Any Experience with Radiant Barrier Bubble Wrap

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Permalink Reply by Ben Stallings on February 8, 2011 at 6:34am

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.

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Permalink Reply by Jon LaMonte on February 8, 2011 at 7:58am

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.

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Permalink Reply by Ben Stallings on February 11, 2011 at 7:18am

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?

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Permalink Reply by David Eakin on February 10, 2011 at 3:31pm

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.

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Permalink Reply by Jon LaMonte on February 10, 2011 at 3:35pm

You can say that again.

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Permalink Reply by A. Tamasin Sterner on February 10, 2011 at 7:35pm

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.

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Permalink Reply by Guy DuBois on February 13, 2011 at 8:51am

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

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