water can easily enter into your vent cover, travel down the hose, and drip all the way down into your bathroom.

Read Also: What Are The Best Ultra Quiet Bathroom Exhaust Fans?

Should I Inspect For Water Damage From A Dripping Bathroom Exhaust Fan?

It's also a good idea to go into the attic, ceiling, or wall (depending on where you bathroom fan is venting) and look for any possible water damage.

If your bathroom vent goes to the roof --- according to the U.S. Department of Energy --- there are a number of signs of water intrusion through your roof and into your attic such as warped sheathing, mold, and wet insulation. You may even have to replace some of the roof sheathing if the water leak has been going on for some time.

When you are inspecting an area for water damage, you will want to look closely for any indications of mold or mildew.

An attic or ceiling cavity is a dark place where mold loves to grow, so when you add in a water source from heavy rain, you may have mold growing on the underside of the roof sheathing or the back of drywall. When released into the air, mold spores can travel all throughout the home.

I highly recommend going into the attic and to inspect the vent hose termination carefully with a high powered flashlight.

Read Also: What Are The Best Bathroom Exhaust Fans With Humidity Sensors?

Should I Install A New Roof Vent Cover?

If your roof vent cover has some cracks, the flapper is not working, or is otherwise defective, it may be smarter just to replace the whole cover with a new unit.

Bathroom vent covers aren't meant to last forever, and they are pretty cheap to replace.

Of course, if you hire a qualified contractor to replace the vent cover, you will have to pay for labor --- probably in the $100 to $250 range just for labor depending on your market, and the details of the job.

Just replacing the cover will be cheaper than having to change the entire hose.

Should I Check My Ceiling For Damage?

If your leaking bathroom exhaust fan has been going on for some time, it may be a very good idea to remove the actual bathroom exhaust fan and check for damage in the ceiling cavity.

There may be damaged insulation, damaged drywall, damaged wood framing, and there may be mold growing.

To remove the bathroom exhaust fan, you will first have to remove the plastic cover by pulling it down, and squeezing the metal clips.

Before you unscrew and pull out the bathroom exhaust fan, you will want to unplug the unit (sometimes there is an actual plug behind the cover) or you should turn off the electricity at the breaker box.

Please do not get electrocuted!

Read Also: How To Vent A Bathroom Fan Into An Attic?

Once you have the power off, just remove any screws holding the bathroom fan in place in the ceiling. When the bathroom fan is removed, you can inspect the ceiling cavity with a flashlight to look for any damage or mold issues.

It is also important to oil your bathroom exhaust fan once a year and now is a great time to do it since it is removed. Check out our guide on oiling a bathroom fan here.

Of course, if the bathroom fan is on the upper level of your home, it may be easier just to go into the attic to do the inspection. Just be careful not compress (ruin) any of the insulation, and make sure that you step carefully and don't go through the drywall ceiling. Be cautious!

Read Also: How To Replace A Bathroom Exhaust Fan Without Attic Access?

Sometimes when we do a DIY job, such as fixing a leaking bathroom fan, we spend a lot of time and money — and then end up hiring a pro to fix our mistakes. That's why I created my Contractor Search Tool, so my readers can get free quotes from local roofers who are licensed and pre-vetted.

I invite you to at least see the pricing from a few trusted roofers—there is no obligation—and then you can decide whether to go ahead with a DIY job. Get your free quotes with my contractor search tool right here.

What's The Bottom Line On A Leaking Bathroom Exhaust Fan During Rainstorms?

It's a pretty bad situation when you have water dripping from your bathroom fan during storms. The bathroom exhaust fan is supposed to remove moisture from your bathroom, not be source of actual water!

Luckily, there is usually a very simple reason for this which is that the vent exterior cover is simply broken or not sealed correctly. Or, heaven forbid, there is a leak somewhere else in your attic and it is leaking onto the bathroom vent hose (but it's unlikely).

Anyways, when your roof is dry, it's important for you or a contractor to get out there as quickly as possible and to carefully inspect the bathroom exhaust fan cover. It may need to be replaced.

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6 thoughts on “Is Your Bathroom Exhaust Fan Leaking When It Rains? (What To Do)”

  1. Hi there,

    We have this exact problem where water is coming through the bathroom exhaust every time it leaks. Can you please guide me what kind of contractor we should be contacting? Roofing contractor or electrical contractor?

    Thank you!

    Reply
    • Hi Mallika,

      If the bathroom vent is leaking when it rains, then you should be contacting a roofer to fix or replace the vent hood (on the roof). In the rare event that it actually goes to a sidewall, then you would contact a handyman or general-skilled contractor.

      Good luck!

      Reply
    • Hi Herb,

      It depends on where the bathroom vent is connect to. If it goes to the roof, then I would contact a roofer because there is likely a problem there. But it could also be a condensation problem if the vent is uninsulated such as when it goes through an attic. Anyways, you need to find where the bath vent starts. For anything other than the roof, you can just find a handyman.

      Good luck,

      Arie

      Reply
    • Hi Debi,

      The cause is going to be the same as leaking bathroom fans if it leaks during rain, basically… the vent cover on the exterior is defective. The flapper may be missing or poorly sealed, or the flashing is damaged. You need to get a contractor or roofer to check out the exterior vent cover.

      Cheers,

      Arie

      Reply

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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping people understand how homes work. He is a licensed home inspector in two U.S states and owns a residential and commercial inspection company (read his full bio on the About page). To ask Arie a question, please use the comment box at the bottom of the relevant article.

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About Home Inspector Secrets

Home Inspector Secrets is an online resource for owners, buyers, and sellers to understand all aspects of home maintenance. We have detailed home guides, product reviews, inspection advice, and much more.