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Whole House Fan Venting Issue

The Home Wizard app calculates your ideal home care program to avoid problems with your Whole House Fan, but sometimes trouble can still occur. Here are answers to questions about whole house fan venting issue.




Dear Martin:

Thank you for your patience. If it helps, the upgrades that we are working on will help keep Home-Wizard a free service (we are upgrading our Sponsor Dashboard and expanding the recommended tasks to include operating tips and home improvements, plus expanding Home-Wizard to apply to rental houses, summer homes, townhouses, condos, apartments, etc.).
We had everyone working all weekend (again!) and hopefully we can make our schedules. But getting to your questions . . . It's good that you have a roofer coming, and you should check with them about venting your bathroom fan through the roof, rather than the soffit. When you say "vent out to the soffits," I assume that your vent doesn't just go through your attic and stop at the soffit (on the inside), but rather that it goes all the way through the soffit and vents completely on the outside, right?
However, even if your vent goes completely through the soffit to the outside, the problem is that venting very moist air from a bathroom fan into a roof soffit can still allow the moist air to be drawn up into the vents of the soffits around where the vent comes out, and this moist air being drawn back into your attic could be what is causing your mold problem in your attic.
While your roofer is there and can physically inspect and see your actual situation, you should ask them if they can install a vent through your roof, away from your soffit, so that when the moist air is discharged from your bathroom that it discharges to the outside where it cannot come back into your attic, and if there is some condensation, it will land on your roof shingles (which are designed to handle moisture).
Regarding getting rid of the mold that has started growing in your attic from when the moist air from bathroom fan was getting into your attic, of course you will want to first stop the moist air from getting into your attic and ensuring that your attic has adequate ventilation (this is something else that the person you have coming out to look at your roof can evaluate). But as far as actually removing the mold that is there in your attic, I would strongly suggest that you consider hiring a professional to do this.
If not done properly, you risk stirring up the mold and having it drawn down into the living spaces of your home where you can create some MAJOR health problems. If it helps, here is a webpage that describes the process that a professional would use to remove mold from an attic, and some of the risks: (we are not recommending this company, just providing the link to their site's information)
Also, when your roofer is there, you can ask them about properly insulating your bathroom vent pipe that goes through your attic, so that you don't get condensation when the warm pipe hits your cold attic air in the winter. This insulation should be the spray-on type, as just wrapping with soft insulation can come loose when duct tape gets warm in the summer.

I hope this is helpful. Thanks again for your patience.

Whole House Fan