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Problems installing cotton insulation

Posted June 05, 2008 11:05 AM by Tristan Roberts
Related Categories: Product Talk
I bought some Ultratouch cotton fiber insulation a few months ago thinking that it would be a great natural product for the cabin I am building. This is the stuff that comes in blue unfaced batts, and is often said to use recycled blue jeans, although it uses pre-consumer denim from factory waste. I bought it from a (great) Brattleboro, Vermont retailer Renew Building Materials and Salvage for for 88 cents a square foot. Unfortunately they ship it from Arizona but it seemed worth the effort. Within a couple hours of working with it, however, I was ready to abandon it in favor of blown-in cellulose, and returned all of the unopened bags minus a restocking fee. What went wrong? Three things.
  • It's too thin
  • It's too wide
  • It's hard to cut
The worst flaw of the product is that it is too thin. I bought the R-13 batts that are supposed to be 3.5 inches thick to fill the stud cavities in a standard 2x4 stick-frame wall. Just like the fiberglass insulation I've worked with in the past, the batts were compressed into a bag for shipping. You are supposed to be able to take them out of the package and they will "fluff up" to full size in a process called "loft rebound." However, as the photo above shows, that never happened. The actual thickness varies. At best it's three inches; at worst it's less than two. This photo, by the way, is taken after the batt has been sitting out, uncompressed, for six full months. It did all of its "fluffing" in the first few hours and hasn't improved since. What's wrong with that if it's R-13? Well, it's not really R-13. The air pockets provide the insulation, not the cotton. If you take the same cotton and compress it into a smaller space, there are fewer air pockets and thus less R-value, as the cotton conducts more heat. That R-13 value is based on 3.5 inches of fluffy cotton with lots of airspaces, not two inches. Also, since the batts are so thin, they leave about half the stud cavity open. That massive air cavity (which remember, I already paid 88 cents per square foot to fill) provides ample room for air currents to move, sucking out heat and bringing in cold air, worsening the total R-value of the wall even further. The people I bought it from at Renew were concerned. They noted that the larger R-19 batts seemed to fluff up better. They encouraged me to give my feedback to Ultratouch. When I asked the Ultratouch reps about this problem they told me that they haven't had such problems. Secondly, it's too wide. According to Bonded Logic, the makers of Ultratouch, this is a feature, not a bug. To quote the website: "UltraTouch is manufactured in oversized widths to ensure a tight friction fit and fill capacity." Indeed, the insulation I bought is a full 16 inches wide. Meanwhile, the standard 16-inch on-center stick-frame wall that I had built has a stud cavity that is 14.5 inches wide. So a full 1.5 inches of the stuff is added on for a "friction fit." I wasn't expecting this when I opened the package, but I was willing to give it a try. In practice, I would say that a 1/4-inch of extra width would be enough to provide the friction fit. So what happens to the additional inch-and-a-quarter? It gets squeezed into the corners. You then have two problems. One is that the batt balloons out a little to the front, creating a significant airspace behind it. Two is that the insulation on the edges gets compressed, reducing its R-value. That also rounds the corners of the insulation, and since the stud cavity is rectangular, not rounded, it adds air gaps running all the way up and down, creating convection and further reducing thermal performance. You can see both effects taking place in this photo: Again, Bonded Logic insist that this is not a problem. At Greenbuild last year, the reps told me that it worked for them when they installed it. Curious, I came back to their booth at the recent AIA National Convention in Boston to research the issue further. The Ultratouch booth features a gorgeous stick-frame wall with batts of Ultratouch installed, looking perfect and also, strangely unattainable. So how'd they do it? Using a tape measure from the Lafarge booth down the row (thanks!), I measured the wall and found that the official Ultratouch mockup uses 17-inch on-center construction. This allows an extra inch to accommodate the wide batts. Wacky! But clearly these guys knew what they were doing. My question is--why haven't they told the rest of us? Knowing what I know now, if I were to use this product again, I would either use a nonstandard framing technique such as 17-inch-o.c. walls like Ultratouch did, or I would rip every single piece lengthwise to attain a more exact fit. But -- and this offers a good segue into my third point -- the stuff is really hard to cut. Treating it like fiberglass, foam, or many other types of insulation that can be cut with a utility knife will give you a shredded, uneven end -- see the lower end in the photo. (Tearing it by hand, as Peter Yost and Nadav Malin here at Environmental Building News found they had to do when they reviewed the product eight years ago, works somewhat better, although it generates a lot of dust. Peter also noted the same problem with loft rebound in that article. It would be great to to into his attic to check on that now.) Bonded Logic recommends the Insul-Knife made by Cepco Tool Company to cut it instead. I acquired one of these and found that it's a really nifty tool that has all kinds of uses. Cutting cotton batts is not one of them. It does create a satisfactory cut when it's really sharp -- see the upper end in the photo (above). But it requires a lot of elbow grease, and it dulls within a few cuts and requires sharpening. Also, it works best on crosscuts, and is not very practical when it comes to getting a long, straight rip. Bonded Logic recognizes this, apparently, because they also recommend a Bosch Foam Rubber Cutter as a motorized cutter. I wasn't that interested in buying a specialized power tool just for installing insulation. If I were doing a large commercial job, however, I imagine that this would work well and probably wouldn't take much longer than cutting fiberglass, at least until you factor in the ripping. For the several pieces that I did install, I found that a tablesaw worked best for long cuts, and a circular saw worked reasonably well for crosscuts. I have talked to other residential installers and found that people who stick with the product find a motorized system that works for them using standard tools. I might have done so if not for the product being too thin. As I stood there in my freezing cabin last winter (which wasn't getting warmer very quickly with the problems I was having with Ultratouch), I thought about setting up a motorized cutting system with tools on hand, and ripping every single piece. But I realized that I could do all that and still not get the thermal performance that I had paid for because of the lack of "fluff." I was already planning to blow cellulose into the ceiling so I decided to do the walls as well. Have you installed cotton insulation? How did it work for you? I do have some good news to report from my search for the ideal way to cut Ultratouch. I came across the Olfa 45-mm rotary cutter. While this didn't work for Ultratouch, I love using it on materials like burlap, housewrap, and red-rosin paper--provided that I am cutting on top of a hard surface. Because it rolls and avoids thus avoids catching on things, it works much better than a utility knife in some applications. Replacement blades are spendy, though.

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Comments

1 I found out that 16" insulati posted by Mike on 10/22/2008 at 09:17 pm

I found out that 16" insulation is needed when you use metal framing. This allows it to be friction fit into the cavity (which is 15 7/8") when the studs are 16" on center. The reason for the extra space in the cavity is because of c-channel design of the framing adds almost an extra 1 1/2" to the cavity.

2 hey i think you need to try m posted by the phoenix on 05/17/2011 at 10:21 pm

hey i think you need to try mr. insulate< he is the most updated and earth friendly cotton product out there, less dust easy tear, no gloves or mask or stapler gun no long sleeves but most of all no fiberglass to hurt ur babies if they wonder in the room while your installing it

3 I am still installing Ultra T posted by Rob Hickey on 05/17/2009 at 07:07 am

I am still installing Ultra Touch Cotton Fiber into the interior walls of a new house, mostly for sound control. I have not had as much of a problem with how the batts fit in a standard cavity but it is much easier when you can work it in from both sides. I found the rebound loft to be very impressive, as good if not better then fiberglass. Cutting this product however, is so difficult, I would never recommend it on a large job that needed to get done fast. It is exactly as though you were trying to cut through jeans that are over an inch thick and 8' long. If you said that to a seamstress you would probably see tears well up in her eyes. The only way to actually cut this stuff is a pair of 12" tin shears. It's slow and you will get blisters, but you can cut it straight and make it look like the demo at the convention.

4 As examined carefully by Buil posted by Andrew on 06/03/2008 at 09:38 am

As examined carefully by Building Green, there are tradeoffs with all types of insulation. I installed UltraTouch insulation throughout my house during a full renovation and I can attest to the problems that the blogger documented, yet I thought many of them were due to the wacky framing in my house. The size problems are a valid concern and should be promptly addressed by Bonded Logic. The drop in R-value by missized insulation takes away from the indoor air quality and recycled content advantages that you gain from using the insulation. That being said, the cutting of the insulation wasn't a large problem for me. If you have a sharp knife (shown in picture) and a sharpener (both were provided free from my supplier) then it takes only slightly more effort than standard fiberglass insulation. Plus, its easy to rip around for obstructions. One thing that is not adequately explained from the manufacturer is that, if you are installing a large amount of this insulation, you should still wear a facemask for comfort and health. Handling a large amount of the material generates a fair amount of the "blue" dust that can become quite irritating after prolonged exposure. After installation, I was covered from head to toe (especially my arms) in a nice coating of blue jean dust. Wear a mask, its worth it.

5 architecture student here, wi posted by john blank on 11/07/2008 at 02:53 pm

architecture student here, with many years experience of building... so, the complaint here is two-fold: too wide and too thin. If I were building a "cabin," and by that I assume you're implying it will be built in some kind of hostile environment, I would immediately recommend upping the insulation from R-13 to at least R-19 for better results. I myself am in the market for denim batt insulation, for a small building in an unforgiving environment and I have come across denim rolls with even R-30 value. As far as being too wide, I would much rather have a batt that was an inch wider, than one that would fit 16"o.c. but might have small gaps between it and the studs. I would personally rather have to "squish" the batt in than have to "stretch" it. Good luck.

6 I thought the wider batt was posted by Stefan on 08/04/2008 at 07:29 am

I thought the wider batt was helpful. I just installed UltraTouch into a vaulted ceiling cavity. I applied the R-19 batts over 2 inches over spray foam and found that the wider batt allowed me to pin to sides of the 6 inch rafters instead of trying to go through the foam.

7 The one criticism which may n posted by Robert Riversong on 06/14/2011 at 01:35 pm

The one criticism which may not be accurate is the assumption that R-value decreases with increased density. It's always true that overall R-value will diminish when a batt is compressed, but most often the R/inch increases with additional density - contrary to what intuition might suggest. Why is foam such a high-R insulator? Because the air pockets are microscopic. Fiberglass batts rise considerably in R/inch with increased density, as the industry discovered when they shifted from low-density R-11 3½" batts to medium-density R-13 3½" batts (which is basically an R-19 batt compressed to 3½"). The semi-rigid fiberglass foundation drainboard has as much as R-4.3/inch because of its high density.

8 This is a fabulously written posted by shawn on 04/26/2009 at 05:58 pm

This is a fabulously written article. Thank you for taking the time to offer a balanced - if critical - assessment of your experience with cotton batting. The photographs and accompanying textual explanation are hilarious. In addition to learning your story you had my wife and I laughing. Well done and thanks again.

9 I am installing batts in a ne posted by Don on 06/12/2009 at 10:06 am

I am installing batts in a new construction. I also had difficulty cutting the product. However, I then tried my skill saw with a mason blade and it works like cutting butter. It is great and has saved me much time. I highly recommend it. I also tried a metal cutting blade and that works gre4at as well. Putting these blase on a table saw makes width cutting very easy.


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