Replies

1. 
   PatchogPhil | Sep 18, 2007 11:47pm | #1

   Funny you mention this.  I just logged on to here to post a question directly related.

   Saw a Holmes on Homes show and they foam sprayed the rim joist and short foundation wall inside of a crawl space (blue colored foam).  Then they sprayed over that with something (grey) that is supposed to protect the foam from burning and making toxic smoke.  They didn't mention what the grey stuff is called.  Looked like wet-spray cellulose.

   Any one know what it could be?

    

    

    

   Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?
   

1. 
   renosteinke | Sep 19, 2007 01:22am | #3

   I cannot say, with any certainty, what product was used. There are now several products marketed (most claim to be clear) that are what I call "magic paint," and are, IMO, a fraud. I do not believe they contribute anything to fire resistance. If the coating you saw had substantial thickness ... say, more than half an inch .... then it was likely a cementitious product, that does provide significant fire protection.

2. 
   renosteinke | Sep 19, 2007 01:18am | #2

   When foam burns, it does produce an exceptionally annoying, greasy smoke. Oddly enough, the addition of 'fire inhibitors' to the foam seems to make the smoke even more annoying.

   Is it toxic? Is it more toxic than, say, wood smoke? The fact is, we really do not have any truly scientific way of knowing. This is why there are no 'toxicity' standards for smoke. We have neither a working definition, nor the means to measure such a thing.

   The 'smoke ratings' you see on some products' labels are based simply upon how much light is blocked by the smoke produced in a test burn.

3. 
   timkline | Sep 19, 2007 01:33am | #4

   I can assure you that the toxicity of the smoke from the foam burning is the least of your worries in a house fire.

   All of your personal belongings in the home once on fire will be producing smoke far richer in toxins. Generally your personal stuff is much more prone to burn than foam buried in the walls.

   I wouldn't use this as a consideration in your decision about the use of foam, although I feel that if used, the foam should be protected by a material such as drywall from direct flame contact.

    

   carpenter in transition

4. 
   mackzully | Sep 20, 2007 05:48pm | #5

   What season episode was that? (I'm working on getting down the complete seasons 1-4, but have only watched through half of two).

   They might have used an intumescent paint such as this:
   http://www.contegointernational.com/products_3.cfm

   Or they might have used a cementious gypsum coating, which when sprayed on, looks exactly like cellulose insulation. Basically the gypsum contains anywhere from 15-25% water content that is sacrificially released during a burn (i.e. exactly the same process that gives drywall its fire rating). I have it sprayed on to the ceiling deck here at my office (bare ceilings) and it's not bad, but very friable, so not for anywhere it might get bumped.

   Z

1. 
   PatchogPhil | Sep 21, 2007 05:49am | #7

   I'm azzuming you meant to ask me......  not sure what year HoH episode.  DirecTV TiVo many times doesn't show the year of the show.

     

   Quantum materiae materietur marmota monax si marmota monax materiam possit materiari?

5. 
   frenchy | Sep 20, 2007 07:35pm | #6

   Grantdawg

     Well you really are asking the wrong question..

     You see no foam should be put on without sheetrock protecting it..  that's code..

    Once you put foam  on with it's attending sheetrock you've dramatically reduced the chance of it catching fire..

    The foam disapates the heat in a way that no other insulation will..

     A lot of tech stuff could follow, blah blah blah.

      I'd love to bore you with details if you'd like..