I wanted to know if anyone had any experiences using the bubble wrap w/ the double sided radiant barrier.

I had a weird experience thanks to a fire pit, my Brother-in-Law, and a few beers.  My Brother-in-Law made a make shift pot holder looking glove and held it about 8" away from a pile of extremely hot embers.  After nearly a minute the glove started to smoke because the exterior nearest the fire was starting to melt.  Despite this, he said the inside never got that hot.

What I am figuring is that, if this material works this well with such extreme temperatures, why wouldn't it be useful in a knee wall area?  It would be a lot easier to install than rigid foam board and much easier to squeeze through a small access hole.

 

What do you guys think?  Do you have experience using this material? (Keep in mind I live in Atlanta, GA, not New England).  Thanks!

Tags: Insulation, bubble, heat, knee, transfer, walls, wrap

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Remember, a radiant barrier only reflects radiant heat.  The fire test your brother in law did was the ideal test for that material, since essentially all the heat was radiant, but in an attic situation that's not the case.  For the radiant barrier to work, there has to be an air space between the barrier and any other objects (to rule out conduction), and its surface has to remain clean and shiny (no dust collection).  So would it help in a kneewall area?  Maybe a little, but not as a replacement for insulation.
I get your point, but I am talking about using it in addition to the existing insulation.  The most common treatment here for knee wall problems is to seal the penetrations from the attic side of the wall, push the batts (usually R-13 here) back into place and then attach Thermax sheathing with a radiant barrier to the studs over the batts and seal the seams. Sometimes the construction, access, and penetrations make using a rigid foam board product very difficult to use. The bubble wrap radiant barrier seems to be a good alternative.

Installed in that location -- over the fiberglass batts -- I would be concerned about condensation on the bottom surface wicking into the fiberglass and creating mold habitat.  I'd also be concerned that dust would accumulate on the top surface and make the radiant properties useless. 

Has this stuff been in use long enough to be able to check in on an installation that's 5 or 10 years old to see how it's holding up?

Jon,

 

  I'm guessing that the foil/bubble wrap will provide a real good air seal if installed properly (like every other air seal material) but will be much more costly than poly wrap and not provide anywhere near the insulation of EPS or XPS board.  I've seen no independent testing of these products to verify their claimed "R" values.  Knee walls are always a pain; almost makes you want to rip out the walls to re-do everything.

You can say that again.
We see Reflectix used behind knee walls all the time.  It is the air barrier to prevent windwashing, and meets code for fiberglass batt covering.

You should put a link to Reflectix in your post. I haven't heard of it.

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