Replies

1. 
   Piffin | Sep 26, 2008 03:43pm | #1

   I would use the foam.

   But is this vent pipe metal?

   way too many of these are still plastic, which is a fire hazard.

    

    

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   Taunton University of Knowledge FHB Campus at Breaktime.
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1. 
   user-111700 | Sep 26, 2008 03:58pm | #3

   Thanks Piffin , it is metal. Her handyman refused to do it for her because it says  flammable on the can , but isn't that only until it dries ?

1. 
   FastEddie | Sep 26, 2008 05:39pm | #8

   Be sure to buy the low-expanding foam, or you might collapse the duct.  And if it is visible on the exterior, you will need to paint it to prevent uv-breakdown."Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   Norman | Sep 26, 2008 05:49pm | #9

   I hate the low expanding foam, which never really dries or sticks to anything. Used sparingly and in repeated passes, I have never had a problem with the regular version. If the foam can release its excess expansion to outside or into the wall void, I doubt there is any risk of collapsing a metal duct.

   And as the other post suggested, do paint the stuff after it dries, cuz sunlight turns it crumbly.

   Good luck.

2. 
   Piffin | Sep 26, 2008 08:54pm | #13

   The propellant is highly flamable, but the cured foam is no more flamable than the other materials you might surrond the pipe with normally, such as plywood or caulk. In high heat, it will flame or give off toxic fumes.But that is when there is already a fire in the line. Normal operating temperatures for a dryer will not hurt it. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   arcflash | Sep 26, 2008 03:56pm | #2

   Check the can. It should tell you maximum temps. I used the stuff for my dryer vent run and so far, the house hasn't burned down. Buy some mineral spirits. You are bound to get that stuff where you don't want it.

3. 
   MarkH | Sep 26, 2008 04:26pm | #4

   I believe the foam is OK, but I would probably get a piece of plywood or drywall etc. and cut a clean hole for the pipe to exit, and attach it to the wall to cover the gap.

   Is this house in Lakeside Ohio? Friend has a cottage there. Beautiful place to go to.

1. 
   user-111700 | Sep 26, 2008 04:35pm | #5

   Thanks for the advice. We are in Geneva on the Lake. Its a beautiful day here.

4. 
   Clewless1 | Sep 26, 2008 05:13pm | #6

   The building official might be another stop if you are comfortable with them. I'm guessing the foam should be good as there is usually no issue of placing dryer vents in the vicinity of passersby .... and I'm guessing foam is good to maybe 200 degF.

5. 
   BUIC | Sep 26, 2008 05:37pm | #7

     Foam can burn when exposed to an open flame. The heat of a dryer vent doesn't come close, so there's no problem.

     It'd be like making tea and setting the used bag on your napkin, and worrying that the hot tea bag could cause it to burst into flames because the napkin is "flammable".

        Never hurts to check about things, but you're okay with this...buic

6. 
   DanH | Sep 26, 2008 07:31pm | #10

   The foam should be reasonably safe once it fully hardens (several days). It does in theory need to be covered with something (preferably drywall on the inside) to serve as a firestop and to keep weather away from the stuff. If you're really nervous you can buy special firecaulk foam.

   Another option is to stuff around the vent with bits of fiberglass insulation.

   There is no absurdity that human beings will not resort to in order to defend another absurdity. -- Cicero
7. 
   DanH | Sep 26, 2008 07:34pm | #11

   Another option, where you only want to seal small gaps and not insulate, is to use "duct seal", a type of putty used by electricians. (Comes in a "brick", like modeling clay.) It can be easily formed and put in place by hand, is fireproof, and is weather-resistant. (Any decent hardware store should have the stuff.)

   There is no absurdity that human beings will not resort to in order to defend another absurdity. -- Cicero
8. 
   MikeHennessy | Sep 26, 2008 08:21pm | #12

   Foam, covered with a piece of flashing with a dryer vent-sized hole in the center, on the outside.

   Mike Hennessy
   Pittsburgh, PA