Blog Post

Formaldehyde-Based Foam Insulation Back from the Dead

Urea formaldehyde foam insulation (UFFI) has been out of the spotlight, but going into a lot of buildings—often being referred to as Amino Foam.

In working on major updates and expansions to The BuildingGreen Guide to Insulation, we’ve had an opportunity to dig into some of the insulation products out there that you don't hear so much about. Some of what we’re found has been surprising.

Anyone remember urea formaldehyde foam insulation (UFFI)? Back in the late 1970s and early 1980s it was the ultimate bad guy of the insulation world. Installed in hundreds of thousands of homes in the U.S. and Canada following the 1973 Energy Crisis, UFFI was found to emit high levels of formaldehyde in some circumstances and shrink considerably, resulting in performance problems.

The Canadian government spent millions of dollars insulating 80,000 to 100,000 homes with this insulation, then spent many more millions uninstalling it when reports of problems emerged. Canada banned the product, as did the Consumer Products Safety Commission in 1982 in the U.S.—though the latter later reversed the ban a year later.

The industry largely disappeared. While there had been 39 manufacturers of UFFI in 1977 and upwards of 1,500 installers, that dropped to just a handful by the early-eighties. Most of us pretty much forgot about the product.

UFFI is still around

The UFFI industry shrank to just seven manufacturers by 1981, then two large producers, Borden and Ciba-Geigy, ceased production. But the remaining five companies have continued to produce UFFI, though under different names. Most of those companies have gone to significant effort to avoid any association with UFFI.


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Among the five manufacturers of UFFI today, you will variously see the material referred to as “injection foam,” “amino foam,” “aminoplast foam,” “tri-polymer foam,” “dry-resin foam,” and various combinations thereof. The only reference you’re unlikely to see is “urea-formaldehyde,” and if you ask manufacturers what the stuff is most will go to great lengths to obfuscate their response.

Used for insulating concrete-block construction

The primary application for UFFI today is to insulate hollow concrete masonry units (CMUs) or concrete blocks—and I think it is a fairly good solution for such buildings. It can be also used as a retrofit insulation for wood-frame cavity walls, but there are better products for wood-frame construction.

What is it?

To really understand what UFFI is, one may need a degree in polymer chemistry. cfiFOAM, which is the most forthcoming of the manufacturers in production today, describes the material as being “part of the family of amine/furan resins consisting of phenol, urea and melamine, coupled with an aldehyde.” The company explains in a fact sheet that “amino resins are thermosetting materials produced by reacting amine groups (NH3) with an aldehyde, such as formaldehyde.”

The reaction results in a blend of three different polymers, monomethylol, dimethylol, and trimethylol-substituted urea, which leads one manufacturer, C.P. Chemical, to refer to its insulation as TriPolymer Foam. This resin is further reacted with an acid catalyst in a condensation process, and the resultant resin is dried (sometimes in a kiln) to produce a powdered, dry resin that can be stored and easily shipped.

Insulation contractors use specialized equipment to mix the powdered resin with water, surfactant, and catalyst to create the injectable foam. By carefully controlling the mix of these different components, the release of free formaldehyde—one of the main problems in the past—is greatly reduced.

Phosphoric acid is often used in this process, and that chemical imparts some fairly good fire retardant properties. To the best of my knowledge, there are no halogenated flame retardants used in any of the amino foams—which is a significant benefit of the material.

Consistency of shaving cream

Amino foams are fully expanded at the time of installation—unlike polyurethane foams, which expand as they are sprayed into a cavity or onto a surface.

The foams are very flowable, and, according to Bob Sullivan of cfiFOAM, can fill vertically as much as 18 feet, though he cautions that rapid setting can be problematic with rises above 12 feet. The flowability allows the insulation to fill concrete cores very effectively, including around hardened mortar protruding into the cores.

Misleading information on performance

Along with confusing information about what the amino foams are—and their history as UFFI—some manufacturers have grossly misleading claims about performance. The material insulates to about R-4.6 per inch, which is quite good. You may see claims of performance as high as R-5.1 per inch, but if you read the fine print, you’ll find that the higher performance claim assumes measurement at 25°F instead of the more standard 75°F.

More significantly, you may see exaggerated claims about the resulting R-value of CMU walls insulated with amino foam. Tailored Chemical Products, the manufacturer of Core-Fill 500, continues to claim exaggerated R-values above R-14 for 8-inch CMU walls insulated with the company’s UFFI insulation.

In reality, the R-value of an 8-inch CMU wall insulated with amino foam is highly dependent of the density of the concrete. With very low-density blocks—85 pounds per cubic foot (pcf)—two-core, blocks insulated with this insulation provide a whole-wall R-value of 11.3. With heavier (more dense) concrete blocks the R-values drop. With medium-density blocks (105 pcf) the whole-wall insulating value drops to R-8.2, and with high-density block (125 pcf), the whole-wall R-value drops to R-6.0. The dramatic difference between the R-value of the foam insulation alone and insulated concrete blocks results from thermal bridging through the concrete webs in the blocks.

Formaldehyde offgassing

The major problem that led to the near destruction of the UFFI industry was the fact that the material can offgas formaldehyde. Back in 1982, when the Consumer Products Safety Commission temporarily banned the material, formaldehyde was considered a “probable human carcinogen,” but the hazard warning has been upgraded to “known carcinogen.”

Formaldehyde offgassing continues to be a concern with amino foams, but improvements in the chemistry by all of the manufacturers has significantly reduced offgassing. Amino foam insulation cannot be used in a buildings going through Living Building Challenge certification (because formaldehyde is a “red list” chemical that is banned in such buildings), but for a typical CMU building, the formaldehyde issue is not nearly as significant as it once was.

Shrinkage of foam

More significant than formaldehyde offgassing, I believe, is shrinkage that can occur with amino foams. Typical shrinkage after installation is 0.5%, but in some cases shrinkage can be as much as 2%, or even 4% according to some sources. According to cfiFOAM, the impact of shrinkage is accounted for in the reported whole-wall R-values by at least that company, but it’s still a big concern.

Bottom line

UFFI (a.k.a. injection-installed amino foam) has some quite attractive features, and I believe these to be a fairly good option for concrete masonry construction. Very significantly, it is the only foam-plastic insulation that does not contain halogenated flame retardants. Were it not for the shrinkage and the lack of clear information and transparency by most of the amino foam industry, I would feel even better about it.

To see our complete listing of UFFI manufacturers, along with similar evaluations of dozens of other insulation types, see The BuildingGreen Guide to Insulation.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.

Published October 30, 2013

(2013, October 30). Formaldehyde-Based Foam Insulation Back from the Dead. Retrieved from

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January 27, 2021 - 7:13 pm

Alex, thanks for the background and update on use of injection foam insulation.  I am considering having my 1927 bungalow in the Pacific NW insulated with RetroFoam made by PolyMaster.  We bought this home and then found that there is no insulation in the walls and the injection from the exterior is least intrusive.  Your Bottom Line comments say that the injection foam is "fairly good option" for concrete masonry construction, but you don't summarize your position on residential wood frame construction.  I think that earlier in the article you mention that there are better optoins for wood frame but I didn't see those mentioned.  Do you cover this in another article?  Thanks for your insights!