bathroom fans - should they vent through the roof?

[Anonymous]

Ours go into the attic and out the side.

[Anonymous]

Our home was built in the mid-1980s and the bathrooms vent to the attic. Home inspector did not flag this, but but said the dryer vent that went to the top of the attic and not through the roof was an issue. A couple of years later, our condo board required corrective action on the dryer vent but not on the other vents. The attic is not a fully enclosed space.

[Anonymous]

Interesting PP. In the case of our old fans venting into the attic, the ceiling paint in the bathrooms is now peeling. It’s frustrating!

[Anonymous]

Anonymous wrote:Sorry if this is a dumb question! We purchased a home built in the 60s and the bathrooms have fans that don't seem very effective. When we looked in the attic, they appear to be venting through an open tube straight into the attic. Should they actually vent through the roof? If so, what kind of person should I hire to do this kind of work?

We have the same problem. We are renovating bathrooms and replacing them with stronger fans that go to the roof. Contractor said they should.

[Anonymous]

Anonymous wrote:Interesting PP. In the case of our old fans venting into the attic, the ceiling paint in the bathrooms is now peeling. It’s frustrating!

It might be a paint issue? Or maybe your vents are too old (to not circulate the air enough). My husband takes frustratingly long showers, we’ve been in our place for 8 years are the paint issue still ok.

[Anonymous]

Chatbots are perfect for these sort of questions

For a bathroom exhaust fan installation, there are a few acceptable options, but venting through the roof is generally considered the best practice. Let me explain the main approaches:

Best option - Through the roof:
- Provides the most direct path for moisture to exit
- Prevents condensation from dripping back down
- Less chance of moisture accumulating in the attic
- Allows water vapor to immediately exit the house

Acceptable but not ideal - Through soffit/eaves:
- Can work if properly installed with insulated ductwork
- Must ensure proper slope to prevent water poolback
- Should terminate at least 3 feet from any soffit vent intake
- More complex installation to maintain proper slope

Not recommended - Terminating in attic:
- Can lead to mold and wood rot in attic space
- Moisture can condense on roof sheathing
- May cause insulation to become wet and lose effectiveness
- Violates most building codes

Key installation tips regardless of route chosen:
- Use insulated duct to prevent condensation
- Keep duct runs as short and straight as possible
- Ensure proper slope (1/4 inch per foot minimum)
- Install a proper vent cap with backdraft damper
- Seal all duct connections with foil tape

Would you like more specific details about any of these approaches?

[Anonymous]

The chatbot is wrong.
Any time you make a perforation in the building envelope you run the risk of creating a leak. That risk is highest in the roof and lowest in the soffit.

If there is no other alternative the roof is acceptable but it's not preferable.

[Anonymous]

Anonymous wrote:The chatbot is wrong.
Any time you make a perforation in the building envelope you run the risk of creating a leak. That risk is highest in the roof and lowest in the soffit.

If there is no other alternative the roof is acceptable but it's not preferable.

House built in the early 90's upstairs fans that came with the house weren't even run to the soffit. Had an electrician install a fan/light in my bathroom last year. Roof guy came in and said nothing was connected and they would not run the venting through the soffit, MD code doesn't permit it in the 21st century. I have extra roofing material which he used to run it through the roof and properly seal.

Maybe in VA you can still run it through the soffit or if you do it on your own. Maybe you can talk your electrician into doing it that way in MD. You may not be able to talk an electrician for hire from a company into doing it in MD or other states that have similar code requirements.

[Anonymous]

You definitely need to correct this. The question of how to vent it outside the envelope is one where you need to balance two issues: 1) length of the duct, 2) location and ease of maintenance.

Ideally, you'd never vent through the roof because it is difficult to access the vent termination and clean it. Yet, if there is a long run to get to a wall or gable end, it may be better to run to a roof vent. You might also be able to vent out and down through the soffit (and if it is near a window then you can open the window to access the vent and clean it).

DO NOT allow anyone to install flexible hose as it will cause you more trouble than it's worth. Note that ducts running in your attic--usually an unconditioned attic--run into big issues with internal condensation. If they are effective at removing the warm, moist air, that air can condense in a cold pipe running through the attic. Dust, hair, lint, etc. will cling to the duct work and build up. So make sure it is galvanized or aluminum rigid pipe and make sure it gets insulated and sealed with the proper duct tape (not "duck tape" or the gray stuff but actual duct tape an HVAC installer would use).

[Anonymous]

I think you're confusing what he said.

It used to be common to vent into the space above the soffit. That is no longer allowed. You can vent through the soffit, ie the exhaust goes to the exterior below the soffit. Depending on how the soffit and roof are constructed there isn't always space to do this.

[Anonymous]

Anonymous wrote:I think you're confusing what he said.

It used to be common to vent into the space above the soffit. That is no longer allowed. You can vent through the soffit, ie the exhaust goes to the exterior below the soffit. Depending on how the soffit and roof are constructed there isn't always space to do this.

If you're referring to me, 18:02, I'm not sure how I am confused, and I think you are misinterpreting me...I said (about soffit venting): "You might also be able to vent out and down through the soffit (and if it is near a window then you can open the window to access the vent and clean it)." I said "out and down" meaning not into the soffit cavity but with an exhaust termination on the surface of the soffit and having the exhausted air blow out into the open atmosphere. You should never vent into an enclosed space since it will just build up moisture

[Anonymous]

No. You will get mold in the attic.

[Anonymous]

Bottom line anything will be an improvement to your current situation of venting into the attic.

[Anonymous]

Anonymous wrote:

Anonymous wrote:I think you're confusing what he said.

It used to be common to vent into the space above the soffit. That is no longer allowed. You can vent through the soffit, ie the exhaust goes to the exterior below the soffit. Depending on how the soffit and roof are constructed there isn't always space to do this.

If you're referring to me, 18:02, I'm not sure how I am confused, and I think you are misinterpreting me...I said (about soffit venting): "You might also be able to vent out and down through the soffit (and if it is near a window then you can open the window to access the vent and clean it)." I said "out and down" meaning not into the soffit cavity but with an exhaust termination on the surface of the soffit and having the exhausted air blow out into the open atmosphere. You should never vent into an enclosed space since it will just build up moisture

I was replying to 17:46 who said that venting through the soffit wasn't code.

But I've never had to clean the grill of an exhaust fan other than a dryer.

[Anonymous]

Just get a handyman and get it vented through the roof - don't worry about all the noise above.