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Donald Wall
10-23-2007, 02:47 PM
clothes dryer was venting thru roof vent. The current vent cap is held on with self tapping screws and is positioned so low that it restricts air flow. I found a simular shaped vert cap that is riveted to a 3" dia sleve.

Question: When attaching the new vent cap assembly to older existing dryer vent duct, would you use a silicone sealent? Can 181B-FX duct tape be used on this outside application.
Billy Stephens
10-23-2007, 04:00 PM
clothes dryer was venting thru roof vent.

Question: When attaching the new vent cap assembly to older existing dryer vent duct, would you use a silicone sealent? Can 181B-FX duct tape be used on this outside application.
Donald,
#1=No!!

#2=no, It's not UV Rated.
Rick Hurst
10-23-2007, 04:14 PM
Dryer vent on the roof should have a damper, and not be vented through a roof vent used for ventilation.
Jim Luttrall
10-23-2007, 06:51 PM
This is typical of this area. Make sure the screen is removed when used for a dryer.
Jerry Peck
10-23-2007, 08:19 PM
Here is a cross section of a dryer vent roof cap, they should have the neck sticking down, made as part of the roof cap, onto which the dryer exhaust duct fits and is sealed.

Fantech: Accessories - Exterior Vents (http://www.fantech.net/accessories4.htm)

The dryer exhaust duct *should not* just go up into a roof vent cap and be sealed/foamed/whatever around.
Michael Thomas
10-24-2007, 06:41 AM
For reports, if anyone wants them:
Joel Mizrahi
10-26-2007, 11:32 PM
Roof mounted dryer vent (gas fired) with screen. This photo was taken at a 9 month old townhouse unit.
Adam Horowitz
09-13-2008, 08:11 AM
This is typical of this area. Make sure the screen is removed when used for a dryer.

Is there a better/different screen to use instead? I worry about bees, etc getting in.
Scott Patterson
09-13-2008, 08:42 AM
Is there a better/different screen to use instead? I worry about bees, etc getting in.

The damper will prevent that from happening. This is why you have to use one with a damper on it and not the screen
Jim Luttrall
09-13-2008, 08:55 AM
The integral back draft valve will stop bees, air, etc. as long at it works. One sure fire way to make sure it stops working is to leave the screen in place.
There is 100% probability that screens on dryer vent terminations will stop up with lint and a very small chance that bees will find their way into a dryer vent termination that does not have a screen.
Clogged dryer vents cause fires, never heard of bees causing a fire.


2003 IRC
M1501.1 ... Screens shall not be installed at the duct termination.
...Exhausts shall be equipped with a backdraft damper.
Jim Luttrall
09-13-2008, 08:58 AM
From yesterday's inspection.
Adam Horowitz
09-13-2008, 09:16 AM
The integral back draft valve will stop bees, air, etc. as long at it works. One sure fire way to make sure it stops working is to leave the screen in place.
There is 100% probability that screens on dryer vent terminations will stop up with lint and a very small chance that bees will find their way into a dryer vent termination that does not have a screen.
Clogged dryer vents cause fires, never heard of bees causing a fire.


Hi guys,

Great feedback. I'm not sure that I know what is meant by an "integral back draft valve"? Is that the same as a damper?

I've seen these mostly:

http://www.inspectionnews.net/home_inspection/attachment.php?attachmentid=3343

They have a damper in them. It sounds like most are in agreement that these will keep critters out. Do you have to worry about squirrels, birds, etc with not screening?
Adam Horowitz
09-13-2008, 09:19 AM
From yesterday's inspection.

Wow - scary stuff!
Jim Luttrall
09-13-2008, 10:13 AM
Hi guys,

Great feedback. I'm not sure that I know what is meant by an "integral back draft valve"? Is that the same as a damper?

I've seen these mostly:

http://www.inspectionnews.net/home_inspection/attachment.php?attachmentid=3343

They have a damper in them. It sounds like most are in agreement that these will keep critters out. Do you have to worry about squirrels, birds, etc with not screening?

Yep, damper, flapper valve.

You have to worry about squirrels on anything, very destructive creatures. Where possible keep them off the roof. The will gnaw on sewer vent flashings, eat their way into attics, gnaw on wires, etc.
Generally though, I have not seen them be a big problem on dryer vents.