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db_9 11-11-2009 10:34 AM

How to cut vinyl siding to vent bathroom fan?
Hi everyone,
I am new to this website and need a little help. Currently I have 2 bathrooms on the second floor. Both of the bathroom exhaust fans are currently vented in the attic to the soffit. But they never actually cut a hole in the soffit. They just ran that flex tubing over and sat it on top
of the perferated soffit. My house uses the soffit and ridge vent for attic ventilation. I have read running the bathroom exhaust over to the soffit is a bad idea when you attic is ventilated this way.

So I had an energy audit done at my house. They recommended getting my attic air sealed and running the exhaust fans out the side of the house. There is plenty of room to do this.

But my house has vinyl siding and I am concerned how they are going to install this new vent. I want to make sure it is water tight. Well as much as it can be with vinyl siding.

I plan on asking these contractors how they are going to install this vent before letting them cut holes in my house. If I don't like there answer then I will tell them to forget it.

So what are the steps to properly install a vent through vinyl siding? I have read about vinyl surface mounts???


Ron6519 11-11-2009 03:59 PM

Put the vents through the roof. You don't have to deal with the siding profile and the sidewall vent.

Thurman 11-11-2009 06:28 PM

Venting a bath fan through the roof with a proper roof cap is the preferred method. But-a bath vent fan can be run through a soffitt, again with the proper vent cap. IF you have to run the vent(s) through the wall of the house, the contractor should install a box where the end of the vent will exit. This box has J-channel made onto it for the vinyl siding to mate to, and again, use the proper cap on the end. Good Luck, David

db_9 11-11-2009 08:25 PM

Thanks for the responses. I am just curious why the preferred method is through the roof? I live in New England and we get a lot of snow on the roof. I always wondered how these vents worked when they are covered with snow. Both of my bathrooms are on the ends of my house. So the run to the outside wall would actually be the shortest path to the outside. Shorter than running it up to the roof and shorter than the current run to the soffit.

Is there a problem with just having the contractor cut the hole in the vinyl soffit and adding the soffit vent? It is run over there with the flex tubing. Should I have them replace this with the solid insulated tubing instead? Putting in the soffit vent would be the easiest solution, but I have read stories why it is bad to vent out of a soffit when the attic uses the soffit/ridge vent combination.


oh'mike 11-12-2009 05:45 AM

Punching a hole in the roof is NOT the best way.

Your workers will probably use tin snips and a drill. A little blocking---
Some screws and flexible caulk.

Snow blowing into roof vents and condensation inside the vent pipe going to the roof vent are problems discussed here all the time!

Sound like you have it handled---MIKE---

oh'mike 11-12-2009 05:51 AM

Yes one the insulated duct--Or bury the vent under a blanket of fiberglass insulation.

Condensation inside the vent is a big pain --keep the tube warm with a blanket-Pitch the pipe so and moisture runs away from the fan,if possible.-MIKE-

oh'mike 11-12-2009 05:56 AM

Todays post about roof vents and snow-Snow in through Bathroom Exhaust Vents - DIY Chatroom - DIY Home Improvement Forum

db_9 11-12-2009 08:51 AM

Thanks for the response everyone. I am going to grill the contractors when they show up. I am going to ask the following about them venting it out of the side of the house in the attic.

1. Are they going to use solid insulated tubing instead of flex tubing.
2. Make sure they pitch the insulated duct down so all condesnsation
runs out of the house and not into the bathroom fan.
3. I will ask how they plan on flashing the vent through the vinyl siding.
Now I have read that they should actually take some of the vinyl off
of the house. The vent should have its on built in wall mount which
flashes itself. Then they should put the vinyl back on and screw the
vent into the wall mount.

I have read how some people just blast a hole through the siding and then screw the vent directly into the vinyl siding and then just caulk around it. This doesn't seem like the proper way to me.

What do you guys think?

oh'mike 11-12-2009 09:48 PM

Please don't drive the workers nuts by telling them how to do a job that they are experienced in performing .

Seldom is the siding removed to install a vent cover,I've installed over a hundred of them and never removed the siding.

Relax and learn by watching --Lots of advice on the internet is based more on theory than real honest to god life experience. Take most internet advice with a grain of salt.-MIKE--

Tom Struble 11-13-2009 12:58 AM

these can be used in the soffit instead of thru the wall

sure you can install a vent without pulling the siding and flashing it properly,but i wouldnt

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