The flexible pipe for the exhaust fan is vented in to a vented soffet. I am geeting condensation build up on the plywood in the attic should I extend the pipe so it vents to the outside of the soffet or do I need to vent it out the roof? The flexible pipe that was used is not tin but plastic, should I change the pipe?
Your vent pipe to the soffit vent should be replaced with an aluminized flex vent and it should be connected to a soffit vent directly or vented directly to a roof vent made for that purpose with no gaps and sealed with foil tape.
First, an articulated metal vent pipe would be best, both for longevity and greater airflow. I don't meant the cheap aluminized accordion dryer vent hose, but full steel piping that is articulated and flexible. As for the actual venting, since the hose is already in the soffit area, you can install a specific vent cap that is designed to be installed on the underside of the soffit area. A proper vent cap will also have spring loaded flaps to keep the ducting closed when the fan is not running. Like this one (mounts to the underside of the soffit):
Home Depot carries this (or at least did).
You should not that there is a school of thought (valid) that says you should not vent bath or dryer exhaust under the soffit as the moist air can then be drawn up through the regular soffit vents (for the roof bays) and up under the roof sheathing. The contrary to this is that if the roof and soffit are properly vented in the first place, this will not be a negative issue.
It is the most important thing in the bathrooms without Venting fans it is just impossible to stay about a minute in the bathroom.
I agree with you Paul. It's a must to have an exhaust fan in every bathroom.
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While some good advise has been give here there are certain things for further consideration. The current venting conditions are not going to improve unless you re-rout the to a much better location. The reason for vented soffit is that it allows air to enter the roof area through convection. This is not allowed in the International Residential Code and for a good reason. This allows the warm moist air from a shower to be pulled in to the roof area just above and this can and will in most cases cause the problems you described
The recommended location would be a side wall (gable end wall). if you have a hip roof and no such walls then through the roof is the only option left. In any case, make sure to eliminate any vertical run of pipe. If you have to have a rise in the pipe, make sure that you create a dip just after the fan. If not in the winter the warm moist air will create condensation on the walls of the piping and fall back to the fan and on to your ceiling. This condition is existing if you see staining around the fan. Hope this helps!!
Vent your bath and kitchen exhaust fans through the roof through a special roof hood. Venting through a roof vent or exhausting them in the attic could cause moisture problems and rot....
Make sure that when you install the duct, it slopes slightly downward towards the outside. This way condensation build up will run towards the outside of the building.
So glad to know that a soffit vent isn't so weird...I'd never seen one before we bought this house. So is it a good idea or not? I'm not particularly fond of it in the winter. We have harsh winters here and we get an ice block on the patio where the vent dumps.
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