I am disconnecting a bathroom exhaust fan that is vented to a roof vent in my attic. This caused condensation/moisture in my attic, which became apparent on these cold winter days. Some of the insulation is damp( I plan on replacing what is apparently damp). There are no signs of mold at this time. What do I need do so to don't have mold/rot problem in the future? Do I need to be concerned about the second floor ceiling drywall?
Bathroom exhaust venting to a roof vent
bathroomexhaust-fanmoldventilation
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Cutting a hole through brick is no big deal. You could use one of these as a disposable hole saw for $20:
Or one of these as the "right" tool, which will be reusable for $75:
Most hole saws require a 1/2 inch drill plus a ~$10 arbor, both of which will be very useful for other projects in the future, like installing door knob sets in new doors, installing plumbing, ductwork, plenums, and all kinds of projects in plywood, sheet metal, lumber, plastics, etc.
When making the hole, take care to slant it slightly downward (2%—1/4 inch per foot—is typical) toward the outside to prevent rain, etc. from finding a path indoors. Install a vent device with a damper to prevent hot/cold air from coming inside when the fan is not on, and seal the hole at the outside surface thoroughly with silicon caulk.
Slate can be cut by this type of blade too, but holes through the roof are often fussier to make leak free.
In an apartment building they may have deliberately designed that area to function as a plenum space. That design would -- one hopes -- include selecting/arranging building materials that could tolerate the moisture these fans would pump into that zone.
In your house, it's less likely that folks made the appropriate effort.
Rot isn't the only issue. At best, more moisture in your insulation will mean it insulates less well than it should. I don't know enough to have any valid opinion on whether the fact that you have the spinners to help actively encourage airflow will make up for that.
Personally, I'd say either fix these to exhaust to outside, or at least spend a bit of money to get an expert opinion on whether you can get away with not doing so.
(One of my bathroom vents exhausted into the attic. My inspector, an old-timer, grumbled but didn't actively recommend fixing it. My insulation contractor took one look at it and said "I'm fixing this.")
Related Topic
- How much heat loss through bathroom fan vent
- Roof Ventilation and Insulation – Midwest – Gable and Ridge vents only, no soffit vents
- Shower in one bathroom causing moisture in the second
- Finding Mold After Roof Leak
- Do we need a gable vent, and in either case, how to vent bathroom fan outside (can it be via the gable)
- Fixing a bathroom vent exhaust going only into attic
- Are there issues with venting a bathroom fan through the roof soffit
Best Answer
As Ed said in his comment, you need to reconnect your exhaust to the roof vent. Perhaps your question should've addressed that issue. It's not clear why you made that move.
I also agree that the insulation will probably dry out well with a little air movement. I'd place a fan blowing across the surface of the damp area, and be sure that you have good outflow. Apply a fan to a roof vent for a few days if necessary.
The drywall isn't an issue either, unless you have visible signs of water damage or mold. Even mold on the attic side wouldn't motivate me to tear it out.