Comments on: Is Compressed Fiberglass Insulation Really So Bad?

By: Jordan Block

Jordan Block — Wed, 16 Sep 2020 02:56:13 +0000

I currently have a space
I currently have a space approximately 4.5” deep that I am looking to fill with R-19 and also have a space 4” deep that I am looking to fill with R-15. There may be a small gap in the 4” area that I am looking to fill with R-15 with need for increased compression on the wall with the 4.5” space (compression of approximately 1.5”). Is this the best plan of action or are there any suggestions in the types of insulation (R-15/R-19) I am looking to use?

By: Jinsung Wang

Jinsung Wang — Fri, 17 Jul 2020 03:54:26 +0000

Hi,
Hi,
Thanks so much for this article. I have a question for you regarding what you wrote: “you can compress fiberglass insulation as much as you want.” I am trying to make a shower niche on a 2×6 exterior wall, in which fiberglass insulation already exists. I believe it is R-19. To make a niche, I want to compress the insulation quite a bit, down to only 1.5 or 1.75 inches. What R value or R value per inch would this give? Is it ok to compress it this much, assuming it will fill the cavity completely? Or, will it be better to remove the fiberglass insulation and replace it with 1.5 inch polystyrene insulation board with the R value of 7.5? By the way, behind the fiberglass on my exterior wall, I see some type of form board (don’t know how thick it is). So, I don’t know if it’s a good idea to put a 1.5 inch form board on top of another form board. Any comments from you would be greatly appreciated!!!

By: Funkymut

Funkymut — Fri, 03 Jul 2020 01:13:07 +0000

NEED ADVICE ANYONE? I
NEED ADVICE ANYONE? I contract a company that makes trailers for me. The walls have only 1 inch space for me to work with. I want to make sure my customers I sell to that are from the colder regions like MN or MI are comfortable. I want at least R-13 (at least that's what someone told me). So what would you (anybody) recommend I do? Thanks for any input.

By: Victoria Boyd

Victoria Boyd — Thu, 31 Oct 2019 20:31:04 +0000

I’m fighting a really weird
I’m fighting a really weird old house situation.
The 6″ deep rafters were left completely uninsulated, with the long roofing nails uncut on the inside. When the attic was turned into a living space, they put the old thick, real wood beadboard over them. Now I’m trying to figure a way to squeeze insulation into that space. No one does poured foam in my area… and the cost is prohibitive in general right now.
If I could find a way to wrap fiberglass batts in something and vacuum them down flat, them slide them into the space, and let the air back in, would they decompress and fill the space around the nails and give me at least 6″ worth of insulation behind the beadboard? Would blown in cellulose go around the nails to fill it up?

By: Billy Morris

Billy Morris — Sun, 24 Mar 2019 20:24:18 +0000

In reply to abailes. Seen this post on insulation.
Seen this post on insulation. Dont know a lot about it. My friend hastorn of all the old paneling of the walls of her old trailer and i think the studs are like maybe 2x2 and practically no insulation can she use regular builders house insulation. I've been told u can't compres it. But it has to be better than nothing? Any help would be appreciated. Tks

By: Ronald Hillberg

Ronald Hillberg — Thu, 14 Mar 2019 16:01:55 +0000

Good to know. I want to stand
Good to know. I want to stand off a facade from basement foundation and now I know I can oversize the insulation so it fills in behind the studs and cuts drafts and thermal breaks. I just have to make sure I don't get condensation! I have seen a lot of unfaced bats that are not very regular and it's good to know to err on the side of putting a little more in.

By: Charlie Cain

Charlie Cain — Mon, 04 Feb 2019 15:48:11 +0000

Is this the same with normal
Is this the same with normal ‘fluffy’ insulation rolls? I am currently insulating my loft and have used RWA45 100mm bats (I got for free) for the lower layer, and 100mm standard rolls for the 2nd layer as I have 200mm to insulate before the loft boards.
The roof is low pitch, so I didn’t want to go to 270mm.
I have lots of the insulation roll left over which I can’t return.
Would I be better adding more insulation into the gaps to pack it tighter and compress it down? I’m not fussed about wasting insulation as I can no longer return it, but presumably that would give me an overall better R Value. Everything else I’ve read so far says no, but this article says yes from my understanding.

By: captbatn

captbatn — Fri, 08 Jun 2018 21:27:10 +0000

In reply to Paul. It is the air that insulates
It is the air that insulates in conduction mode, but the fiber is there to limit convection of that air as convection has the potential to move much more heat, higher density better limits convection. It is a case of diminishing returns however as the pure glass is more conductive than the air and convection is already quite slow in normal open cell batts. 3.5 inch r-11 has a density of around .55, r-13 is made .75 and r15 is 1.45 pounds per cubic foot. R-15 insulates like a 4.75"(136% of 3.5") wall filled with .55 density material, but uses 260% of the material.(same mass of glass could fill 9.1 inches at .55 density which is r28, but of course that requires more wood) (alternately closed cell foam like styrofoam has no convection as such any compression is bad)

By: Allen Linoski

Allen Linoski — Tue, 17 Apr 2018 17:26:21 +0000

In reply to Cosette. For the sloped ceiling areas,
For the sloped ceiling areas, install rigid board insulation under the drywall. I went with 1" XPS. Just remember to buy longer drywall screws.

By: Pat Huelman

Pat Huelman — Tue, 11 Jul 2017 17:01:02 +0000

In reply to Pat Huelman. See ASHRAE HoF (2013) Chapter
See ASHRAE HoF (2013) Chapter 26. Figures 1 and 2. Chapter 25 does a nice job on fundamentals including air spaces that can come in handy, too.