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Old 10-31-2019, 03:59 PM   #1
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Pink stuff for roof insulation

I don't see many threads about using the pink stuff. I got a very good price on it and plan to cover it with t&g. I'll seal the seams then stain. It loses thickness but gains insulation per inch when compressed. In a test area, we were able to maintain a 60 degree difference between indoor and outdoor temp at the ceiling.

Any reasons why not to do this?

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Old 10-31-2019, 04:52 PM   #2
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Pink stuff? I assume you mean the pink fiberglass insulation used in homes? I used three inch, compressed to 2" in my bus. Not by any means saying that is the best idea, it is just what I did.

3" is normally 13 "R" value. So do you mean 13 R would be more if compressed? I thought it lost some when compressed.
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Old 10-31-2019, 05:00 PM   #3
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This is 9", compressed to about 3". My busmate did the research on R values and I don't know the details. Just that it's a hell of a lot more comfortable in that area than the areas that don't have it. The original stuff we pulled out is 1" thick and looks like what you might find in an old sofa.
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Old 10-31-2019, 05:12 PM   #4
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Compressing fiberglass insulation reduces its insulating properties, such that there is no point to compressing it - in other words, 9" of fiberglass insulation compressed into a 3" thickness will not have an R-value better than 3" of uncompressed insulation (and it will likely be even worse).

In general, insulation (of whatever kind) works because it traps tiny pockets of air; over-compressing insulation ruins this.
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Old 10-31-2019, 05:17 PM   #5
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I just found a chart online and musigenesis is right, thicker compressed to 3" is about the same as 3" not compressed. My 3" compressed to 2" (because it is what is readily available) comes out to about 9 "R" value.
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Old 10-31-2019, 05:25 PM   #6
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Thank you for the info. I will consider adding more insulation on the outside if needed.

I am still interested to know why people do not seem to commonly use this stuff.
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Old 10-31-2019, 05:46 PM   #7
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Condensation. A bus doesn’t breathe the same as a house. The only way I see that it could work is if were fully encapsulated in plastic film. They sell stuff like that. If you use it seal the cut ends.
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Old 10-31-2019, 05:46 PM   #8
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Thank you for the info. I will consider adding more insulation on the outside if needed.

I am still interested to know why people do not seem to commonly use this stuff.
It's about R-3 per inch vs. R-4 or R-5 per inch for EPS or XPS foam board. When head room is tight, you really can't get away with fiberglass.
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Old 11-03-2019, 02:18 AM   #9
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Besides, the loose fiberglass is itchy to install and plays havoc on your lungs if inhaled ... and you can believe there WILL be fiberglass dust generated in the installation.
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Old 11-03-2019, 02:53 AM   #10
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Thank you for the info. I will consider adding more insulation on the outside if needed.

I am still interested to know why people do not seem to commonly use this stuff.
cause eventually it can get nasty. It can grow mold. You get much better service from closed cell foam products so most folks use those.
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Old 11-03-2019, 06:03 AM   #11
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cause eventually it can get nasty. It can grow mold. You get much better service from closed cell foam products so most folks use those.
It's weird, you've seen how rusted my bus is, but every piece of fiberglass insulation looked brand-new from the factory, not a hint of mold. I wonder if the mold is more common in slightly-leaking buses where a tiny bit of water gets in and sticks around, vs. buses like mine that quickly become self-draining.
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Old 11-03-2019, 06:27 AM   #12
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Non of the insulation was moldy in my bus. The walls were rather skimpy, so replaced all the wall insulation. The new fiberglass does not itch. Oh the old stuff itchy.... I remember doing an attic in the summer once. That was just awful.
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Old 11-03-2019, 08:47 PM   #13
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Non of the insulation was moldy in my bus. The walls were rather skimpy, so replaced all the wall insulation. The new fiberglass does not itch. Oh the old stuff itchy.... I remember doing an attic in the summer once. That was just awful.
Good to know the new stuff does not itch.
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Old 11-17-2019, 12:09 AM   #14
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Foil bubble foil gets you a great r value. Easy to work with and you canDouble it up.
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