Bubble/foil insulation

Thanks for the reference. I still have customers ask about it, and it's good to have somewhere to point them. That stuff does make nice toasty hats though......

I used some around my 80 gallon hot water heater, over a layer of fiberglass. Didn't know what else to use to hold the glass up, & it has that neat shiney spacey look.

Think I also still have some in place around some of my pipes, again to hold a layer of fiberglass in place - that was before I found some real pipe insulation here.

The link isn't opening for me. Aren't air bubbles good for insulation? However, I agree the moderate temperatures and unpredictable surface conditions lead me to not believe that a foil finish will help much with radiative heat transfer.

I'm curious because I am getting ready to run about 40 feet of 12" round duct through my unheated garage (20' hot supply, 20' cold return). I'd appreciate any suggestions.

Can't get link to open???

The link still wouldn't open for me now, although I was able to find a cached page without pictures.

Long page, I skimmed it, it seemed to debunk the reflective aspect, which makes good sense to me. I was mainly curious about why the air bubbles don't help, though.

Since then, I see my Wisconsin-based big box store's website has an "insulated duct sleeve" rated at R6. Says it has a fiberglass core with a tear-resistant vapor barrier. Is this the kind of thing the learned people on hearth.com use? Not available in the store for inspection, internet order only. I can't say I've paid attention to duct insulation before so I don't know what I'm looking for or if there are numerous good options.

Karl_northwind said:

Thanks for the reference. I still have customers ask about it, and it's good to have somewhere to point them. That stuff does make nice toasty hats though......

Click to expand...

Pretty good boot insole's also, until you pop all the bubbles

1.1 r-value, it has it uses...take for instant, if u were lost and had a piece u could reflect with it to a passing plane . or check out the ONLY "building use".... for the stuff in my post below...

It is a product looking for a use. Unfortunately, most people see the shiny part and think reflectivity connotes high insulation value.
It does make cool looking packing material, though.

This reminds me of back in the day I'd see people wrap their soda cans in aluminum foil to try to keep them cool longer. That's gotta perform even worse than bubble wrap for sure. And there was no talking them out of it, "of course it keeps the cans cool longer, that's what my mother/father/teacher/etc. has always told me..."

I did staple the stuff to the bottom of my "I" joist flange (16" BCI's - under warmboard) which in turn left the 1.75" space of reflective space, rolled the end of it back on itself & and I spray foamed the ends of the joist bay at the rim board = dead air space..... I put a layer of fiberglass up against the foil (from the bottom) makes for quite floor and warm feet ...8" walls and the foil stops 3" inside the building envelope!

I have that stuff around my two vertical storage tanks, again to hold up the fiberglass(r-38 or better) so that seems to be the only good purpose for the stuff. It has to reflect some heat right?

It will reflect some heat and is a decent barrier for covering fiberglass. As a solo insulation product, it is not very good.
If I was going to insulate a tank with fiberglass, I would use 4' wide rolls that are available at most lumber yards. They are covered with plastic and are an all in one package that are less expensive.
The radiant barrier is not really necessary with some bulk insulation there. Heat is not going to radiate through 4+" of fiberglass very well.
I think these wide batts use a plastic that has a reflective component to them, even though they are usually white on the outside.