Testing Bathroom Exhaust Fan Venting

[clawbennett]

Hello! Here's my situation....

We have a 2 story house with walkout basement. There are 4 bathrooms in the house. All of the bathrooms have exhaust fans installed in the ceilings, but the issue is I can not access anything other than the fan itself to see if they are properly vented out of the house and not just in the walls.

We are noticing a lot of humidity and condensation building up even with the fans running during showers, etc. It's so bad it escapes into the bedroom and hallways. I have also discovered over the past year (since we moved in) mold starting to form on the ceilings and walls just above the showers in two of the bathrooms.

Is there a way to test to see where the fans vent? We have stacks on top of the house, but I am not sure what they are for, or what I am looking for exactly in regards to exhaust fan venting. I do not have access to the vents on the roof nor do we have an accessible attic space. Our house was built in the mid 90's by the previous homeowner. He did all the work himself, and we already know that most of the work he has done is NOT to code. We've already had to fix a ton of problems and fire hazards.

Thanks for the help!

 

[ImOld]

The exhaust vents will have hoods/caps of some sort over them to keep out the elements. See if you can open up one of fans and check if there is anything on the exhaust port at all. Sure doesn't sound like it. I predict an attic access in your future.

 

[Sponsor]

 

[clawbennett]

Ok. Just took a picture outside. The basement exhaust is vented. Turns out they are venting the basement exhaust fan to a furnace duct that exhausts outside through the wall.

The attached photo shows the only vents on the roof. Ironically both of these are in fact positioned over/near bathrooms. However, the bathroom we have most concern about in the main floor (master bath) has no venting above it obviously. And unless they tied this exhaust fan ducting somehow to these vents which are quite a ways apart, not sure how to track it.

I also found out these are 50/60CFM fans and the bathrooms are mostly 75-100sq ft. So they’re inefficient to begin with.

 

[WorthFlorida]

I hope you took care of the basement vent fan. Luckily you didn't get carbon monoxide poisoning. On a guest the pipe with the elbows on them must be the exhaust vents for the fans. Probably rain water was getting into the pipe dripping all the way into the bathroom. Also it would not be a rigid pipe for a bathroom exhaust vent unless this was the only way to do it with a metal roof. For this you would want a roofer to fashion in the correct exhaust since you're dealing with a hole in the roof and its sheet metal. I do not know if there is one made for metal roofs.

The first floor roof, is there a garage sharing the roof where you could look into the attic space from the garage attic?

If you replace the exhaust fans go with Panasonic brand, they are nearly dead quite and move a lot of air. I have wall timers on mine up to one hour on time with auto shut off. For access to the attic is is very easy. It's only drywall and cutting a 24" square hole between the rafters is easy to do. If there is a walk in closet that is usually the best location for one.

In the meantime, as the weather cools and more chance for condensation, place a tower or pedestal fan outside the bathroom doors. I have one of these for my 2nd floor bathroom with the world famous Nutone fart fans, more nose than function. Many fans have built in timers and some with remotes. I run my 1 hour every time I use the shower. By moving the air it drys the damp walls and ceilings of condensation.