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Posted by: from Saint Leonard
5/23/2012 at 3:14:27 PM

Hi from Montreal.

I just installed a bathroom fan on my second floor appartment and before i close the ceiling i like to make sure i did'n screw up, here is my question if i may.

The house is a duplex with a flat roof. There is about 10" between the ceiling and the roof. The bathroom has a window facing a skylite shaft 3x5 feet that goes from the first floor to the roof with a pyramite skylite on top. The window in the bathroom is closed.

What i did is vented the 4" pipe into the shaft on top of the window, from there a 45 and than a streight 20" pipe to a roof jack in the skylite. So far i have insulated the pipe in the ceiling with a sleeve i bought a HD. I put some fiberglass insulation, pink one, around and on the side of the fan.

My question is, how much of insulation should I put since there is enough room around the pipe also how much around the fan?

I am asking all this because I noticed the pipe 5 feet long is sloping towards the fan, about 1". It's killing me.

Any help is appreciated.

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Date/Time5/23/2012 at 9:50:33 PM

Im not sure from your description, but you have vented the fan completly to the outside right? If not you are going to have major problems.

There is no such thing as to much insulation, just make sure you leave about 2" on top for air flow between the insulation and the bottom of the roof sheathing.

Also a vapour barrier between the drywall ceiling and the insulation, also run the vapour barrier around the fan housing (box). Having it sloped to the fan is good, if you have water running from the fan it will tell you if there is a problem, rather than it rotting out the ceiling were you can't see it untill it's to late.

If you insulate properly, water won't be a problem.

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Matt in Saint Leonard
Date/Time5/24/2012 at 11:18:17 AM

Thanks James,

Your answer is just what i needed.i left space between insulation and the roof and put some around the fan.

As for the vapor barrier, when my wive called broune the said over and around the fan, he never mentiond vapour barrier. maby i should call again,just to get his take on that.

tks again

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Matt in Saint Leonard
Date/Time5/24/2012 at 11:24:55 AM

Oh i forgot. yes i am going to the outside. right now the pipe is comming out in the shaft, now i just have to connect a 45 than 20" straight to te roof duct witch is removing a pannel from the skylight and replace it with a plexiglass.

I have talk to someone that builds skylights and he says that this is common. In fact the charge about 500 bucks for this work.

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