Unique attic ventilation problem

Old 10-06-08, 12:01 PM
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Unique attic ventilation problem

I have a Mansard Victorian style roof which is presenting a problem for ventilating the attic. The first problem is that the attic currently has NO ventilation. It also has a bathroom fan venting directly into the attic space. I want to remedy this, but I'm not sure what the best approach is.

My VERY BASIC understanding is that I need vents on the ridge for the air to flow out, and soffit vents along the sides to allow fresh air in. Problem is, the soffits on a Mansard are actually below the second floor of my house, and so are 10' removed from the attic space. There are no gables either. It's a small attic, about 25x25 feet, 6 feet high in the center and sloping down to the edges at about a 30 degree angle.

How should I ventilate this attic keeping in mind that I have no access to the soffits and my roof has no gables? Is there some kind of fan I could install to exchange the air?

Old 10-06-08, 12:56 PM
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attic air

I am not sure how your house got built without some sort of ventilation but if the air has a way to go through the rafters the soffits being 10 feet away is no problem then because you have no gables you put venting under the ridge cap they sell ridge vent at HD and Lowes.
Old 10-08-08, 02:05 PM
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It sounds like the trickiest part would be providing a continuous air channel from the soffit area (which is below that floor's floor level) to the ridge area. One idea would be to gut those walls, install air baffles designed to sit on the underside of the roof decking between the rafters, and then cover the baffle with insulation and drywall. Then, up in the attic, have the baffle feeding air from the soffit cavity area to the open attic/ridge area. (Optionally, just continue the baffling/insulation scheme right up to the ridge vent.) Just be sure every area of roofing between rafters is getting a channel of air passing it.

Doing it this way would probably be a big job if you have finished walls on the inside of that Mansard roof...

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