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Fiberboard sheathing © Daniel Friedman at InspectApedia.comFiberboard Identification
Building Wall & Roof Sheathing, Insulating Board Identification Key

  • POST a QUESTION or COMMENT about fiberboard building sheathing: how to identify fiberboard products, fiberboard uses, fiberboard, Celotex, Homasote, Insulite & other brands, fiberboard ingredients, does fiberboard contain asbestos?

Fiberboard insulating sheathing identification guide:

Here we help identify and give information about the manufacture, ingredients & use of various fiberboard insulating sheathing products. We explain how to recognize/identify Celotex®, Homasote®, Masonite® Nu-Wood® and other insulating fiberboard building sheathing products used as exterior wall sheathing and as interior wall & ceiling surfaces.

This article describes and provides photographs that aid in identifying various insulating board sheathing materials used on building walls and roofs, such as "black-board", Barrett R-Brace, Eastman PS-57-73, Celotex, Homasote, Insulite, and Masonite, Upsonboard, Nu-Wood and other insulating board sheathing products.

In this article series we provide fiberboard product names and we describe the components, properties, and applications of various fiberboard, hardboard, and insulating board or sound deadening board products. We also answer questions such as do Celotex or Homasote or other fiberboard and insulating board products contain asbestos? fiberboard water resistance, fiberboard recycling.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Guide to Identify Fir-Tex™, Homasote®, Barrett®, Celotex®, Insulite, Nu-Wood, Upsonboard, & Fiberboard & Insulating Sheathing Board & Plasterboard Products

Celotex insulating lumber ad Low-density fiberboard panels and products trace their origin in the U.S. to Azel Storrs Lyman's 1858 patent for separating the fiber of wood and for the manufacture of paper and other purposes. (Jester 2014).

More significant for fiberboard products was W.E. Hale's patent for wallboard that described using fiberboard in construction (Hale 1870) and Cobb's patent for using a soft board made of straw in place of wood lath as a plaster base (Cobb 1871).

[Click to enlarge any image]

Jester explains that Cobb's straw fiber board was treated with cheap oil as a waterproofing agent, an idea that was elaborated by Homasote, Celotex, and the other big boy fiberboard producers of the 20th century.

The Agasote Millboard Co. (Trenton N.J.) was formed in 1909, and as Jester notes, by 1916 that company was producing the widely known Homasote brand fiberboard that probably has been a century-long thorn in the side of Celotex, Insulite, Nu-Wood, and Masonite.

By 1910 in the U.S., the manufacturer of fiberboard made these products available to builders and homeowners for use as a sheathing product that was used on wall exteriors, wall and ceiling interiors, and even as roof sheathing. In my personal experience, low-density fiberboard roof sheathing was a bad idea.

 

Article Series Contents

If you know the manufacturer name of your fiberboard, see the list below and click on the relevant link.

If you do not know the manufacturer, use your material sample or photos to review the below article to look for similar examples to help identify your fiberboard and its manufacturer.

How to Identify the Type of Fiberboard

Barrett Rigidwall Nail-Base insuating sheathing (C) InspectApedia.com JimIllustration: Barrett Board "Rigidwall" fiberboard used as an interior OR exterior wall nail base.

Below we discuss several observations and measurements that help classify fiberboard products.

Be sure to also read

UNIDENTIFIED FIBERBOARD PRODUCTS

On 2021-11-08 by [pseudonyms] - density is the best factor for classifying fiberboard

John Marker / Bob Ruteledge said:

Perhaps, the best factor for classifying fiberboard is the density. This is internationally recognized. There is a rather simple difference between pressed and
not pressed sheets hut the range of qualities is wide and there is an overlapping.

Another point which should be taken into consideration is the fact that wood fibers are blended occasionally with mineral fibers (such as asbestos), plastics and with other chemical additives. Some half-hard fiberboard contain no less than 20% of thermoplastic bonding agents.

[Poster's promotional link to an article by Kollman et als is deleted but cited in our reply below - Ed. ]

So does this mean that an old fiberboard ceiling or wall from 50s or 60s could have asbestos added in it?

This Q&A were posted originally at

FIBERBOARD CEILING & WALL COVERINGS by Bob Routeledge

and at

UNIDENTIFIED FIBERBOARD PRODUCTS by John Marker

On 2021-11-09 by (mod) - what is the right way to identify or classify fiberboard products?

Donnacona board catalog image from H. Beecham in Melbourne (C) Beecham & InspectApedia.comJohn Marker and Bob Routeledge:

Your posts under those names at two InspectApedia web pages were identical in content including a publication link. Unfortunately duplicate posts by various pseudonyms multiply the work for our moderators and do not reflect well on their author. Please post questions just once.

You cited Kollman et als (1975) whose work we include in the FIBERBOARD RESEARCH CITATIONS at the end of this article. Your reference to Kollmann's article does not address your question about the asbestos content in fiberboard products.

Note in that authors' own abstract (given at the end of this page) they use the phrase "ligno-cellulosic fibers " - that means plant-based fibers.

At FIBERBOARD DENSITY CLASSIFICATIONS you'll find details of the various densities of fiberboard products.

Really? But no typical building contractor nor homeowner is likely to know the actual measured density, such as in psf per cubic foot of material, for the fiberboard product they're considering.

In the Recommended Articles at the end of this page you will see a thorough exposition of the various types of fiberboard, such as HDF, MDF, LDF, and the properties of each;

You also seem to have tripped over a bit of confusion about identifying fiberboard sheathing products. There are at least four different fiberboard identification questions:

  1. What is the Type of fiberboard ?

    There is the 1st question of type of fiber board such as HDF, MDF, and LDF three different densities or hardness has of otherwise a similar material. Your question suggests these as the right way to identify hardboard.

    Older author (Kollman et als 1975) identified no less than seven different fiberboard product densities ranging from "non-compressed" up to extra-hard or "special densified" hardboard products. We describe those

    at FIBERBOARD DENSITY CLASSIFICATIONS

    But currently the three densities listed above are the most-widely-used.

    See DEFINITIONS, ENGINEERED WOOD HDF LDF LVL MDF MDO OSB where we describe the differences between HDF, LDF, MDF, etc. and where we discuss product or fiberboard densities.

    Also see SIDING HARDBOARD IDENTIFICATION & CLAIMS where we describe different hardboard brands, product failures, warranties

    But by "identify hardboard" (or MDF or LDF) many readers are asking something else.

    They want to identify the brand or product or they want to know the constituents of the product and they want to know if it contains asbestos.
  2. What is the Brand or manufacturer of fiberboard ?

    Separate from the fiberboard type question is that of identifying the specific brand of fiber board.

    At FIBERBOARD SHEATHING IDENTIFICATION (you are on this page) will find a complete list of fiberboard manufacturers, past and present, along with visual clues that can help identify specific brands.
  3. What is the Asbestos content in fiberboard ?

    Separate from the questions above is whether or not any fiberboard sheathing or siding, basically a plant product, contains asbestos: to which the answer is generally no with rare exceptions principally from cross-contamination.

    At SHEATHING, FIBERBOARD ASBESTOS CONTENT you will find an answer to that question along with explanation and citation of expert sources.

    Also see HARDBOARD Masonite™-like INGREDIENTS

Homasote roof insulating board (C) D Leen and D Friedman

  1. What is the intended use of the fiberboard product?

    Fiberboard products intended for exterior sheathing differ in treatment and moisture resistance from those intended for interior cladding of ceilings or walls.

    Fiberboard products intended for use as insulating exterior sheathing, or for interior wall coverings are generally MDF or LDF while fiberboard products intended for use as exterior siding or cladding - exposed to the weather - are HDF materials.

    Fiberboard products sold for interior use as a plaster base were in MDF form.

    Fiberboard products intended for uses where structural strength is required, such as for furniture, are generally HDF.

    Fiberboard products intended primarily for insulation in board form will usually be LDF

The articles in this series address all of those questions.

Excerpt from Types of Fiberboard, (Kollman 1975)

There are various types of fiberboard1, and unfortunately the terminology is not yet internationally standardized. [Note that this was in 1975 - Ed.] Nevertheless, one fundamental definition generally is recognized (FAO, 1958/1959, p. 4):

"Fiberboard is a board generic term encompassing sheet materials of widely varying densities manufactured from refined or partially refined wood fibres or other vegetable fibres.

Bonding agents and other materials may be incorporated in the manufacture of the board to increase strength, resistance to moisture, fire or decay or to improve some other property."

In the technical sense the ISO-definition is more precise:

"Sheet material generally exceeding 1.5 mm in thickness, manufactured from ligno-cellulosic fibers with the primary bond from the felting of the fibers and their inherent adhesive properties. Bonding materials and/or additives may be
added".·

FAO, OEEC and ISO used formally various definitions but the differences between them are without practical importance.

The classification of fiberboard into types is based on:

a) Type of raw material and method of fiber production;

b) Method of sheet formation;

c) Density of product (kg/m3 or g/cm3 or Ib./cu. ft.);

d) Kind and place of application.

Perhaps, the best factor for classifying fiberboard is the density. This is internationally recognized. There is a rather simple difference between pressed and not pressed sheets hut the range of qualities is wide and there is an overlapping.

Another point which should be taken into consideration is the fact that wood fibers are blended occasionally with mineral fibers (such as asbestos), plastics and with other chemical additives.

Some half-hard fiberboard contain no less than 20% of thermoplastic bonding agents.

The general term "fiberboard" is not only adopted for use in the publications of FAO and ECE, but is generally understood in the literature and in the industry.
FAO (1958/1959) gives a survey on the nomenclature.

Fiberboard is manufactured from separated fibers or bundles of them. This is a fundamental difference between fiberboard and particleboard. Fiberboard is produced by interfelting of fibers in such a way as to produce a mat or sheet.

The properties of the mat depend on the characteristic natural bonding of fibers between themselves. Chemicals may be added during manufacture with the aim to improve the cohesion and the water resistance.

Typical of fiberboard is the wide range in densities between 0.02 and about 1.45 g/cm3 (approx 1.25 and 901b/ cu. ft.).

Asbestos in fiberboard?

"Lignocellulosic fiber is a scientific name that refers to natural fiber, because all plant fibers are constructed by few constituents (cellulose, hemicelluloses, and lignin). Most of plant fibers contain 50%–70% of cellulose ..." - sciencedirect.com 2021/11/07

Asbestos is a mineral, not a plant.

Asbestos is indeed uncommon in any fiberboard products but there are exceptions, as we describe at

SHEATHING, FIBERBOARD ASBESTOS CONTENT

You will want to read that article.

Exterior Fiberboard Sheathing vs. Interior Fiberboard Walls & Ceilings

Barrett R-brace insulating sheathing (C) InspectApedia.com LauraFiberboard manufacturers such as those listed in this article series produced cellulose-based fiberboard or "caneboard" from a variety of plant- or wood-fiber sources. These panels were used as an insulating sheathing on building exteriors (mostly walls, rarely roofs).

Fiberboard panels were even more-widely used inside buildings as ceiling and wall paneling that was sometimes left unpainted, sometimes painted, and sometimes used as a plaster-base.

Exterior Fiberboard Sheathing

Insulating board sheathing has been widely used on building exterior walls, under roofs, and against masonry foundations in finished basements.

Exterior fiberboard, like the Allied Chemical / Barrett R-Brace sheathing shown here was usually treated to improve its water-resistance. If exterior-use fiberboard has a dark coating that's black or nearly-black it is usually an asphalt-based surface.

If the exterior-use fiberboard is tan or dark-brown in color it will probably also have a satin or slightly-shiny surface as it was treated with a water-repellent wax. Both types of fiberboard or "caneboard" sheathing may be impregnated throughout with a water repellent and often also with borate or other insect repellents.

That's true across the fiberboard-producing companies. You can often further-identify the fiberboard sheathing by a specific manufacturer if the sheathing bears stampings or printed product or company names.

Interior Fiberboard Sheathing

Interior-use fiberboard sheathing (C) InspectApedia.com E.H.

Interior fiberboard sheathing might also have been coated or treated with water repellents and insect repellents, but more-often the manufacturer's interior-use fiberboard products did not require and were not treated.

As a result interior-use fiberboard is more-likely to be light tan or brown in color with a natural finish - unless it was painted or plastered-over.

Our fiberboard photo shows the wall-cavity side of an interior-use fiberboard paneling that was found in the U.S. in an older home in Vermont.

You can see the characteristic linear screen-link texture on the fiberboard's surface. There are no manufacturer's marks. This photo, provided by an reader by email in 2018, identifies interior-use insulating board for which we can rule-out some brands like gray caneboards but beyond that the manufacturer is uncertain.

Below is another fiberboard photo provided by the same reader.

Interior of damaged or torn interior-use fiberboard insulating board panel (C) InspectApedia.com EH

Above we're looking at the interior of a fiberboard panel that has been split or torn during demolition. You can see the difference in surface texture - still without a certain identification of a specific manufacturer.

Below is a third fiberboard panel photo also provided by the same reader.

Cut and doubled-over fiberboard sheathing (C) InspectApedia.com EH

Above: the reader cut this fiberboard, perhaps with a sharp knife, and doubled it back over itself so that the wallboard sides that had been painted form a white line in the center of the image between the two board edges.

You can see the consistency of material in this insulating board. We can correctly state that this is a wood-based or wood-fiber based insulating board. Products made from post-consumer paper will be more gray in color throughout.

By color we can rule out Greylite, Homasote, and Upsonboard, but that's about our limit.

By color and texture this looks like but is not Beaverboard - Beaverboard bore identifying stampings or markings -

see details at IDENTIFY BEAVERBOARD FIBER PANELS & SHEATHING

I suspect this is an older Celotex insulating board product.

Allied Chemical / Barrett R-Brace Insulating Sheathing

Barrett Rigidwall Nail Base sheathing tested for asbestos: negative (C) InspectApedia.com MS

See details about idenytifying AB fiberboard including additional photos, asbestos test results and more information now found

at IDENTIFY ALLIED CHEMICAL / BARRETT R-Brace Insulating Board & Fiberboard - separate article

Identify Armstrong Fiberboard Sheathing

Armstrong fiberboard wall sheathing on a 1969 shed (C) InspectApedia.com Keith

Photos above showing the Armstrong logo on what looks like brown fiberboard insulating wall sheathing and below in closer view, are provided courtesy of InspectApedia.com reader Keith who found this material on a shed built in 1969. Discussed further, below.

Armstrong provided insulating board and sheathing products including under the brands listed just below:

Armstrong's Temlok was sold in various sizes such as 2' x 8', 4' x 8', 4' x 9' and was sold as a lower-cost competitor for horizontal wood plank sheathing.

Asbestos in Armstrong Temlok Sheathing? No, but ...

The product description itself does not include mention of use of asbestos, and other sources describe Temlok as made from Southern Pine, but this board was used in combination with several asbestos containing products such as a backer for asbestos-cement shingle siding and as a substrate to which asbestos could be bonded for other uses.

Armstrong Fiberboard Information Sources

On 2023-02-27 by InspectApedia Editor (mod) - any health concerns when removing this 1969 Armstrong sheathing board?

@Keith,

Keith, that looks like a wood- or plant-based fiberboard insulating sheathing (brown coarse woody fibers, perhaps with an asphaltic coating) bearing the Armstrong logo. While fiberboard is not normally an asbestos concern, you should definitely read

SHEATHING, FIBERBOARD ASBESTOS CONTENT

If you want to be meticulous you'd have the sheathing and its coating tested for low levels of asbestos including from possible cross-contamination - but read the article I suggested above, first.

If you decide to do testing, keep us informed.

I'll add your photo and what we can find about that Armstrong sheathing product above on this page at

IDENTIFY Armstrong Fiberboard Sheathing

Watch out: even without asbestos, if the materials you're demolishing were sprayed with pesticide or are moldy or if you simply create high levels of dust, all of those can be respiratory and health hazards. At the very least you'd wear respiratory protection.

On 2023-02-27 by Keith

Armstrong fiberboard wall sheathing on a 1969 shed (C) InspectApedia.com Keith

Hello,

I'm replacing the siding on my shed built back in 1969 and I wanted to get some info on the material used under the siding and if there would be any health concerns with removing it

I really appreciate the help!

I was going to replace the siding on my shed that was built back in 1969 but I wanted to find out some info on the material that was used under the siding and if there is any health concerns with removing it

I really appreciate the help!

Photos of Keith's fiberboard sheathing with the Armstrong logo are shown above in this section.

Beaver Board & History of How Fiberboard Was & Is Manufactured

Beaver Board trademark © Daniel FriedmanBeaver Board was marked on the back of each sheet with an ink-stamped trademark and brand.

If a single fiberboard sheathing product wanted to go up against Homasote as claiming the most-generic use of its name to describe low-density fiberboard sheathing made from wood fibers, or plant fibers, it'd be Beaver Board.

Details about identifying true Beaverboard panels are

at BEAVERBOARD IDENTIFICATION.

However "beaverboard" as well as "celotex" are often used as a generic product name. That's understandable, because Beaverboard and other low-density fiberboard sheathing or wallboard products were similar in being comprised of relatively-homogenous plant-fibers bonded together by the interlacing of the fibers and treated with a waterproofing agent.

While no doubt some ugly logs that wouldn't have made a nice stud or joist were ground into chips for processing, I think that most of these sheathing products were considered to take enormous advantage of sawmill waste in the form of wood chips, sawdust, and wood scrap, or for some manufacturers, in the form of other plant materials such as straw, sugar cane, or bagasse.

Where wood was the initial material the wood was chopped into chips, sized, ground to finer size, and smashed into individual wood cells using steam and rollers. The combination of steam or water and pressure permitted the fibers to bond together into a sheet that was further pressed by hydraulic rams and rollers called platens (think of a huge typewriter platen or roller if you were born before 1980).

Randomly-crossed wood fibers make a strong product, a realization that appeared again later as MDF and HDF and similar products. To get the plant or wood fibers to adhere to one another beyond their mechanical arm linking, adhesives were used during the fiber consolidation process.

Jester names silicate of soda, flour paste, glues, dextrin, plaster of paris, waterglass and clay, rosin, turpentine, paraffin wax (see HOMASOTE® IDENTIFICATION), asphalt (giving a nice dark black color to the fiberboard panels and making them unattractive to termites and carpenter ants). (Jester 2014 pp 90-90).

Insect damaged beaver board © Daniel Friedman at InspectApedia.com

Photo above: low density fiberboard is not, however absolutely insect-proof, as my photo shows. More about this particular insect damage is at FIBERBOARD SHEATHING MOLD CONTAMINATION

Beaverboard, as other low density fiberboard products, was then trimmed, treated with a water repellent, and possibly colored, or for fancier products like Nuwood™ cut to bevels or tooled.

Caneboard sheathing

Caneboard was a fiberboard panel made from sugar cane.

Details are at IDENIFY CANEBOARD PANEL.

Celotex® Insulating Board and Fiberboard Products

Celotex produced its first insulating sheathing board from bagasse (sugar cane waste) in 1920.

Our photographs below show Celotex® insulating board with an older Celotex fiberboard building sheathing board at left and a more recent Celotex insulating board product shown at below-right.

Celotex tuff-R insulating board © Daniel Friedman at InspectApedia.com Celotex old insulating board © Daniel Friedman at InspectApedia.com

Details for identifying Celotex at at

IDENTIFY Celotex® Insulating Board and Fiberboard Products

and at CELOTEX HISTORY & PRODUCTS

Identify Dierks Fiberboard Sheathing Products

On 2022-10-04 by InspectApedia (Editor) (mod) - History of Dierks Forestry, Lumber Products, & 1960's wall sheathing

@Kinga J,

Dierks was a, among other trade names, an Arkansas lumber company (Arkansas-based Dierks Forests, Inc.—which amassed holdings of 1.75 million acres of timberland—was one of the largest family-owned landholding entities in the United States until its sale to Weyerhaeuser Company in 1969.- source: https://encyclopediaofarkansas.net/entries/dierks-forests-inc-8188/

After over 75 years in the lumber business, Dierks Forest, Inc., was purchased by Weyerhaeuser for $317 million in 1969. - source: https://www.arkansasheritage.com/arkansas-register/dierks-lumber-company-building

So it's most-likely that your Dierk's intermediate wall sheathing (between framing and exterior siding) was produced by that company during that era.

That Dierk's produced lumber and other building products including insulating sheathing board.

And we found Dierk's - an Iowa lumber company (dating from the 1880's).

And we found Dierk's - an Oklahoma lumber company :

CHOCTAW LUMBER COMPANY.

The Choctaw Lumber Company appeared in McCurtain County in 1906. The company's founders, brothers Hans and Herman Dierks, had been profitably engaged in retail lumber businesses in Iowa, Nebraska, and North Dakota from 1880 to 1895.

The retail business named Dierks Brothers continued until it expanded in 1895 to become Dierks Lumber and Coal Company, headquartered in Lincoln, Nebraska. Joined in management by brothers Peter and Henry, they continued to expand the Nebraska operations.

In 1897 the company moved its headquarters to Kansas City, Missouri, and was incorporated in 1898. - source: https://www.okhistory.org/publications/enc/entry.php?entry=CH050

Insulating sheathing would have been, and is labeled in your photo, a Dierk's product. The photo isn't quite sharp (a close-up would help) but it looks like fiberboard such as discussed above on this page.

The possibility of asbestos content of these basically plant-based products, is discussed at

FIBERBOARD SHEATHING ASBESTOS CONTENT

https://inspectapedia.com/structure/Fiberboard-Sheathing-Asbestos.php

**Please** tell us the location of your building and we can comment further.

On 2022-10-04 by Kinga J - what kind of fiberboard is this, marked Dierks

What kind 9sbfiberboard is it ? Does it contain asbestos. House is dated 1960

[Photo above showing Dierks ... Intermediate ... tan fiberboard exterior wall insulating sheathing board. ]

Also see DIERKS LUMBER COMPANY HISTORY [PDF] Arkansas Heritage - retrieved 2022/10/04, Source: arkansasheritage.com/arkansas-register/dierks-lumber-company-building

Identify Donnacona Board Sheathing & Acoustic Panels

1965 Donnacona fiberboard insulation sheating on a BC Canada home (C) InspectApedia.com John Vere

Donnaconnaboard may be light coloured or greyish or it can be a dark brown, almost black asphalt-like coated board.

See details and more identification photos, history, tests for Donnacona board now found

at IDENTIFY Donnacona Fiberboard acoustic & insulating panels - separate article

Photo of Donnacona blackote Fiberboard from a British Columbia home built in 1965, provided courtesy of InspectApedia reader John Vere.

Identify Eastman Sheathing Board

Eastman insulating sheathing, apparently cellulose-based fiber insulating board stamped with code PS 57-73 - [citations and research in process]

Identify Fir-Tex, FirTex, Fire-Tex Fiberboard - Kaiser Gypsum

Fir-Tex insulating board catalog, 1945 - cited & discussed at InspectApedia.comFir-Tex, in some literature FirTex or Fire-Tex or FireTex was a fiberboard product, made principally of wood pulp and was produced by the Fir-Tex Insulating Board Co., an Oregon corporation operating at St. Helens, Oregon, engaged in the manufacturer of insulating wall board from at least the mid 1930s.

Note that asbestos, Asbestos, plaster of Paris, clay, turpentine, paraffin wax, or other materials were added to some mixes to improve fire resistance and produce other desirable qualities such as stiffness, hardness, smooth surfaces, increased strength, or durability. (Wilson 2007)

The trademark was associated with / registered by Kaiser Gypsum Co. - 1958-06-10.

The trademark category description includes

Composition wood fiberboard, insulating sheathing, roofdeck materials, insulating tile, building board, utility board, insulating plank, and acoustical tile

International Class

017 - Rubber, gutta-percha, gum, asbestos, mica and goods made from these materials and not included in other classes; plastics in extruded form for use in manufacture; packing, stopping and insulating materials; flexible pipes, not of metal.

019 - Building materials (non-metallic); non-metallic rigid pipes for building; asphalt, pitch and bitumen; non-metallic transportable buildings; monuments, not of metal.

- Rubber, gutta-percha, gum, asbestos, mica and goods made from these materials and not included in other classes; plastics in extruded form for use in manufacture; packing, stopping and insulating materials; flexible pipes, not of metal.

Building materials (non-metallic); non-metallic rigid pipes for building; asphalt, pitch and bitumen; non-metallic transportable buildings; monuments, not of metal.

Fir-Tex or FireTex FirTex trademark, expired, Kaiser Gypsum cited & discussed at InspectApedia.com


Identify Homasote® Brand Boards & Panels

Homasote panels showing its characteristic gray-tan color (C) InspectApedia.com DF Homasote® wallboard and panels used for building sheathing are a cellulose-based product made from re-cycled paper to produce an internally homogeneous (non-layered) gray or gray-tan panel. .

Homasote® Identification: check color & texture & cross section

Despite widespread use of the word Homasote® to describe brown fibrous and soft board panels, actually Homasote is gray or in my OPINION gray-tan in color, as it's produced from post-consumer paper.

However once installed the product may have been painted or covered-over so an inspector cannot assume that she will always find the gray color without some digging into the structure.

The Homasote picture shown here is from a discontinued product previously sold at Lowes stores.

According to Homasote®,

[Homasote brand fiberboard products in] cross section would not show layers of fiber since our products, unlike other fiberboards, are not layered.

With aging our products normally have a yellowish brown tint otherwise they are gray.

In all cases, unsanded Homasote Products all have very visible patterns on the face and back side surfaces. As far as I can tell, none of the samples shown below [at UNIDENTIFIED FIBERBOARD PRODUCTS] have our mold patterns.

Each fiber is coated with a wax emulsion thus making the panel weather resistant.

Homasote® company history, current product list, product composition details, more identificatin photographs & contact information are

at HOMASOTE HISTORY & PRODUCTS

Reader Question: Is it OK to re-side a home with Homasote building sheathing on its walls?

My home was built in the early 1940s and it was re-sided around 1994 (possibly a bit later but that's all the info we have). There are what we thought was sheetrock on the outside, but someone suggested it may be Homasote boards from when the house was originally built.

Two questions, if they are these boards from 50 years ago (at the time the house was re-sided), was that ok to do based on housing codes? Could they contain asbestos? Thanks. - K 12/2/2011

Reply: Yes

I've not found any building code issue constraining the procedure of re-siding a home because of the type of exterior sheathing used on the structure. The asbestos question is addressed in earlier FAQs addressed above. Wood or plant fibers are not asbestos materials.

Watch out: fiberboard sheathing should be protected from water that penetrates some building siding systems (such as aluminum or vinyl siding) by installing a water or moisture barrier - housewrap.

See HOUSEWRAP AIR & VAPOR BARRIERS

 

Identify Graylite - Insulite, Cellulose FiberBoard Insulating Board & Plaster Base

Insulite plasterboard from patent app.

Insulite and Graylite were a cellulose-based (all wood fiber) insulating board or sheathing material that, unlike Celotex, was made from wood pulp byproduct or sawmill tailings fibers.

See details and identification photos, history, research, lab tests and more information about Graylite and Insulite now found

at IDENTIFY Insulite, or Graylite cellulose fiber board product useful for plasterboard - separate article

Additional information about Graylite and Insulite is found in

FIBERBOARD PLASTER BASE SYSTEMS

 


Identify IKO Fiberboard Sheathing Products

IKO fiberboard sheathing on a 1980 home on Vancouver Island - (C) InspectApedia.com David

Photos: IKO fiberboard insulating sheathing on a 1980 home on Vancouver Island.

IKO produces and has produced a range of building insulating sheathing products of various materials, including fiberboard insulating sheathing stamped with a gray-white IKO logo as shown in photos here, courtesy of InspectApedia reader David in 2023.

See identification photos, guides, research, history of Iko fiberboared sheathing now found

at IDENTIFY IKO Fiberboard & Other Insulating Sheathing - separate article

Johns Manville Fiberboard Sheathing Identification

Above: Johns Manville's product name and imprint on an older U.S. home. This "blackboard" sheathing product, widely-used in the U.S. at least by the 1960s, was typically installed as 1/2-inch thick 4' x 8' fiberboard panels that served as both a nail base for siding and insulating sheathing.

The photo below of Johns-Manville Strongboard fiberboard insulating sheathing was provided courtesy of InspectApedia.com reader Ann.

On 2023-07-31 by Ann - debris from Johns Manville Strongboard: should I be worried about asbestos?

I had my siding redone and underneath there is this blackboard pictured "Johns Manville Strongboard".

It was left alone and wrapped with Hardie wrap then the new cement fiberboard on top, but a lot of nails and other pieces attached were disturbed and my lawn was left with a ton of tiny debris all over. The house is from the early 60's so this could be original.

Should I be worried about asbestos here or does this type of board not contain that? The siding that was removed was vinyl with the plastic underneath FYI so no ACM there if that is helpful.

Thank you in advance!

On 2023-08-01 by InspectApedia Publisher (mod)

@Ann,

Generally, fiberboard sheathing is a plant-based product - not asbestos, but I'd still want that debris cleaned-up.

In the company's 1949 sheathing product catalog their insulating sheathing was describd as made from "clean pine fibers". - source: Johns-Manville ASBESTOS FLEXBOARD INSULATING BOARD PRODUCTS [PDF] (1949) Catalog

We are researching further for any documents that give specifics about the ingredients in 1960s Johns-Manville blackboard sheathing and will add that here.

A more complete answer to your question is at

SHEATHING, FIBERBOARD ASBESTOS CONTENT

And you will also want to read

SHEATHING, FIBERBOARD ASBESTOS CONTENT where we include a section on BLACKBOARD ASBESTOS CONTENT

Once looking at those two articles, don't hesitate to ask any follow-up questions needed.

For completeness, you can see a complete list of the Johns-Manville products known to contain asbestos, by scrolling down to that company name in our article:

ASBESTOS PRODUCING COMPANIES & TRUSTS

Thanks

DF

This reader's Q&A were originally posted at HOW TO CONTACT InspectApedia.com 

 

Masonite™ and other hardboard Sheet and Siding Building Materials

Masonite hardboard © Daniel Friedman at InspectApedia.com

Our photo (left) shows the back side of an early hardboard interior-use product labeled "Genuine4 Masonite Quartrboard".

At HARDBOARD MASONITE™ & OTHER BRANDS we include a table translating mill codes to hardboard manufacturer for all brands of hardboard siding.

History, more photos, & dates along with a description of the ingredients in Masonite™ hardboard products are given

at HARDBOARD Masonite™-like INGREDIENTS

More about hardboard sheet products used on building interiors is found

at DRYWALL, FIBERBOARD, PLASTER INTERIORS

 

Identify National Gypsum's Gold Bond® Cellulose-based Insulating Board

Gold bond wood fiber insulating board (C) InspectApedia.com HR ... Gold bond wood fiber insulating board (C) InspectApedia.com HR

Shown here in photos provided by a reader are a portion of the Gold Bond logo used by National Gypsum on "black" or "brown" board insulating board or IB.

The second photo plainly shows brown cellulose-like fibers that would be expected to be a wood or plant product based material.

Gold bond wood fiber insulating board (C) InspectApedia.com HR

National Gypsum produced a very wide range of building products, a number of which contained asbestos, principally in products based on gypsum board or plaster board, or cement or asbestos cement board and coatings.

At ASBESTOS PRODUCING COMPANIES & TRUSTS where you will find National Gypsum in that alphabetic list, we discuss a number of Gold Bond™ products, all produced by National Gypsum, that did indeed contain asbestos.

 

Nu-Wood Fiberboard Wall & Ceiling Covering Product Identification

Nu-Wood wall & ceiling patterns & textures aid in identification of Nu-Wood (C) InspectApedia.com 2017

Nu-Wood ® fiberboard panels, also referred to as NuWood or Nu Wood paneling or ceiling tiles were a low-density fiberboard panels used on walls & ceilings & as a plaster lath support. They were produced by the Wood Conversion Company in St. Paul, Minnesota who also produced Balsam Wool.

The parent Wood Conversion Company was incorporated in 1921 in Delaware by eleven stockholding companies, including the Weyerhaeuser firms. The Wood Conversion Company headquarters was located in Cloquet, Minnesota.

According to the company's product literature, some Nu-Wood fiberboard was thus plastered over while other installations were left with the original factory color coating.

Keep in mind that a 1940's home that used Nu-Wood wall or ceiling panels may well have been painted-over, plastered over, or later even laminated-over with a layer of more modern drywall.

[Click to enlarge any image]

Our details about the identifying details for Nu-Wood fiberboard panels are now found

at IDENTIFY NU-WOOD PANELS - a separate article.


Pinex Fiberboard - Insulating Board "Softboard"

Pinex Board advertisement, 1943 Gisborne Herald - at InspectApedia.com

This advertisement for PINEX BOARD appeared in the Gisborne Herald on November 2, 1943.

Pinex is a specific brand of soft wood-fibre based insulating board that, in New Zealand, is often used as a generic name" for low-density softboard or fibreboard.

Pinex and equivalents was widely used as an insulating sheathing in New Zealand between 1941 and 1960, and appears also as finished ceilings, sometimes coated with plaster or covered by wallpaper or occasionally painted.

See details at

IDENTIFY PINEX FIBERBOARD - separate article


Photo of Russian or Italian Fiberboard Sheathing / Insulating Board

Insulating board in a Russian-made pre-fab home now located in northern Italy (C) InspectApedia.com MarkQuestion:

2020/01/25 Mark said:

Hi there, fantastic trove of information you’ve got here! Any ideas as to what these panels are? They were used as insulation in the walls

Reply:

Thanks for the compliment Mark, we work hard on this so I'm really grateful when you find our information useful.

About your panels, from the surface appearance first and the edge appearance second, those look like fiberboard insulating panels.

See SHEATHING, FIBERBOARD - home - for photo examples of fiberboard, or

you could go right to FIBERBOARD SHEATHING IDENTIFICATION [readers are now on this page]

or scroll through the examples of other types of insulation given

at INSULATION IDENTIFICATION GUIDE

There are also densely-packed mineral-fibre MINERAL WOOL insulation products that may have appeared as board-type insulating panels but I don't think those would have that brown wood-fibre-like surface that I see in your photo.

Can you tell me following?

1. the country and city where these are located

2. the type and age of building where they were found

3. exactly how they were applied or located? I mean, I'd expect these to be nailed to studs on the interior or exterior surface of a wall. If you found them in some other position that'd be interesting.

Reader follow-up:

Russian or Italian or other source of wood based fiberboard insulating panels in a home in Northern Italy (C) InspectApedia.com MarkThe house is in northern Italy and is for the most part a prefabricated wooden house imported from Russia in the 70s.

These panels have been used in various locations around the house such as in between the studs as insulation, over roof space floorboards as insulation and as recently discovered as an extra layer to double up the battens for the external siding (thus increasing the air gap). Will try to get some more photos if that helps.

We have removed almost all of it, where possible, but the fact that the most worn and weather beaten panels break up easily, leaving dust behind, has left me wondering as to its makeup and its potential to be a health hazard!

Many thanks. Mark

Moderator reply:

Thanks Mark, clearly that is not at all likely to be a US-made fiberboard product.

Yes a sharp photo of the material edge and another of the surface would be great as would be any stamps or labels on the material.

From your description it sounds as if someone got a supply of fiberboard and cut it to insert between studs in an effort to improve the wall's R-value.

Generally this is a wood product, made from various species of vegetable matter depending on the country and area of origin, often pine board sawdust but given that the home originated in Russia the wood species could of course be different if the panels were made there - or in Italy or in another nearby country.

It doesn't usually contain asbestos (with a few uncommon exceptions).

In my opinion the smaller particles in just about any building dust are at the very least, respiratory irritants, possibly allergenic, and potentially harmful. It's always smart to wear a dust mask/respirator and to clean up the dust.

Russian or Italian or other source of wood based fiberboard insulating panels in a home in Northern Italy (C) InspectApedia.com MarkSome companies impregnated the panels with waxes, asphalt or other stabilizers to improve moisture resistance but any of them can become soft and crumbly with wetting, moisture, age. Which is why you won't see this material used in homes in Venice.

Reader follow-up:

2020/01/26 Additional photos of this wood-based or cellulose- fiberboard are posted for identification.

Mark said:
Follow up photos to the one posted higher up the page ... trying to identify these panels that are possibly Italian /European or Russian in origin. Many thanks.

Moderator reply:

Certainly that looks like a wood fiber "fiberboard" Mark;

While in a few cases careful forensic microscopy or even spectroscopy can identify specific fibres used by specific fiberboard manufacturers (such as bagasse or sugar cane) in general you'd need to look for other means to know who made the product.

Those include a research of the building's age, site of construction, construction history, bills of materials, and of course any manufacturer's stamps or tags found on the product.


Question: History of Shumite fiberboard (?) insulating board? Shu Mite? Shamite?

I am looking at blueprints for a sound stage from 1936, and I see a layer of 1/2" Shumite specified between roof rafters (and wall studs) and the 2" mineral wool they used for sound insulation. I can't find anything on Google called "Shumite," is this a material you are familiar with?

Insulite and plaster board are also specified on these drawings, so it should not be the same material. In some places Insulite is specified to replace Shumite. I turn to you because I learned what Insulite was from your website!

Anything helps. Thank you! - Anonymous by private email 2020/10/15

Moderator reply:

Thanks for the interesting question on Shumite, Anon. I, too, have not yet found a reference to that 1930s product that I infer, from your note, was, from the context of use, probably a type of sound-insulating board.

It's possible that Shumite was named for an individual, as the name Shumite does appear both in biblical text (2 Kings 4:12 et als; Shunammite was a native inhabitant of Shunem north of Mt. Gilboa in ancient Palestine) and in modern times a Shumite was listed among U.S. civil war prisoners.

If you can post or email me a photo of the document so that we can be sure of its spelling and any distinctive identification data that would help my research.


Sundeala Board

Sundeala teacherboard or pinboard at Amazon uk - not currently available, cited & discussed as used in artwork at InspectApedia.com

Sundeala board is a rigid or semi-rigid cellulose product made from recycled paper, produced first in 1898 by the Impermeable Millboard Company Ltd, in the U.K., and who continue to the present as the Sundeala company.

See details at SUNDEALA BOARD COMPOSITION & HISTORY


How to Identify Upson Board

Upson Board Trademark

Upson board embossed its marking into the board itself, and a "Blue Center" runs through every piece of the board.

Examine a cross section of the board for this characteristic blue material.


US Gypsum Insulating Sheathing

Details on identifying and finding properties of US Gypsum's sheathing products are now found

at IDENTIFY US GYPSUM INSULATING SHEATHING

USG's products included USG Insulation Formboard - a wood fiber product, and Pyrofill, a gypsum concrete product that included wood chips, shavings, fibers. Asbestos was used in some other products or in their installation support, for example in USG's roofing sheathing systems.

Identify Weyerhaeuser IB FIberboard or Insulating Board Products

Collected from several sources, as Weyerhaeuser manufactured and sold fiberboard or insulating board products under several product names and brands, we provide photos and examples below.

Note: the company's name is occasionally mis-spelled by people as We ye rhauser

On 2023-07-10 by Bo Astrup - what can you tell me about this exterior wall sheathing

Weyerhaeuser IB Insulating Board Sheathing (C) InspectApedia.com Astrup

Any pointers to this exterior wall sheet

Weyerhaeuser IB Insulating Board Sheathing (C) InspectApedia.com Astrup

On 2023-07-10 by InspectApedia Publisher (mod)

@Bo Astrup,

Thats a Weyerhaeuser Intermediate Insulating Board "IB-Rated 5122" that is combustible - which is why it was not intended to be left exposed. It's intended to be covered with siding or if indoors, with drywall / gypsum board.

I notice as an aside some loose electrical wires - if those are carrying live voltage that's a more-immediate safety hazard.

If you're asking about asbestos, that's explained over at SHEATHING, FIBERBOARD ASBESTOS CONTENT https://inspectapedia.com/structure/Fiberboard-Sheathing-Asbestos.php

Thank you for the photos and question - we will copy the images and our reply into the article above to help other readers.

Please tell us the building location and its age and use. And let me know if you have other questions.

Thanks
DF

Below: Dierks fiberboard by Weyerhaeuser

See IDENTIFY Dierks Fiberboard Sheathing

Below:

Also see IDENTIFY NU-WOOD PANELS

History & Patents for Weyerhaeuser- Older Insulating Board IB Products

Frederick, Weyerhaeuser, and John S. Busch. MEANS for INSULATING WALLS [PDF] U.S. Patent 2,030,668, issued February 11, 1936. At InspectApedia.com

Above: an illustration from Frederick, Weyerhaeuser, and John S. Busch 1936 Patent 2,030,668, issued February 11, 1936. for wood-fiber insulating board. Cited below.

[Click to enlarge any image]

Un-Labeled Fiberboard Products

Fiberboard sheathing like Homasote © Daniel Friedman at InspectApedia.com

I photographed this insulating board under the overhanging floor portion of a raised ranch in Dutchess County New York. This is a brown insulating fiberboard product that is not Homasote™. What is it?

Often we can, however, use the color and texture to at least rule out some fiberboard products and thus to narrow the possible identification down to a short list.

See UNIDENTIFIED FIBERBOARD PRODUCTS for help in identifying fiberboard or insulating board products that look like this and that do not bear an identifying mark or stamp.

Cement fiberboard by Architonic at InspectApedia.com

Above: wood fibre-reinforced cement board panels describe by the Architonic, a UK source of building products who insists on keeping the actual product manufacturer and identity a secret, Architonic ID: 1184351, prompting us to decline to cite the Archi tonic website directly.

See details at WOOD FIBRE INSULATING PANELS - large coarse fibres


Plant-Fibre Based Board Products & Fiberboard History Research

Georgia Pacific Fiberboard sheathing 1/2 inch R 1.31 at InspectApedia.com

Above: Georgia-Pacific R- 1.31, 0.5-in x 4-ft x 8-ft Unfaced Cellulose Board Insulation with Sound Barrier - previously sold at Lowes building supply stores (not in 2022 - Ed.) [Shown above from a 2020 Lowes ad] Lowes description of this product was a bit confusing, "R- 1.31, 0.5-in x 4-ft x 8-ft Unfaced Cellulose Foam Board Insulation with Sound Barrier" - note that it's a plant-fibre or wood-fiber product, not foam board - Ed.

 

 

Reader Comments & Q&A - also see the FAQs series linked-to below

On 2023-09-11 by InspectApedia Publisher - can I cover my fiberboard ceiling panels with paper or paint?

@Camilla Watson,

I think your follow-up photo here shows a thin insulating fiberboard product underneath what may be a plywood roof sheathing.

You'll see that the answer we gave you on the other page where you posted will still be appropriate.

I think you posted the same questions and we have already replied at

https://inspectapedia.com/interiors/Ceiling_Finish_Choices.php

Please take a look there and don't hesitate to post any follow-up questions or comments .

On 2023-09-11 by Camilla Watson

I took a closer photo of the ceiling (I believe it is the underside of the original roof deck), in an area that has been damaged so you can see the orange/brownish color of the interior of the fiberboard.

Again it is a 1957 ranch house, you can see part of the exposed (painted) wood beam as well- the white paper coating of the fiberboard has gotten quite shabby over the years,

I want to either paint it, or possibly cover with paintable wall paper so it just looks clean and white, but I am unsure if the fiberboard can take paint, or even press and stick adhesive of a textured ceiling paper product without breaking down, delaminating etc.

thin insulating fiberboard (C) InspectApedia.com Camilla

On 2023-09-10 by Camilla Watson

Hi, I have a 1957 California Ranch house with vaulted exposed beam ceilings- I do not know what product I'm working with, as far as the underside of the original roof deck or roof sheathing material that forms my ceilings.

It is now quite dingy/dirty and needs covering. Can I paint this material? Or can I paper over it? I'm looking to cover it with something very lightweight, as I don't believe the beams can handle much extra weight (such as dry wall) without sagging.

See photo. I also posted in ceilings area.

thin insulating fiberboard (C) InspectApedia.com Camilla

On 2023-09-03 by InspectApedia DF (mod)

@Nikkismirl,

Glad we can be of help.

We've worked hard on this material for decades, so are really grateful when a reader finds it useful and trustworthy.

We welcome your photos, questions, criticism or suggestions.

On 2023-09-03 by Nikki Smirl

@InspectApedia Publisher, thank you so much for being so responsive. This resource is so valuable. I really appreciate it!

On 2023-09-02 by InspectApedia Publisher

@Nikkismirl,

That sure looks like an MDF subfloor board - thanks for the photos. I explain my mistake in detailed replies to your earlier posts.

On 2023-09-02 by InspectApedia Publisher

@Nikkismirl, and for other readers,

Here is a better look at Roberts SmoothEdge carpet tack strips - that in Nikkismirl's photo I mistook for a drywall edge tape - my bad.

On 2023-09-02 by InspectApedia Publisher - MDF - "Medium Density Fiberboard"

@Nikkismirl,

No, the photo above is either a chipboard or a fiberboard product - depending on how hard (chipboard) or soft (fiberboard or MDF - "Medium Density Fiberboard". The much softer fiberboard sheathing shown above on this page is very soft (LDF Low Density Fiberboard) - you can push a nail or your thumbnail into it by hand.

For help getting our products and their names straight see

DEFINITIONS, ENGINEERED WOOD HDF LDF LVL MDF MDO OSB

In contrast, Drywall (gypsum board or "sheetrock") as well as other interior wallboard products are described at

DRYWALL, FIBERBOARD, PLASTER INTERIORS

and examples of individual Drywall brands and identification stamps are at

DRYWALL IDENTIFICATION STAMPS


MY MISTAKE: your photo does NOT show drywall.

Now, I apologize for causing some confusion here.

Your photo from two days ago included what LOOKED like an edge tape - I couldn't read that text until I enlarged the photo and even now some of it is too blurry to make out - so if you can post a sharper photo that would be very helpful.

But on zooming in I realize now that I was NOT seeing an edge tape on drywall but rather a carpet tack strip made by Roberts.

My mistake.

And now that I understand (since it's a carpet tack strip) that I am looking at a floor, not a wall.

ON a floor we would not expect to find fiberboard or other soft insulating board products (though there are a few exceptions) - so we're back to MDF or HDF wood board subflooring.

Sorry for my mistake.

MDF subfloor with wheel logo stamp (C) InspectApedia.com NikkiSmirl

On 2023-09-02 by Nikkismirl

Hi! I am getting a bit confused. Do you think this looks like gypsum board?

Here is a photo of what the interior looks like

MDF subfloor with wheel logo stamp (C) InspectApedia.com NikkiSmirl

On 2023-09-01 by InspectApedia Publisher - "Celtic wheel" logo is clearly a product or brand logo

@Nikkismirl,

I don't see fiberboard in your photo - I see what looks like drywall (gypsum board).

Compare what you're seeing to the fiberboard identification photos above on this page.

And be sure to see FIBERBOARD SHEATHING ASBESTOS CONTENT

https://inspectapedia.com/structure/Fiberboard-Sheathing-Asbestos.php

Chipboard - as you have identified other material in other photos - is a wood product - principally sawdust and glue.

That "Celtic wheel" logo is clearly a product or brand logo, familiar but I can't name it and haven't yet found it by search.

If you can find any legible text in those stampings that would be helpful.

Here's an emphasized version of the logo stamp:

MDF board logo (C) InspectApedia.com NikkiSmirl

On 2023-09-01 by Nikki smirl

@InspectApedia-911, thanks! Any thoughts on the fiberboard? Have you ever seen that logo on the fiberboard to help identify if it is asbestos containing?

On 2023-08-31 by InspectApedia-911 (mod) - white stuff in your photo is a coating or paint

@Nikkismirl,

I agree that the white stuff in your photo is a coating or paint. It's not likely that this is a significant risk to you.

Generally if you're not demolishing materials are creating a dusty mess the potential risks to you are even less.

The anxiety may be more harmful than the material itself so try to not let that carry you away.

On 2023-08-30 by Nikkismirl - does my chipboard contain asbestos?

And now we have pulled up some more of the carpet and carpet padding and found a thick layer of white plaster like material on the fiberboard/chipboard. Any thoughts on what this could be?

We got a sample to take to a lab for asbestos testing, but I would be so grateful for any additional input.

It looks like the yet to be identified white later extends over the fiberboard AND the layer of actually plywood which was installed in 2006 according to permit records we were able to locate.

The white stuff looks more like paint and is not as thick on the plywood side but hopefully it is all the same material and is something manufactured post 1986, but still freaking out that we have a big problem on our hands.

MDF subfloor with wheel logo stamp (C) InspectApedia.com NikkiSmirl

On 2023-08-30 by Nikkismirl

Hello. We just tore up some carpet and carpet padding in a 1936 home in Minnesota. The carpet and carpet padding was laid down sometime in the early 2000s, but under the carpet padding is a chipboard/fiberboard material that has the logo stamped on it as shown in the image.

I am concerned that the chipboard was installed prior to 1986 and may contain asbestos. I am also going to include additional photos. The chipboard is heavily stained and has some white patches on it.

I am wondering if the white patches are blue or adhesive that also may contain asbestos.

MDF subfloor with wheel logo stamp (C) InspectApedia.com NikkiSmirl

On 2023-07-10 by InspectApedia Publisher - Weyerhauser Intermediate Insulating Board "IB-Rated 5122" that is combustible

@Bo Astrup,

Thats a Weyerhauser Intermediate Insulating Board "IB-Rated 5122" that is combustible - which is why it was not intended to be left exposed. It's intended to be covered with siding or if indoors, with drywall / gypsum board.

I notice as an aside some loose electrical wires - if those are carrying live voltage that's a more-immediate safety hazard.

Please see your images and our reply in the article above where it will help other readers.

On 2023-07-10 by Bo Astrup

Any pointers to this exterior wall sheet

Weyerhauser Intermediate Insulating Board "IB-Rated 5122" (C) InspectApedia.com Bo



...

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FIBERBOARD SHEATHING IDENTIFICATION at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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