VoyForums
[ Show ]
Support VoyForums
[ Shrink ]
VoyForums Announcement: Programming and providing support for this service has been a labor of love since 1997. We are one of the few services online who values our users' privacy, and have never sold your information. We have even fought hard to defend your privacy in legal cases; however, we've done it with almost no financial support -- paying out of pocket to continue providing the service. Due to the issues imposed on us by advertisers, we also stopped hosting most ads on the forums many years ago. We hope you appreciate our efforts.

Show your support by donating any amount. (Note: We are still technically a for-profit company, so your contribution is not tax-deductible.) PayPal Acct: Feedback:

Donate to VoyForums (PayPal):

Roofing and Siding since 1985
Sat, May 16 2026,10:37am [ Login ] [ Main index ] [ Post a new message ] [ Search | Check update time | Archives: 1, [2], 3 ]
[ Next Thread | Previous Thread | Next Message | Previous Message ]

Date Posted: Fri, Nov 08 2002, 6:41pm
Author: A Roofer
Subject: Re: Roof Vent for muliple washroom vent fans
In reply to: Paul 's message, "Roof Vent for muliple washroom vent fans" on Thu, Nov 07 2002, 8:22am

You state, "It is not uncommon to use 3 or 4 inch PVC piping for bathroom fan applications."

No offense but to my ears that sounds like something coming from either another planet or another place in time. My company is from the greater Seattle area and I have been involved in construction since 1985 when I was 18 yrs old. In the over 1400 homes I have been a part of I have never seen (or have heard of in the trades) a bathroom vent's duct work made from PVC piping. For such venting there is always a "flapper vent" also known as a "fart fan" installed on the roof deck that the duct work attaches to. When the fan is off gravity closes the flapper. I have bought bathroom fans for my own place and have installed them and they never have had anything on them that closed to keep air from coming back in through them. Thats what the flapper vent does. If they all were tied together to the same flapper then they most definitely would blow into each other no matter whether you used a Y or a T to tie them together because the flapper would easily create enough resistance to the flow of air. Hang out on job sites long enough you'll find a building inspector and ask him. He will tell you the same thing. If they just stick PVC piping through a roof for bathroom fan ventilation rain water could run down it in heavy rains and with power running into it this isn't a good idea because of the fact that water and electricity don't mix.

You also state, "The flexible hosing has a greater chance of leakage and humidity and roof trusses don't mix."

More things that don't register with me and my experience.
"chance of leakage" - If they are properly installed they never leak. Its not as the duct work is a moving part that will eventually work itself loose. There are building codes in King and Snohomish County stating the requirements for attaching duct work together and the only time I saw duct work come loose is when the installers didn't follow the local building codes.
"humidity" - Are you referring to insulated duct work or the stuff that is not insulated? There are no humidity concerns with insulated duct work. The humidity concerns can't be that big of a deal because the only thing that the local building codes require insulated ducting for is for the heat ducts. But if it concerns you I suggest you should use it for these vents also.
"roof trusses" - What do the trusses have to do with this?

Thanks for your forum participation and I hope this
adds a little more info for what you were seeking,

Tim Soth / A Roofer

[ Next Thread | Previous Thread | Next Message | Previous Message ]

Replies:

[> [> Re: Roof Vent for muliple washroom vent fans -- A Roofer, Fri, Nov 08 2002, 6:53pm

I also want to add for general knowledge to locals that browse through this posting that in Washington State all PVC piping coming out of the roofs are for plumbing ventilation for draining waste water as I tried to explain in my first post in this thread.

Tim Soth / A Roofer


[ Edit | View ]

[> [> Re: Roof Vent for muliple washroom vent fans -- Paul, Thu, Nov 14 2002, 7:51am

Hey thanks for the info. You're all absolutely correct. I'm a do-it-yourselfer who has a full-time job and 3 kids and just moved into a new house. I'm so exhausted that I started flapping (no pun intended) about an issue that I was obviously confused about. So sorry to take up your time. I really appreciate this great forum and the patience you show towards confused rookies like myself.


[ Edit | View ]


Forum timezone: GMT-8
VF Version: 3.00b, ConfDB:
Before posting please read our privacy policy.
VoyForums(tm) is a Free Service from Voyager Info-Systems.
Copyright © 1998-2019 Voyager Info-Systems. All Rights Reserved.