Asbestos containing acoustic ceiling tilesCatalog of Celotex® Insulating & Sheathing products that contain asbestos or that are asbestos-free

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Asbestos-containing products made by the Celotex corporation.

The following list names and comments on building products such as ceiling tiles and many other Celotex® brand building products & articles listed by some sources as believed to contain asbestos.

This article series assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection. We provide photographs and descriptive text of asbestos insulation and other asbestos-containing products to permit identification of definite, probable, or possible asbestos materials in buildings.

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Alphabetical list of Celotex™ insulating & other building products believed to contain or not contain asbestos

Asbestos containing acoustic ceiling tiles

[Click to enlarge any image]

Celo-Siding Celotex siding board (C) InspectApedia op cit 1943

Below: photo of Celotex cane-board insulating sheathing along with packabge labeling, provided by an reader . [Click to enlarge any image]

Celotx cane board insuilating  sheathing  (C)  A B Celotx cane board insuilating  sheathing  (C)  A B Celotx cane board insuilating  sheathing  (C)  A B

Celotex gypsum board interior wall system in 1943 (C) InspectApedia original source Architectural Record 1943 p. 16

Celotex asbestos board (C) InspectApedia op cit 1943

Cemesto building panels from Celotex (C) InspectApedia op cit 1943

Celotex gypsum roof panels (C) InspectAPedia 1943 op cit


What is Celotex Insulating Lumber? Did it contain asbestos?

Celotex insulating lumber Reader question: I have a home built in 1940 that used a brown fiber board called "Celotex Insulating Lumber" looks like is was designed to be used as sheathing and lath. Made in either Chicago on Louisiana. Anyone familiar with this? Or know if it contained asbestos? - Dan Theisen 1/30/12


Dan, Celotex, a Chicago company, has been a producer of a wide variety of insulating sheathing boards for a long time and the company continues to produce modern insulating board products as well.

Our illustration (left) shows Celotex insulating lumber on the exterior of a Lebanon PA home. This insulating board is a wood-fiber product (actually made of bagasse fibers obtained from sugar cane, that is, cellulose) that we document in detail at SHEATHING, FIBERBOARD.

Asbestos was not among the product's ingredients. Only if such products were produced at a manufacturing facility that also produced asbestos-containing products might there have been a risk of cross-contamination that could result in the detection of asbestos in the cellulose-based materials.

Reader Question: asbestos in Celotex Gypsum Board (drywall) 4X8 panels?

Celotex tapered edge drywall gypsum board (C) InspectAPedia5/21/2014 Jesse said:

I am buying a house that has unused Celotex Gypsum Board (drywall) 4X8 panels in the basement... the owner has offered to leave them for me to use when I finish the basement, but I don't know if they contain asbestos and can't find an answer online.


Jesse if you refer to celo.rock gypsum panels, some of those may indeed contain asbestos. Use the CONTACT link found at the bottom of any InspectApedia web page to send me sharp photos of both sides and an edge of the product and of any stampings or markings and I can comment further.

On receipt of photo (above) This looks like a quite recent tapered edge product. If so it would not be expected to contain asbestos. Do you know when it was bought?

Reader follow-up:

The gentleman I'm buying it from says it is 10-15 years old... so '99-'04 would be my best guess. The house was built in '9.. so definitely bought after then.


sounds fine

Reader Question: Does this 1968-era Celo-Rok® Gypsum board contain asbestos?

Celotex Celo-Rok gypsum board (C) InspectApedia SQ Celotex Celo-Rok gypsum board (C) InspectApedia SQ

I was so happy to locate your site. We are remodeling our inherited mom's house and have a whole lot of drywall to replace. We really need to find out if it contains asbestos. I think I located the name of it on your site but it says 'May contain asbestos'. I have attached a couple of pictures in hopes that you could help identify and determine for us.

The drywall is Celotex Celo-Rok® gypsum board.

Thank you so much for any help you can provide. - Anon [by private email] 19 Sept 2015


Celo-Rok Catalog cover 1947 (C) InspectApediaAside from product labeling and visual appearance, it would be most helpful if we knew the age of the home and age of the wallboard or about when it was installed.

Certainly Celo-Rok products from the 1940's were advertised as containing asbestos in some of that product line. However your photographs, the paper taping edging on the drywall panels, and the blue ink numeric stamp all look to me like much more modern products than those from the 1940's.

Celotex Celo-Rok® gypsum products were widely sold in the 1940's. However from my reading of the advertised properties of Celotex products (from 1943) it is clear that the company did not explicitly name asbestos as an ingredient in all of its sheathing products.

In addition to the 1943 Celotex advertisement cited in this article, I note that an advertisement for books on asbestos cites and quotes a 1947 Celo-Rok product catalog produced by the Celotex Corporation [shown at left] that refers to "Wood or Asbestos Shingles" (the latter would have properly been called asbestos-cement shingles) as a roof covering beneath which a Celotex Celo-Rok roofing panel might be applied.

The use of the word "asbestos" in referring to roof shingles is perhaps a source of confusion about asbetos as an ingredient in Celo-Rok®.

Similarly, "How You Can Build Better Homes at Lower Cost", from the same era cites:

Important contributions to "Economy Home" construction are the new types of patented fasteners specially developed for
applying wood or asbestos shingles directly to Celotex Insulating Sheathing.
One section of Glen Oaks Village in Bellerose, Long Island, N.Y., built by Gross-Morton of Jamaic or L. I., N. Y. There are 3800 apartments in this huge, beautiful garden-type development. Celotex insulating Sheathing used throughout. C. A. Hemphill Associates, Evanston, Illinois, used Celotex Insulating Sheathing on these fine homes in Forest Glen subdivision, Winnetka, III. - retrieved 21 Sept 2015 original source: /HowYouCanBuildBetter HomesAtLowerCost/HowYouCanBuildBetterHomesAtLowerCost_djvu.txt

In the 1940's Celotex produced and marketed "Celo-Rok Anchor Lath" as a substitute for traditional wood lath in wall plastering applications. The company produced a "cane-board" lath product as well.

These texts do not cite asbestos in the sheathing or lath product itself.

I suspect that your gypsum wallboard does not contain asbestos, though I do not know that for a fact. My reasoning is that at least into the 1960's the use of asbestos in building products was considered a positive feature as it added both strength and fire resistance. It was common for a manufacturer to include asbestos and its properties in product literature and in product advertisements.

Bottom line: to know for certain if your specific Celo-Rok wallboard contains asbestos you'd need to send a sample to a certified asbestos testing lab.

As it's quite inexpensive, and as it could make a significant difference in the cost in an extensive renovation work where all drywall is being removed, I would have a lab test performed to confirm the presence or absence of asbestos in your 1960's vintage Celo-Roc. That's because:

  1. We have not found unequivocal data clearly stating the presence or absence of asbestos in interior gypsum board produced with the Celo-Roc brand
  2. If you found asbestos in a dust-creating material that was going to be removed during extensive demolition and that couldn't be removed with practically no debris and dust production, an asbestos-dust-containment job will be much more costly than straightforward demo of asbestos-free drywall.

If you take that action (about $50. U.S.) you can send me the bill and in any case I ask that you keep us informed of a test result as what you learn will help other readers.

Question: was asbestos used in Celotex Thermax foam core insulating board sheathing?

Celotex Thermax TM Insulating board  (C) JW

Jason Wojnowiak said:

I have a picture of some Celotex. IMG_5620.JPG
Would you know if this has asbestos?

Reply: some Celotex Thermax™ laminate insulating board products contained asbestos at least in patent disclosures


Celotex Thermax™ was (and is currently as a Dow Thermax™ product) a foil-faced insulating board comprised chiefly of foam insulation, laminated with aluminum foil or possibly kraft paper.

Asbestos appeared in some, probably not all, foam insulating boards made up to the early to mid 1980's, particularly or more likely in fire-resistant products that incorporated a layer of asbestos paper.

Looking at photos you sent by email, I think your Thermax sheathing is a later polyisocyaurate foam insulating board reinforced with fiberglass and faced with aluminum foil, though of course an expert inspection of your material might find something different. Please see details about Celotex Thermax and its successor Dow insulating sheathing board, now found

History of the Celotex Corporation: Background on Celotex & Asbestos

Celotex product description from 1943, Architectural Record October 1943 p. 16 -

While an expert lab test using polarized light microscopy may be needed to identify the specific type of asbestos fiber, or to identify the presence of asbestos in air or dust samples, many asbestos-containing building products not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases.

See ASBESTOS FIREPROOFING SPRAY-On Coatings for photos of dangerous tremolite asbestos ceiling panels and photos of spray-on asbestos fireproofing coatings.


and see ASBESTOS DUCTS, HVAC a field identification guide to visual detection of asbestos in and on heating and cooling system ducts and flue vents.

Also see Micro-Photographs of Dust from the World Trade Center collapse following the 9/1

References & Research on Asbestos in Celotex Products


Continue reading at ASBESTOS CEILING TILES, Asbestos-Containing or select a topic from the More Reading links or topic ARTICLE INDEX shown below.

Or see




POLYISOCYANURATE FOAM BOARD - more about Celotex and Dow insulating sheathing

Suggested citation for this web page

CELOTEX ASBESTOS PRODUCTS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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