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Fiberglass and Cellulose Makers Tangle Again

Online articles reignite a long-standing dispute between competing industries

Cellulose insulation makers are crying foul. Articles referencing a 2016 advertising industry case has a trade group representing cellulose makers up in arms.
Image Credit: Forgemind / CC by 2.0 / Flickr

A long-running feud between the fiberglass and cellulose insulation industries has broken out in a new round of mudslinging, drawing a public rebuke from an agency that oversees truth and accuracy in advertising.

The latest spat started with the publication of three online articles that challenge the performance claims for cellulose while suggesting that the insulation, made mostly from newspaper, is a potential fire and safety hazard.

The articles, which appeared in March and April, prompted a statement from the Advertising Self Regulatory Council (ASRC) in early May chastising fiberglass insulation manufacturers for breaking advertising industry rules.

The dispute hinges on a case brought before the National Advertising Division, a part of the ASRC, last year in which the North American Insulation Manufacturers’ Association (NAIMA), a trade group representing fiberglass insulation makers, challenged claims by Applegate, a Michigan-based cellulose manufacturer. But it goes much deeper than that, and the most recent round of bickering underscores the depth of the divide between these two industries and has a lot to say about how a public relations war can be waged.

The original complaint

NAIMA took its beef with Applegate before the National Advertising Division last year. It objected to a number of claims that Applegate made about cellulose: that it could reduce energy bills by as much as 40%; that it’s better at sound suppression than fiberglass; that its fire retardant additive is non-toxic; and that its R-value per inch was nearly twice that of fiberglass.

Applegate based its advertising claims on three studies, but NAIMA complained that the data were incomplete, misleading, and out of date.

“It was the challenger’s position that none of these reasonably support Applegate’s claims because they are outdated, limited in scope, fail to disclose information necessary to assess their reliability, and did not address fiber glass insulation products currently on the market,” a NAD document on the case says.

One of the studies, for example, was more than 25 years old, NAIMA pointed out. It compared air leakage in a building insulated with cellulose to one insulated with fiberglass batts. The buildings were rooms, really — 8 feet square — at the University of Colorado. A second study was conducted by the Housing Authority of the City of Leominster, Massachusetts, on a single building in 1986 and showed, according to Applegate, that cellulose provided 32% energy savings over buildings insulated with fiberglass. The third study came from the Oak Ridge National Laboratory in the 1990s and looked at the loss of R-value in extremely cold temperatures.

NAIMA attacked the studies on a number of fronts, claiming that “Applegate systematically fails to inform consumers which products it is comparing in its advertisements… any of Applegate’s unqualified and general claims that Applegate’s (or any other) cellulose performs better than fiber must be supported by comprehensive side-by-side testing of its specific Applegate Cellulose Insulation formulations versus each and every type of fiberglass insulation on the market today,” the NAD document says. “Applegate’s reliance on three, irrelevant and outdated tests suggest that no such testing or data exists.”

The safety of borate fire retardants in cellulose was another issue. NAIMA pointed to claims by Applegate that “some studies have shown boron might lower the risk of some cancers and is a chemical commonly found in vegetables, such as almonds, apples… and pears.” Applegate claimed that the fire retardant is six times less toxic than table salt, NAIMA said, when in fact the Occupational Safety and Health Administration lists boric acid as a hazardous substance.

NAIMA also claimed that Applegate’s R-value claims about cellulose violated Federal Trade Commission regulations.

In short, NAIMA’s filing was another broadside against a rival in a fight that dates back at least two decades.

Applegate replies

Applegate, of course, didn’t agree with much of anything that NAIMA had to say. It called the studies it relied on credible, even though they were decades old.

“The advertiser rejected NAIMA’s characterization of these studies as ‘outdated,’ noting that the fact that information may be 25-30 years old does not invalidate it,” the NAD case summary says. Further, while Applegate acknowledged the fiberglass industry has introduced new products since the studies were conducted, they may not be any better than the old stuff.

“These products may or may not offer thermal performance equivalent to cellulose, and NAIMA offers no evidence that they do,” Applegate claimed.

The company added that numerous blower door tests showed “significant reductions” in air leakage in cellulose-insulated houses compared with uninsulated or fiberglass-insulated houses; and it cited a Building Science Corporation report showing a 50% reduction in air flow for cellulose over two brands of fiberglass.

Applegate also said that numerous reports “from the real world of buildings” showed cellulose is a better thermal insulator than fiberglass, including a study of a Pennsylvania tract development where cellulose-insulated homes used 34% less energy for heating with heat pumps and 26.6% less with “baseboard heating” compared to houses insulated with fiberglass.

Down the list Applegate went, rebutting each of NAIMA’s complaints with assertions and citations of its own. It’s message: Back off, we’re on firm ground here.

What NAD decided

After looking at both NAIMA’s original complaint and Applegate’s responses, NAD made a number of suggestions.

(1) Applegate’s “unqualified nationwide superior energy savings performance claims must be supported with reliable evidence that consumers in any region can actually achieve the touted energy savings and consequent reduction in the amount of their utility bills.”

(2) Applegate’s products were not used in any of the three tests it cited, nor were any type of fiberglass insulation other than batts. Fiberglass available today is not the same as it was when those tests were conducted, and the tests are of limited scope. “NAD determined that the results of the Colorado study, the Leominster, Massachusetts study, and the Oak Ridge Study do not reflect the real world conditions under which fiberglass would be installed today… NAD recommended that these claims be discontinued.”

(3) Applegate should stop claiming that some studies show boron (used in the fire retardant) “might lower the risk of some cancers.” Further, reports from two federal agencies “do not support a finding that borates are ‘non-toxic.’” NAD suggested that Applegate stop claiming that fire retardant additives are non-toxic and that boric acid is “six times less toxic to humans than table salt.” NAD added that Applegate shouldn’t be prevented from making “an appropriately qualified claim” about the safety of its product.

(4) Applegate did not violate FTC’s R-value-per-inch rule.

(5) NAD recommended that Applegate should drop claims that its insulation “quiets a home better than fiberglass,” and that it should stop using its “sound bucket” demonstration in future advertising.

The decision seemed largely in favor of the fiberglass industry, and Applegate pledged to take NAD recommendations into account, even if it disagreed with some of the findings.

“NAD has apparently been misled to believe fiberglass companies have developed higher design density loose fill products specifically for cold climates, while just the opposite is true,” Applegate said. “However, out of respect to NAD and the inability to allocate the resources to appeal (our total sales don’t even come close to equaling the marketing and advertising budgets of NAIMA’s members), we will take the NAD’s recommendations into account for current and future advertising materials.”

Another jab from fiberglass

That should have been the end of it, but NAIMA couldn’t stop itself from taking one more poke at the cellulose industry. Well, actually three more pokes. They arrived in the form of articles posted at three different websites: a post by John Burnett at the Huffington Post; a post by Erin Mundahl at Inside Sources; and one by Peter Roff at RealClear.

None of the authors appears to have any particular expertise or interest in construction issues. For example, John Burnett’s bio at Huffpost describes him as a “financial services executive,” and “urban financial freedom fighter, and a Republican strategist.” Roff is identified as a contributing editor at U.S. News & World Report who writes about politics. (“Congressional Republicans Need to Stick by Donald Trump During Media Attack” was one of his recent articles.) The article at Real Clear was apparently his first post at that website. Mundahl has a long list of writing credits at InsideSources on a variety of topics. While she has written a number of articles about energy policy, none of the stories listed at the website concern the building industry other than her April 7 article about insulation.

All three of the blogs referenced the NAD findings, and that was the problem — using NAD findings for promotional purposes is against the rules. The ASRC subsequently issued a statement making clear that “parties to an NAD case are prohibited from using NAD decisions for promotional purposes.” The statement continued: “A public relations company working on behalf of NAIMA commissioned articles in three separate publications that used the NAD decision to promote fiberglass insulation.”

In a telephone call, Linda Bean, director of communications for the ASRC, would not identify the PR firm and referred that question to NAIMA. She did, however, say she was surprised to see the blogs nearly a year after the original NAD decision was issued.

“The three articles in quick succession in very diverse publications, all written by people who did not appear to have connection to the insulation industry, did make us ask what is going on here,” she said. “So we did go back to the advertiser [NAIMA] and say you may not use the decision for promotional purposes. We’re seeing some stories about this. Do you know where they’re coming from? The advertiser did some searching and determined that there was a PR agency that was working on their behalf but not necessarily under their direction that had figured out a way to get a little more attention around this and had farmed out some stories.”

NAIMA, in turn, apologized for the lapse and promised it wouldn’t happen again, Bean said.

GBA attempted to contact each of the three authors to find out why they chose to write about insulation, particularly now, and what talking points, if any, were provided by the PR agency working for NAIMA. Neither they nor representatives from NAIMA returned calls.

However, an article posted at Canadian Contractor said that a NAIMA spokesman initially denied NAD’s claims but later said, “Maybe I’ll have to discuss that internally. Maybe we need to clean up the language to make that a little more clear, but [NAIMA’s denial] is what we want to convey.”

Participation is voluntary

Bean said that there should have been no confusion about what is permitted under industry rules.

“Sometimes companies are very surprised when I call and say you can’t do that,” she said. “The rules are pretty clear… What is also often the case is the legal department in a particular company absolutely understands exactly what the participation agreement looked like because they are the ones who signed it. But word never made it down to the marketing intern who read about the decision somewhere and thought that made a great post for the company’s blog. It’s the part where the information doesn’t cycle fully through the information ecosystem. It’s not that anybody set out to do something wrong.”

Bean added that the self-regulatory nature of the process means that participating companies give up some privacy along the way.

“Self-regulation is a voluntary process,” she said. “It requires the parties that come here to let us finger our way through all kinds of confidential information. So they come here voluntarily knowing we are going to poke around and ask questions. It can feel uncomfortable. But because they have some sort of commitment to truth and accuracy in the marketplace, they do it anyway. And so even companies that get an adverse decision, you have to appreciate the fact they to that voluntary. That says good things about a company even if the decision isn’t the one they wanted. I think that’s a good thing. We never look at these as bad guys.”

Cellulose trade group fires back

In a lengthy rebuttal titled “Fake News!” Lea took aim at the posted articles as well as the NAD recommendations to Applegate about its advertising.

“A suspicious person might conclude there is a planned and coordinated competitive campaign against cellulose insulation underway,” Lea wrote. “That turns out to be the case. These largely false and misleading items were ‘planted’ by DCI, a Washington, D.C., public relations firm.”

Lea said that the recent articles were reminiscent of a campaign to discredit cellulose in the 1990s organized by NAIMA, involving CertainTeed, Owens Corning, and Johns Manville, all members of a “Cellulose Committee tasked with eliminating cellulose as a serious competitor to their products.” He said that the companies were behind ads, videos, a white paper aimed at discrediting cellulose, as well as attempts to influence code-writing organizations.

He revisited the NAD proceedings to defend some of Applegate’s advertising claims, and added: “Not content to stick with basing their attacks on NAD’s report, Burnett, Mundahl, and Roff,

apparently following a script provided by to them, proceed into areas not mentioned by NAD — fire

safety, for instance.”

Lea was particularly critical of Burnett’s article, “Cellulose Insulation: Is it Lumber Liquidators 2.0?” an apparent reference to allegations that flooring sold by the firm contained hazardous amounts of formaldehyde.

“Burnett’s introduction of Lumber Liquidators is unconscionable. Cellulose insulation has been used in

large amounts for nearly 70 years. During those seven decades the only health hazard allegations have come from manufacturers of a competitive product that apparently can’t be sold on its own merits, not from credible authorities. Cellulose insulation and its components have never been cited as probable or even possible carcinogens. Fiber glass, on the other hand, has been classified by the National Toxicology Program and IARC as a probable human carcinogen. After years of lobbying by fiber glass interests this was changed to insufficient data to classify – hardly the total whitewash fiber glass manufacturers represent it to be. Fiber glass was once identified in a Cornell University study as a possible cause of sick building syndrome.”

GBA placed a call to DCI in Washington and will update this report if the firm responds.


  1. GBA Editor
    Martin Holladay | | #1

    What's going on at NAIMA?
    It sounds like NAIMA lacks adult supervision. The big players like Owens Corning, CertainTeed, and Johns Manville need to step in -- these cowboy-style attacks from their trade group aren't burnishing the images of otherwise responsible insulation manufacturers.

  2. JC72 | | #2

    @Martin. Agree. I waiting to hear NAIMA claim
    that they employ far more people than the cellulose industry and their jobs are "at stake".

  3. demouser | | #3

    One issue with cellulose is that rodents love it for nesting. They will even chew through sheathing to get in. Once inside they can build networks of tunnels inside walls.

  4. GBA Editor
    Martin Holladay | | #4

    Response to Horst Fiedler
    Actually, Horst -- at least in my experience -- you have the situation exactly backwards.

    I can't tell you how many times I've pulled apart walls (or renovated an attic) and come across mouse droppings or mouse nests (often with hoarded food) in the fiberglass batts.

    I've never seen that with cellulose. Many builders theorize that the boron in the cellulose inhibits mice. I don't know if it's true, but in my experience, if you want to discourage mice, get the cellulose, not fiberglass.

  5. shtrum2 | | #5

    weatherization and cellulose
    The national DOE/Weatherization Assistance Program (WAP) only uses fiberglass batts in limited situations (e.g., in floor joists). And loose-fill fiberglass is used in wet conditions, such as mobile home belly insulation, or in situations where there's contact with metal (to counteract concerns that the boric acid fire retardant in cellulose might cause issues). But the standard has always been to blow cellulose in walls and attics; it’s a little cheaper and lighter than loose-fill fiberglass. And both options show appreciable blower-door reductions.

    I’ve never heard of rodents being an issue with cellulose, although there’s certainly critter issues when working in any attic or crawlspace. The biggest concern with blown-in insulation is whether it can be used with existing knob and tube wiring. The jury is out whether it’s a fire issue . . . we don’t allow it (as a matter of safety) but other programs use it, at least in loose-fill applications. But the fire concerns apply for either material.

  6. Expert Member
    Dana Dorsett | | #6

    The fire retardents are generally eye irritants @ Martin #4
    My experience has also been that fiberglass batts all too often become mouse nests, and cellulose generally does not. It may be the eye irritant factor, since rodents don't seem to have any problem using untreated newsprint for nesting materials.

    I had a squirrel chew into a bag of all-borate cellulose stored in the garage once, removing perhaps a fist sized amount and making a mess, but he didn't nest in or with it. (He chewed through 1x plank sheathing and set up house in a wall cavity instead.) That's the only time I've witnessed rodent-disturbed cellulose first hand. But I've seen any number of fiberglass batts reeking of eau d' rodenia.

    Patrick: "But the standard has always been to blow cellulose in walls and attics; it’s a little cheaper and lighter than loose-fill fiberglass."

    Cheaper perhaps, but definitely not lighter. It's quite a bit more air retardent than most loose-fill fiberglass wools.

    Open blown cellulose is a LOT denser than R19 or R38 batts or open blown fiberglass, and blown into wall's it's denser than R15 or R21 fiberglass batts. Even dense packed fiberglass is only 1.8-2.2lbs per cubic foot, slightly lower density than 2-hole method low-density cellulose wall cavity fill. Dense packed cellulose starts a 3lbs per cubic foot, and 3.5lbs per cubic foot is pretty much the standard in most of New England.

  7. shtrum2 | | #7

    My bad about the weight; Dana is correct (cellulose is about 3x the weight of loose-fill fiberglass). And it can be an issue with gypsum board sheathing; occasionally there are blowouts that require repairs (especially at the seams). But it's a rare occurrence and shouldn't detract from anyone considering it . . . cellulose makes up 80 - 90% of the insulation installed through the weatherization program, and has been used for decades with good results.

  8. aalden | | #8

    More on rodents
    I pulled much poorly-installed and mouse infested fiberglass from our house and replaced it with Roxul, partially in hopes of deterring mice. Unfortunately, I've recently found where mice had built multiple nests in various locations using the Roxul. While not related to cellulose, I'd read that mice didn't much like Roxul. I'm reporting this so that others won't assume mice won't be a problem in Roxul insulation.

  9. jimg1126 | | #9

    Mice may not like Roxul as much as cellulose but the solution is to block all access points into your home. If there is a way in, they will find it.

  10. Insulwise | | #10

    I have been looking for an effective comparison of functional R-Values between blown fiberglass and blown cellulose in attics for a long time. I've owned an insulation company in the Pittsburgh area (Insulwise) specializing in retrofits for ten years now. I am also a BPI certified building analyst. I have been blowing cellulose and cellulose only (except around tubs, in basement walls and other moisture sensitive areas) in attics and walls since I started. I can't even guess as to how many times we've encountered homes that were 5, 10, 15, 20 years old (not that old!) that had an R-38 of super fluffy, bright white or pink blown fiberglass in their attics. And in every house if you ask the customer, "on a warm sunny day, what time does your 2nd floor start to heat up?" they'll say 11am - 1pm.
    After we air seal and top coat the attic to an R49 with cellulose insulation, the problem of heat gain in the 2nd floor (or whichever floor is below the attic) is significantly reduced. I get that we are increasing the R-Value from R38 to R49 as well as air sealing the attic floor, but the contrast in performance between the two materials has consistently been not even close. To that extent a fair number of homes in the Pittsburgh area have had their attics insulated with cellulose when new, and we are almost never called to work in those homes. The home owners don't experience the same comfort issues, ie "hot 2nd floors in the summer."
    Applegate makes a little device called a birdhouse that allows us to show customers the difference between blown fiberglass and cellulose using a heat lamp and thermometers. Flip the heat lamp on and within seconds the temp is climbing in the fiberglass, as where it takes much longer for the heat to begin making its way through the cellulose. I would rather have blown fiberglass than nothing, but it doesn't hold a candle to the effectiveness of blown cellulose in the homes that we work in here.
    When I've talked to other insulators in this areas that use blown fiberglass, they invariably seem to have zero background in building science, and will usually tell me they use it because "it's cleaner and less dusty to install." I will grant them that. But avoiding an extra 9 minutes of vacuuming on the way out the door is not a basis for choosing an insulating material in my view. My theory is that with blown fiberglass the fibers are simply not dense enough to provide an effective insulating layer. In attics it is unbelievably light and fluffy. And I understand why that diminishes its R-Value in cold temps (cold air is dense and heavy, and the colder it is, the more dense and heavy it is. This inclines it to "fall" through the blown fiberglass. As it falls it eventually comes into contact with warmth that is being conducted upward from the ceiling below. This causes a convection current of air within the fiberglass, that moves heat upward from the ceiling and into the attic. And this diminishing R-Value effect gets worse the colder and denser the air gets).
    Don't believe me? The next time your'e in an attic on a cold day that has a thick, fluffy layer of blown fiberglass in it, push your hand down through it. You will feel heat emanating up through it much sooner than you'll expect. Compare that with blown cellulose and you're usually 2-4" from the ceiling before you can feel heat with your fingers.
    I simply cannot believe that no one out there, the Dept of Energy, Energy Star, etc has put this one to bed sooner. In the meantime retrofitting blown fiberglass attics by air sealing them and top coating them with a layer of blown cellulose is a tremendous business that yields instant rewards for the homeowners in terms of immediate improved comfort, improved longevity of HVAC units, and reduced heating and cooling costs. Regarding mice and insects, we're not called to work in nearly as many homes or attics that have been insulated with cellulose as with fiberglass, so I don't think I can effectively compare the two. But I do know that we see various critter infestations in fiberglass on a consistent basis. With regard to an embodied energy comparison of the two that one I would think could only be answered by knowing the exact raw material stocks and energy inputs required of the two manufacturing operations. That info, alas, I am not privy to.

  11. user-1116814560 | | #11

    Blown in Fiberglass fan boys-what am I missing ?

    R factor, air movement, etc- it’s laughable to assert fiberglass is even competitive with cellulose, even if one considers ‘well in the long run cellose will decay, dissolve- no it won’t borate prevents that! And cellulose retains its thermal properties much better than fiberglass in extreme temps
    Noise reduction- cant fathom why the agency asked them to remove this claim-anyone whose ever been in a house with dense pack cellulose walls knows it’s makes an appreciable different in quietness
    Mold, bacteria-borate is an effective preventive agent-heck borax is used to disinfect things ! Yes mold doenst doesn’t feed to fiberglass-it does however thrive on the dust and organic particles that nest readily inside the air open center of less dense fiberglass
    Hygroscopic considerations-cellulose. Much better buffer for vapor (nobody’s talking bulk water here !) and vapor is determined largely by air movement,cellulose is denser and allows less air movement at any point in the assembly !
    Fire-Canadian study with actual identical structures proved cellulose superior, unsurprisingly as it limits air movement
    Respiratory issues-just get borate cellulose that’s is not recycled newsprint - I’d much rather my kids breath borax impregnated clean paper than any mineral fibers with formaldehyde. That may well reach smallest airway passage and not be biodegradable.
    If you walk through blown insulation you create a path, and cellulose settles back much easier to required depth than displaced fiberglass, tho it’s best to rake both back.m
    And most of all, it’s Its-easier to fake. Fiberglass install re depth and r factor as it’s so fluffy.
    Installers push fiberglass because they can get in and out quicker and use lesss product, ie increase margins. Andrew’s is comments are spot on -there are limited indications for fiberglass , very limited only !

    Ps try using borate only non recycled stabilized cellulose, with or without spray water - minimizes settling, dust
    PPS-there is a plausible hypothesis to explain rodents eschewing nesting in LOOSE blown celllose-it collapses the tunnel they make much more readily than fiberglass

  12. Expert Member
    MALCOLM TAYLOR | | #12


    "Blown in Fiberglass fan boys-what am I missing ?"

    Not a great start to a discussion among adults.

    1. user-1116814560 | | #13

      Malcolm-would appreciate a substantive rebuttal…..I am no cellulose fan boy, but given this is a ‘green’ building forum . I am deeply deeply skeptical of the tactics of the entrenched corporations, esp the spray foam manufacturers ,but others as well…and the transparent but Clever efforts to discredit a competitor than does not have as many patents and stockholders to appease makes me credulous as to motivations well beyond ‘facts’… list above reflects what I have uncovered…., if I am wrong am happy to change my perspective. ……So I repeat, what am I missing / ?

      1. Expert Member
        MALCOLM TAYLOR | | #14

        It's the "fan boy" part I'm suggesting might be better reserved for a reddit discussion.
        What is there to rebut? I don't see anyone in this thread who has disagreed with you.

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