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Improvements in high-R phenolic foam since the disastrous 1980s

Aaron Birkland | Posted in Green Products and Materials on

So I have been reading about the closed-cell phenolic and noticed the recent blog describing the use R-8/in Kingspan Kooltherm phenolic foam board in a retrofit.

The unique ability of these phenolic foams to achieve high R-values upwards of R-8 per inch seems to be established in testing and experience. However…

One of the comments referenced a report from Dow that mentions the fiasco of the 1980s involving acidic phenolic foam corroding metal roof materials. This ultimately resulted in phenolic foam insulation being pulled from the US market in 1992.

The Dow report suggests that the phenolic foam available today (at least the unnamed brands they tested) is still the same acidic foam from the 1980s (with a pH of 2.1-3.6), albeit with updated instructions/guidelines for safe use.

I came across a book L. Pilato (ed.), Phenolic Resins: A Century of Progress, DOI 10.1007/978-3-642-04714-5_9, # Springer-Verlag Berlin Heidelberg 2010 which mentions the kingspan foam by name:

The use of phenolic foam for thermal insulation in North America is being revisited mainly due to the efforts of Jan Kosny of Oak Ridge National Laboratories (ORNL, Clearwater, FL) and a consortium of collaborators consisting of Kingspan (UK), Kazak Composites (Woburn, MA), University of Southern California (USC) and others. Phenolic foam for thermal insulation was introduced in the 1980s in North America but was withdrawn from the market in 1992 due to corrosion problems occurring from roof decking components caused by relatively low pH (~2.5) foam. The current program sponsored by the US Department of Energy involves a re-examination of the role of acid catalysis of resole resins for foam with the objective of preparing phenolic foam with a pH of 6 and better foam adhesive and mechanical strength using cellulose fibers (proposed by Kosny) as reinforcing agent in the foam. Some success in increasing the pH of the foam has been achieved by Kingspan and Kazak Composites, members of the ORNL consortium, with insulation phenolic foam possessing a pH of ~5 by using a selective mildly, basic inorganic filler as an additive in the resole formulation [see patent]

Of course, none of this tells us what actual acidity characteristics of the kingspan foam on the shelves today. I can’t seem to find any reference to acidity
on the Kingspan site either. If the kingspan product on the market today is truly an improved product that has solved the corrosion problem of the 1980s, then it is very compelling. However, finding information on that has been like pulling teeth; hidden away in obscure academic references. I would think “low acid” would be a selling point for an industry that remembers having been burned in the past. Does anybody have any information or perspective that can shed light on this?

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  1. ranson | | #1

    It's not much to go by, but the MSDS of Kingspan Kooltherm products says "pH neutral under normal conditions."

  2. GBA Editor
    Martin Holladay | | #2

    Thanks for sharing what you've learned. I just sent an e-mail to Peter Yost, asking whether he has any more information to share on this issue.

  3. Peter Yost | | #3

    Aaron -

    Lots of good questions in your post. It's enough information and discussion that Martin and I agreed I will address in my next GBA blog (posted around May 15). Until then, I will check this string to see what other questions GBAers might have in this vein.

  4. Aaron Birkland | | #4

    Thank you very much for looking in to this, it really is hard finding specific information. "pH neutral under normal conditions" could mean anything from "the problem is solved" to "the pH is neutral as long as it does not get wet, as moisture is abnormal". There are many situations where that extra ~20% or so R value compared to polyurethane foams per unit thickness could come in real handy, even if it remains a specialty product for the foreseeable future.

  5. r_2 | | #5

    Could you address using this product as interior foundation wall (poured concrete crawlspace) insulation without further fire resistant cover? Documentation indicates this foam has a good fire rating.There will be no sources of flame in the crawlspace. Would it be sufficient to glue the foam to the concrete?

    Looking forward to your Blog post.

  6. GBA Editor
    Martin Holladay | | #6

    Q. "Could you address using this product as interior foundation wall (poured concrete crawlspace) insulation without further fire resistant cover?"

    A. Peter Yost's opinion (or my opinion) is irrelevant. The only opinion that matters is that of your local code enforcement official. So ask your local code enforcement official.

    If you want to marshal the paperwork needed to convince the official that this brand of rigid foam doesn't require protection with 1/2-inch drywall, you might ask Kingspan (a) if they have convinced any U.S. code officials of this approach, and (b) if they have any documents to back up the method.

    Q. "Would it be sufficient to glue the foam to the concrete?"

    A. Gluing rigid foam to concrete works, as long as (a) you use an adhesive that is compatible with the foam, and (b) you are able to apply pressure evenly to the rigid foam for several hours as the adhesive cures. I've done it in a crawlspace by using scrap pieces of plywood held in place by long pieces of framing lumber that are jammed against the opposite wall of the crawlspace.

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