bathroom overhaul


Old 05-18-06, 07:48 AM
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bathroom overhaul

We need to install an exhaust fan in our very small bathroom. It's a one level house with no attic. Is it better/easier to go through the roof or the exterior (brick) wall? Also, is there a way to wire the fan to the main switch, which is on the opposite wall, without ripping up the wall to do it? If not, can you suggest a "least destructive" method to do that? THANKS!
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Old 05-18-06, 04:23 PM
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Gee. All those views and no replies?

Is your bathroom circuit on one 20 amp breaker, rather than a 15 amp breaker? And can you identify every single thing on that circuit? First, do that. See if your light, operated by your switch, is on that same circuit. If not, and it is on some other circuit, this could actually maybe be fortuotous. Depending on code, you may be able to tap the light box and bring romex from it to the ceiling fan location. We do this all the time in rentals. We want it that way so that college kids HAVE TO have the ceiling fan on, when they are in the bathroom...when the light is on. If we didn't do this, and it was on it's own switch?...they wouldn't use it because of the noise.

Oh...and through the roof would be much easier than trying to go through the brick. Some people, though, have effectively vented it by hanging it in the attic under one of those mushroom vents, or by drilling a 3 or 4 inch hole in the eave's soffiting. But the best method is by having it directly vented outside and preferably not under the soffit where in theory, the updraft entering the soffit could pull the exhausted steam right back into the attic. But it's your call. I have seen it done various ways and I myself have 'cheated'? in some of the ways mentioned, with no ill effects.

If you live where the climate can freeze....When exhausting through the roof, you want a fairly straight shot to minimize the amount of ducting that can condense and run back into or around your bath fan and cause water damage. If you go vertical and use rigid, wrap and tie fiberglass insulation around it. If you use flex, I recomend you use insulated flex. If you vent it in the attic horizontally (so you can exit by soffit or an exterior gable end wall... either again wrap solid duct with insualtion... use insulated flex...or...bury the ducting in the insulation. If you bury it in such a fashion between the joists, you are fine. But if you go up and over joists, I would not recommend this burying method because someone could go up there sometime and step on it and crimp it. Not unless your bathroom/fan location is in some obscure corner of the attic.

The reason for insulating the horizontal run is....well, years ago, I got a call from someone whose flex ducting draped across the top of the attic, and held moisture and froze. It literally filled up completely with water that froze, and the ducting felt like it weighed a hundred pounds! Solid ice. Seriously. I had to get rid of it... and then I went to insulated flex.

While I am on this topic: On another rental I got called for their dryer no longer venting effectively. It turns out they vented the dryer by a long flex duct suspended under the floor joists in the basement for about 20-30 feet before exhausting out the rim joist of the house. The moisture from the drying process condensed in the basement and the flex duct swagged under the weight. The worse it got, the worse it got. It filled up completely with water in a couple of the swagged sections, blocking off the airway.

Last edited by DaVeBoy; 05-18-06 at 04:46 PM.
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