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Moisture in Attic

We moved into a 1976 garrison colonial in New England earlier this summer. The previous owners tried to do a lot themselves but it usually created more problems. One example of this is in the attic. The attic always seemed a bit damp - even with windows slightly open on each side of the attic. Recently i was up there and noticed when touched the wood roof sheathing it was damp (Roof is only a few years old). Some of it was turning black. It only seemed to be damp on one half of the roof (part that doesn't get sun). When I looked down I found that the exhaust fan from the bathroom just vents right up into the attic. We never use this fan but moisture from the shower can simply make it's way up to the attic.

Question - there is a pipe from the shower that leads to the main stack of the house that goes right by this - can I tap into this and route the exhaust into this? (i'd rather not cut a hole in the roof). Or should I try to vent it out an attic window (20 feet away). Or better yet - should I simply just replace the vent w/ a non-venting light?

I'm hoping this is the cause of the moisture in the attic. Moisture problem aside - should i be leaving these windows in the attic (one on each side) open during winter months for (say an inch or so?) for ventilation?

Re: Moisture in Attic

I wouldn't tap into the stack as you might get unpleasant wafting back through the fan. If you don't use the fan, then you must not need it. Easiest is just putting light in.

Re: Moisture in Attic

The fan shouldn't be vented to the attic, but if you don't use it I doubt it is causing the moisture. Are other vents going to the attic?
I would say you need more ventilation than just opening the windows a bit. Ventilation is still needed in the winter to get rid of frost & condensation that will form on the underside of a roof.

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