Rock wool or mineral wool insulation appearance:

This article describes what mineral wool insulation looks like. Mineral wool or "rock wool" or slag wool may be installed as chopped or stranded material, usually white but possibly gray or with yellow, gold or other colors imparted by a resin binder.

This mineral wool or "rock wool" insulation article series illustrates and describes mineral wool or "rock wool" and slag wool insulation materials. This document assists building buyers, owners or inspectors who need to identify various insulation materials in buildings by simple visual inspection.

We provide photographs and descriptive text of various types of mineral wool insulation and describe its properties, how it is made, health and maintenance concerns, and its insulating values.

Variations in Appearance of Mineral Wool Products

Mineral wool is generally a dull white but may be fairly homogeneous gray (shown earlier on this page) or mineral wool may look very dark, even black, especially in older buildings.

White Mineral Wool Insulation

The most-common appearance of mineral wool insulation is shown in our photo of the white material in the attic eaves of our photograph.

Notice that while this insulation is mostly white, it contains some dark gray-white areas. Those darker areas are not mold but may be dust particles from other sources.

Often the black or gray discoloration is due to particle deposition from air bypass leaks. You'll see that some of the mineral wool photos in this article series also include newer yellowish product, typically a resin binder.

Mineral wool, that some folks call slag wool, rock wool, stone wool, or "rockwool" may appear in chopped form, in batts, in faced batts, and in chopped stringy material that we illustrate later in this article.

Mineral wool also appears in a range of colours, principally whitish but also gray, yellow and white, pink and white, or dull white with colored flecks of included materials.

Rockwool is also a trademark discussed at MINERAL WOOL - ROCK WOOL INSULATION

Gray-white Mineral Wool Insulation

Some mineral wool insulation was produced to include additional fibers of flax, jute or other materials to resist settling.

Below is a photograph of Johns Manville's Spintex™ Rock Wool Insulation showing the most-common gray-white color of this insulating material.

Spintex™ foil faced insulating batts produced by Manville were sold in thicknesses up to 6 inches. Rock wool is not an asbestos material.

While asbestos is not normally found in rock wool or mineral wool, there were some (rare) exceptions, discussed

at ASBESTOS IN MINERAL WOOL / STONE WOOL.

Let's look at more photos of the appearance of mineral wool insulation.

Pink Mineral Wool Insulation

As you can see in our first photo below, mineral wool insulation is not necessarily stark white.

And this pink mineral wool might even be mistaken for fiberglass insulation. It's not.

Gray Mineral Wool or Rockwool Insulation

...

Above: Gray Rockwool insulation produced by JM - Johns Manville, found in a Rochester New York home built in 1946.

Johns Manville Semi-Thik "felt batt insulation" (Rock Wool)

I just wanted to share insulation information for gray Johns Manville insulating batts faced with kraft paper and labeled as JM Felt Semi-Thik and as JM Super Felt insulation product no. H1-43A.

I recently bought a home and decided to fix some drywall in a side room. I came across some insulation that made me nervous.

It was Johns Manville Super felt batt insulation. The paper had product no. H1-43A.

I sent samples to be tested but also did some research and couldn’t find this particular one that had brown paper with red print.

I also called Johns Manville and was told it would have been for the 50’s or 60’s and they destroyed records. They could not identify the product. The attorney actually told me she never heard of the super felt line.

Good news the test came back negative for asbestos.

I am attaching photos. I tested the super felt and the loose fill in the pictures. - Anonymous by private email - 2022/02/09

Moderator Reply:

Thank you for the JM Mineral Wool or "Rockwool" photos and asbestos test report. Readers wondering about asbestos in these JM products should also

see SPINTEX MINERAL WOOL PROPERTIES - MANSVILLE

Gray-Brown Mineral Wool Insulation

Above and below our photos of mineral gray-brownish mineral wool insulation, seen close-up, illustrates a contemporary product installed in a New York home in 2002.

This mineral wool insulation is mostly white but contains darker areas of yellowish resin and colored fragments of cellulose (paper) insulation.

Below: a close-up of a dense-packed gray-brown mineral-wool insulating batt at a Vassar College construction site in Poughkeepsie, New York in 2016.

Below: gray-brown-tan mineral wool insulation blown into a wall - Thermafiber Insul-Fill from Owens Corning.

More photos of this insulation product are

at MINERAL WOOL - ROCK WOOL INSULATION

Stringy White Long-Fiber Mineral Wool Insulation

Question: is this white stringy insulation mineral wool?

This insulation looks like balls of string and feels like a type of mineral wool. Please let me know if you can identify it.

[Click to enlarge any image]

The house where this insulation is installed is located in Hackettstown, NJ, and was built in 1930. But many changes and additions to the home have occurred since then.

Some areas lack any insulation at all. The insulation pictured is loose fill with no identifying facing or bags found. [The buyer ]is in construction and has also never seen an insulation material like this.

The only question is whether it could possibly be asbestos containing. [We think ] that, although it does not look typical of an asbestos containing material, the only way we could rule it out is to send a sample to a lab for analysis.

- Anonymous home inspector, by private email, 2016/11/15

Reply:

To me too it looks like mineral wool insulation, though I've not seen this specific twisted pattern before. As you probably saw, there are also some scraps of yellow fiberglass insulation mixed in with what is probably antique mineral wool insulation loose-filled in place.

Other readers are welcome to help out with a comment about this insulation using the page bottom COMMENTS BOX or you can send us email and photos using the page top or bottom CONTACT link .

Our photo showing a close look at white mineral wool insulation was taken in a home built in 2002. To compare these mineral wool insulation pictures with fiberglass insulation,

see FIBERGLASS INSULATION IDENTIFICATION & PROPERTIES.

The age and location of the home are consistent with use of mineral wool insulation, and as we discussed by email, it would be not impossible but quite unusual to find asbestos attic insulation in any residential home much less in this form.

I speculate that this mineral wool product was produced in longer wound strands for ease of handling during manual placement in the attic floor.

Later alternative "blown-in" and "poured-in" insulation products had to be chopped for easier placement requiring less hand labor.

If you want to send me a sample to examine in our lab - if you have some - let me know. I should at least be able to rule cotton and asbestos out and probably can rule mineral-fiber or slag wool insulation "in".

Researching for images of "rope-like mineral wool" it is interesting to note that there are current manufacturers of thermal insulation mineral wool rope and braid, such as the Zibo Jiuqiang refractory Co., a Chinese firm.

Dark Brown & Mixed White/Black Mineral Wool Insulation

Question: is this dark brown fibrous insulation rock wool?

My brother posted this photo under the name Josh and asked if this insulation was asbestos and asked if you could identify the material.

We had someone doing work in our house recently that caused some insulation to fall from our attic, and he was very dramatic about it being asbestos-contaminated insulation.

Everything I could find suggested it likely wasn't, but the information online can of course be a bit contradictory depending on the source.

Reply: Lab analysis of your sample found mineral wool wool or "rock wool" / slag wool insulation.

Initial report:

The insulation that you mailed to me is mineral wool or "rock wool" - of various sizes and colors, mostly white (or colorless); there is black asphalt, perhaps as a binder, in some of the material and some fibers that are dark are most-likely made from cinders or slag.

There are typical contaminants of old insulation: fungal hyphal fragments, a few fungal spores, non-fungal granular debris. I didn't see rodent nor insect fragments but then, by no means was the examination exhaustive. When I have photos and other notes ready I'll pass that on to you as well.'

I did not detect fiberglass nor asbestos fibers in the three sub-samples (from your whole mailing) that I examined.

Photographs of your insulation in our lab are at the end

of MINERAL WOOL by MICROSCOPE where we include details about our examination of this rock wool sample.

At MINERAL WOOL / STONE WOOL ASBESTOS CONTENT you will see that mineral wool is not an asbestos product though there could have been instances of mineral wool having been cross-contaminated with asbestos - an uncommon situation.

 

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2024-01-07 by InspectApedia Publisher - vermiculite insulation in 1890 home near Toronto

@Giulia,

That is almost certainly vermiculite insulation. As you will read in this article series, some vermiculite contains asbestos and so you would either treat it as if it is a hazardous material or if you were facing a costly clean up you might want to have a sample tested.

In the live link above to our article index on building insulation you'll find articles on vermiculite.

On 2024-01-07 by Giulia

We also came across this stuff (vermiculite?) in the chimney of our 1890s house. What’s the best practice to remove it? Likelihood of asbestos?

On 2024-01-07 by InspectApedia Publisher - mineral wool insulation in 1890 home near Toronto

@Giulia,

I agree that this photo looks like mineral wool or rockwool.

Occasionally we can be fooled and mistake chopped fiberglass for mineral wool as they are similar but I'm betting on mineral wall here.

On 2024-01-07 by Giulia

I’m hoping you can help me identify this type of attic insulation (mineral wool?) and the likelihood that it contains asbestos. House is build in 1890 (near Toronto), but I’m not sure when the attic was insulated. Thanks so much!

On 2023-10-16 by InspectApedia Publisher

@Matt,

Best information on this question is at

CELLULOSE LOOSE FILL INSULATION - home https://inspectapedia.com/insulation/Cellulose_Insulation.php

On 2023-10-16 by Matt

@InspectApedia DF,

Could not find any paper in it, looks like it may possibly have pieces of cardboard though. It’s all brown with no other color to it. Iv never seen insulation like this and was wondering if it would have asbestos in it.

On 2023-10-16 by InspectApedia DF (mod) - 1930s cellulose insulation

@Matt,

That doesn't look like mineral wool; more like a plant fiber or cellulose. Look closely: are there any tiny bits of paper or newsprint?

On 2023-10-16 by Matt

This is behind the old lath and plaster walls in my house. Was blown in from the exterior. Back in the 1900’s. Is this rock wool?

On 2023-09-24 by InspectApedia DF (mod)

@Alex,

Yes, looks mineral wool insulation.

On 2023-09-24 by Alex - 1915 Minnesota mineral wool insulation

Hello,

Thank you for providing this resource.

I think I have mineral wool insulation in my attic, seen in the attached image. Do you agree? Small pliers for scale. The surface sawdust is from a roofing project in process.

This is under the attic floorboards in a 1915 house in Minneapolis, MN. There are a few fiberglass batts above the floorboards as well. I took a sample from the photo area and plan to get it tested for asbestos, before doing some electrical work. After that's done, blow-in cellulose will be added.

Thank you!

On 2023-09-08 by InspectApedia DF (mod) - mineral wool insulation

@Brian,

Yes, that looks like mineral wool insulation.

On 2023-09-08 by Brian

Hello,
I bought an older home a few years ago and am trying to identify what type of material my attic insulation is. I attached an image below. Is it safe to safe that this is mineral wool? Thank you for your help.

On 2023-09-08 by InspectApedia Publisher (mod) - visual appearance of Owens Corning Thermafiber INSUL-FILL Blown In Attic Insulation - compare with mineral wool mixed with recycled newsprint (cellulose)

@Sam,

Just above is Thermafiber's example photo of their mineral wool INSUL-FILL attic blown-in insulation

Your second photo looks like mineral wool insulation but it definitely contains some bits of paper with text on it - almost certainly recycled newsprint. Is it from the same material as was in your first photo? That product looked quite different in that I thought I saw more such paper bits.

Below is an enlargement from your second mineral wool insulation sample, showing newsprint.

You can see what Thermafiber INSUL-FILL looks like and read or download PDFs of its product specifications on our page

MINERAL WOOL - ROCK WOOL INSULATION

If a closer look at your installed insulation in the attic - try a simple magnifying glass - is showing many small bits of paper and newsprint (look for letters on the paper bits) then it sure doesn't look like the Owens Corning Thermafiber's own photo of their product to me.

Here is what Owens Corning Thermafiber says about the composition of this insulation:

What is Thermafiber® mineral wool insulation?

Thermafiber® mineral wool insulation is made from naturally occurring rocks and recycled slag. Slag is a by-product of the steel industry. Rocks, of various types, are an abundant natural resource.

These raw materials are melted at 2,600°F and fiberized (spun into fibers) to create Thermafiber® mineral wool insulation products with an industry leading minimum of 70 percent recycled content 1.

Thermafiber® mineral wool insulation is naturally non-combustible and fire resistant up to 1093° C (2000° F) making it great for providing protection to structures.

Source:

• Owens Corning Thermafiber FREQUENTLY-ASKED QUESTIONS [PDF] (2017) - retrieved 2023/09/08, original source: thermafiber.ca/wp-content/uploads/2018/05/600022A-Thermafiber-FAQ-Document-ENG.pdf

The note 1 in that information source reads:

1 Recycled content as verified by ICC-ES.

Also see this

• ICC-ES VAR ENVIRONMENTAL REPORT VAR-1025 on Thermafiber Insulation [PDF] (2023) on Owens Corning Mineral Wool Products (Thermafiber) - retrieved 2023/09/08, original source: icc-es.org/wp-content/uploads/report-directory/VAR-1025.pdf
  Excerpt:
  3.0 DESCRIPTION
  
  Thermafiber(R) insulation products consist of a mixture of volcanic roc, slag, natural rock, various binders, and oil.
  

Nothing in this product description explicitly mentions a composition of Thermofiber insulation that includes cellulose or newsprint or similar materials like that we see clearly in your sample.

However while the contents of "recycled content" might be a bit fuzzy all of the text describing Thermafiber describes the product as an inorganic material made from rocks and slag. That's mineral wool, not paper. Paper is made from wood pulp or plant materials - which are organic.

"Our mineral wool contains a minimum of 70% recycled content, and it’s non-combustible, inorganic and mold-resistant. Thermafiber is the #1 specified brand of commercial mineral wool." - source: ABOUT THERMOFIBER [PDF] - original source: https://www.thermafiber.com/about-thermafiber/

So in my OPINION, if in fact it includes recycled paper such as newsprint, then the company's description of the Thermofiber as inorganic mineral fiber may be a bit incomplete and confujsing.

BUT the ICC-ES report notes that

Recycled content building materials shall comply with one of the following

1. Contain not less than 25 percent combined post-consumer and pre-consumer recovered material, and shall comply with section 505.2.3

2. Contain not less than 50 percent combined post-consumer and pre-consumer recovered materials.

In my OPINION the vague term "post-consumer recovered material" could include newsprint even though the product is described as made from the mineral products I cited earlier.

For a final answer to this question I suggest contacting the company's Thermfibert technical services department at 1-888-834-2371 or email Thermafi berInsolutions@owenscorning.com.

Ask the company if they include recycled newsprint (cellulose) in their Thermafiber INSUL-FILL products (which is fine if they do) and if they say not, then your insulation product is most likely something else.

In that case, consider mailing them a sample for them to look for themselves. The company would not be happy for someone to be installing something represented as theirs but that is from another source.

Insulation R-valuel Fire Rating, Mold Resistance of Mineral Wool Mixed with Newsprint

All of this is beside any question about the efficacy of your insulation but in my opinion it's perfectly reasonable to want to know what insulation was installed and that it has proper insulating value and fire safety ratings as you'd expect.

About your concern for mold resistance, mineral wool itself is in my experience more mold-resistant than fiberglass insulation.

I do not know for fact about the newsprint we see in your insulation, but certainly conventional cellulose loose fill or blown-in insulation that uses recycled newsprint or paper is treated with a fire retardant, often a borate salt, that also imparts some mold resistance.

On 2023-09-06 by Sam

@InspectApedia Publisher, thank you so much for your reply and help! My GC just informed me it’s supposed to be Thermafiber insul-fill.

Here’s an image of what it looked like when wet. Thoughts?

On 2023-09-02 by InspectApedia Publisher (mod)

@Sam,

From your photo and description that is certainly not 100% mineral wool insulation - bits of paper are characteristic of cellulose insulation

See CELLULOSE LOOSE FILL INSULATION for details. https://inspectapedia.com/insulation/Cellulose_Insulation.php

Find and post a photo of the packaging - if there is any - of the insulation product used by your installer - else ask them to tell you the product name and brand - then we can together look at the product specification. IT looks as if you have a mix of at least two insulating materials.

I don't assume that you've been "hosed" (before we know the product specifics we don't even know its actual cost ) and I don't assume the material installed is not perfectly fine, but I, too, would want to know what was installed and I'd be disappointed if I were misled by the installer.

On 2023-09-02 by Sam

Hi. I had what was supposed to be 100% mineral wool insulation blown into my ceiling cavities while renovating my home in 2021. Also, the vendor claimed their products do not contain formaldehyde.

Fast forward and I recently had a plumbing leak which required the removal of some of this now insulation and I was surprised to find lots of bits of paper in it and yellowish color mixed in. To me, this indicates the likelihood of formaldehyde due to binder use and the product not being 100% mineral wool.

Also, the product was sold to me as being resistant to fungal growth, but I’m guessing that’s not the case if it has been cut with a bunch of paper.

What are your thoughts about this product based on the photo and my description? Have I likely been hosed by a contractor who was trying to save a buck? Thank you for your help!!

On 2023-07-07 by InspectApedia Publisher - clumps of loose fill asbestos as attic insulation is unusual

@Sam,

Yes, I saw the pink fiberglass too

It would be very unusual for someone to have clumps of loose fill asbestos and attic insulation and even more unusual for it to be on top of fiberglass.

If you simply look carefully at the photos in this article series including click to enlarge them to see a larger sharper close-up example of mineral wool or rockwool and compare that with a large sharp close up and focus photo of your insulation most likely you will be completely convinced.

Perhaps you could take a very sharp up close photo showing the individual shiny fibers that characterize mineral wool.

On 2023-07-07 by Sam

@InspectApedia Publisher,

Appreciate your response. To my untrained eye, its hard to see the difference between the types of insulation. From my googling and reading here, the pink underneath looks like it could be fiberglass insulation, just not sure what the stuff on top is, maybe rock wool? This detached house was built in 1960 so asbestos was pretty prevalent then. This is all in the attic if that makes any difference.

What alarmed us was the vast difference in opinion from the experienced inspector vs the asbestos specialist. 90% vs 'most likely not/would be shocked'. The specialist told us it would cost us $600 for him to go check it out but advised against it since he doesn't think it is.

All this to say, i'm a first time home buyer so asbestos and all of these things are new to me so I'm just trying to make sure we know what we are buying. I will wait for the full inspection report to see if i could get some better photos. Does this look like fiberglass with some type of rock wool on top? Is that a normal combo for insulation? Thanks again!

On 2023-07-07 by InspectApedia Publisher - rock wool insulation not asbestos material

@Sam,

Compare your insulation to the rock wool insulation photos above on this page and also to chopped fiberglass photos in this article series.

Add to that some basic information needed to make a credible guess at insulation identification such as the building location and age.

That ought to make you pretty confident about the insulation in your home.

I'm surprised that an experienced home inspector would give a 90% sure guess that that insulation is asbestos - in fact, shocked. This might be a case of someone spending your money and everyone else's time as if those were endless and free since it doesn't cost him a dime to reduce his fear or risk.

See OTHER PEOPLE's MONEY

On 2023-07-07 by Sam

Looking to buy this home, the general inspector told us this looks like asbestos and he's 90% sure but said to consult a specialist. we called some specialists and sent them this photo and they said they would be 'shocked if it was asbestos'. Anyone know what this is or have any insight? Thanks

On 2023-06-18 by InspectApedia DF (mod)

@Danny H,

Thank you for that follow up.

On 2023-06-17 by Danny H

@InspectApedia Publisher, Thank you - the tests confirmed it's fiberglass, no asbestos.

On 2023-06-02 by InspectApedia Publisher - white fiberglass is not an asbestos product

@Danny H,

That looks like white fiberglass insulation.

Fiberglass is not an asbestos product.

On 2023-06-01 by Danny H

Insulation found in an old 1957 home. Any idea what this might be? Any chance it contains asbestos?

On 2022-12-28 by InspectApedia Publisher

@Philip W,

That looks like fiberglass or, less likely but possible, mineral wool.

On 2022-12-28 by Philip W

A roofer put his foot through the roof and through the ceiling of our apartment, and this insulation fell into the apartment. Trying to get an idea of chances that this contains asbestos. Thanks very much.

On 2022-11-22 by InspectApedia (mod)

@Robert,

That does look like rock wool and nothing appears concerning.

On 2022-11-22 by Robert

While removing insulation from my attic (housw built in 1929) I discovered a small patch of this loose white insulation. It appears to be rock wool but I am uncertain and concerned about any health hazards it might cause.

The pink fiberglass insulation that can be seen in the image is most likely from nearby newer insulation but could also be part of this loose white insulation too. I have only moved it while wearing a mask and gloves, and then only lightly moving it aside. Does anything in this image appear concerning?

Very much appreciate your kind attention to this matter!

On 2022-07-25 y InspectApedia-911 (mod)

@Rob,

Please use the on-page search box to find our article titled

OTHER PEOPLE'S MONEY

To understand what happens when you try to pin down someone to give you life safety or significant financial advice when they have very little information and have already told you what they think. You'll see that the result is people will spend your money to avoid their own risk.

On 2022-07-25 by Rob

@InspectApedia-911, Would this be something that you would recommend getting tested? Need to run some new wire 🤔

On 2022-07-24 by InspectApedia-911 (mod) - fiberglass put over mineral wool insulation

@Rob,

That does look as if some loose-fill fiberglass was put atop some older mineral wool or rock wool.

Take a look at

MINERAL WOOL / STONE WOOL ASBESTOS CONTENT

https://inspectapedia.com/insulation/Mineral-Wool-Asbestos.php

On 2022-07-24 by Rob

I bought a townhouse in Ontario and am looking at doing some work In the attic, there seems to be 2 kinds of insulation. I've be "told" that neither would contain esbestos. Opinions?

On 2022-04-27 by Inspectapedia Com Moderator - dirty rock wool insulation

@Jake,

You are on exactly the right page for that insulation. Please take a look at some of the example photos above.

On 2022-04-27 by Jake

What kind of insulation is this?

On 2023-03-16 by Marc

@InspectApedia Editor , Great, thank you. From your pictures that is what I thought, but thank you for validating.

On 2023-03-16 by InspectApedia Editor - mineral wool insulation

@Marc,

That looks like mineral wool insulation.

See

IDENTIFICATION OF ROCK WOOL, MINERAL WOOL BUILDING INSULATION (this is the page you are now on)

where we will eventually move your question and photo to be a part of that article.

[This reader comment and our reply were originally posted on a different unrelated page.]

On 2023-03-16 by Marc

Can you help identify this insulation type. Thank you

On 2022-03-02 by Inspectapedia Com Moderator (mod) - pink fibrous insulation - not asbestos - not rock-wool

@Nick,

The presence of that little fragment of pink fibrous insulation atop a big clump of white fibrous insulation suggests we're seeing either all chopped fiberglass or a mix of fiberglass and mineral wool insulation.

On 2022-03-02 by Nick

Hello I was cleaning out my walk in closet, and my attic cover for some reason fell onto my foot the entire trim came off messed up my foot pretty bad, so I didn't notice the insulation that was all over me and my closet right away.

I doubt it's anything serious it looks like rockwool or mineral from the pictures in this article and other comments but I thought I'd ask just to put my mind at ease. It's soft and fluffy and makes my fingers itchy/ numb when I touch/ pull it apart.

Thanks so much for your time

On 2022-01-31 by Inspectapedia Com Moderator (mod) - Rock wool identification where cat ran wild in the attic

@Ian,

Yes, that's rock wool.

My cat Harry did the same thing.

So glad we could help.

On 2022-01-30 by Ian - my cat fell into the attic insulation and ran amok - 1922 Sears Kit House

Hi. my cat snuck into my attic crawlspace today and slipped into a gap and got stuck running amok in the space under the floor. We tore up the attic to get her out, making a mess an spreading around insulation.

Given that the house is a 100 year old Sears kit, i was panicked about asbestos. after a long search on how to identify it I came to this site and it's the only one that has reliably shown examples of different insulations and provided actionable descriptions.

Really appreciate it...I am now 95% sure I have rock wool and i dont feel so worried.

Thanks!

On 2022-01-23 by Inspectapedia Com Moderator (mod)

@Cyd Robb,

For this insulation, compare to our photos of Vermiculite - taking a closer look - VERMICULITE INSULATION


and if you agree that yours is vermiculite (your photo lacks close-up detail that would let me conclude that but that's a reasonable guess)
then
see

WHICH VERMICULITE PRODUCTS CONTAIN ASBESTOS ? https://inspectapedia.com/insulation/Vermiculite_Insulation.php#VermicAsbes

On 2022-01-23 by Inspectapedia Com Moderator (mod) - what is this brown insulation?

@Cyd Robb,

Compare the insulation in your photo to the mineral wool photos on this page.

Then see HOW TO IDENTIFY VERMICULITE INSULATION for your "termite poop" insulation ID

On 2022-01-23 by Cyd Robb

He also found this material in one heap. He said it resembled termite poop, but wasn't. No sign of termite damage. Thank you for your help.

Hello! My husband found this blown in insulation in our attic. Our house was built in the 1950s.

Concerned it may have asbestos. Thank you in advance.

On 2021-05-05 by danjoefriedman (mod)

@Rick,

No, rather they meant that the insulation does not itself tend to absorb water;

However it's good practice to install a vapor barrier on the warm side of a Quebec home's exterior walls. That's because air leaks and thus moisture leaks into wall cavities can cause condensation and accumulation of water on cooler surfaces such as on the wall cavity side of exterior wall sheathing; ultimately that invites mold contamination or insect attack.

I add that the vapor barrier is not as critical as we used to think: research has shown that the worst air-leakage into and out of wall cavities occurs at the penetrations such as around electrical receptacles, switches, light fixtures, etc.

Still, I'd do it if my home's walls were open;

Also important: seal around those openings into the walls or ceilings.

For your second question please see ASBESTOS IN MINERAL WOOL / STONE WOOL

Further comments, criticism, suggestions, questions are, of course, always welcome here.

On 2021-05-05 by Rick

I have John Manville Type A waterproof blown insulation made in Quebec in my house. It was blown in. Cannot find ant reference to this material . Does waterproof mean I don’t need to install vapour barrier now that I have removed plaster from the walls? Also does it contain asbestos? Unknown when it was blown in?

On 2021-04-10 by danjoefriedman (mod) - looks like mineral wool or rockwool insulation

@Eric, that looks like mineral wool or rockwool insulation but honestly the photo isn't quite clear: please post a sharp photo from a bit closer.

On 2021-04-10 by Eric

Hi,
Can you tell what type of insulation this is? It is from inside a wall of a 1942 house in Minneapolis. Thanks in advance for any info!

On 2021-01-18 by danjoefriedman (mod)

Apologies but from the photo I can't tell for sure. Usually mineral wool in residential buildings is a loose fill material but it might be that your installer found a mineral wool blanket.

Certainly is either mineral wool or fiberglass.

On 2021-01-17 by Rich

Hi,

Is the grey looking insulation in this picture mineral wool? It’s a few inches thick, and for the most part looks like it’s been put in my loft in rolls over the top of other insulation be the previous owners.

On 2018-12-29 by danjoefriedman (mod) - which is better: mineral wool or fiberglass

I don't think there is an objective right a wrong answer to your question although there may be specific advantages in one building insulation area shape or ease of application between the two products. Compare cost and R-value.

On 2018-12-28 by nancy brannen

Which of these two products (blown-in mineral wool balls VS blown-in fiberglass) is a better PRIMARY insulation?

On 2021-02-02 by (mod) - don't confuse mineral wool or rock wool with vermiculite insulation

Coleman, thank you for the photos of Sears Best "Mineral Fill" insulation, and your photo of Sears Homart Pellet Type Rock Wool Insulation - we will certainly keep these with this article series.

Typically national brands like Sears contracted to buy their materials from more than one supplier, depending on availability and price; so it is possible that **IF** you have vermiculite insulation sold by Sears, that least some Sears vermiculite came from the Libby mine; until I can find more specific details it would be prudent to treat the Sears Vermiculite as presumed to contain asbestos.

Really? Well not quite. Both of your packages describe insulation that may not be vermiculite at all but rather mineral wool or rock wool.

Certainly the Sears Pellet Type Rock Wool is likely to be mineral wool not vermiculite, and

Your Sears Roebuck Best of All Insulation package labeling describes the product as "Mineral Fill" - that may be mineral wool, too.

Please post a photo of what the actual insulation itself looks like so that we can confirm what it is.

Rock Wool or mineral wool insulation is not a vermiculite product.

See details at MINERAL WOOL APPEARANCE VARIATIONS

On 2021-02-02 by coleman - photo of Sears Best of All Mineral Fill Insulation

Here is the Sears best of all insulation bag [ shown above ]

This Q&A and these photos of Sears Roebuck insulation packaging were posted originally

at VERMICULITE INSULATION

On 2021-02-02 by coleman - Photo of Sears Homart Pellet Type Rock Wool Insulation

I can't find ANY information on vermiculite from Homart and Sears (best of all insulation) I found 2 bags in my attic and will be sending it out for a test but was trying to find some product info in the meantime.

I'm attaching pics if anyone has information it would be greatly appreciated

On 2021-01-18 - by (mod) -

Apologies but from the photo I can't tell for sure. Usually mineral wool in residential buildings is a loose fill material but it might be that your installer found a mineral wool blanket. Certainly is either mineral wool or fiberglass.

Certainly the bright yellow fibrous insulation in part of your photo is fiberglass, not mineral wool or rock wool.

On 2021-01-17 by Rich

Hi,

Is the grey looking insulation in this picture mineral wool? It’s a few inches thick, and for the most part looks like it’s been put in my loft in rolls over the top of other insulation be the previous owners.

On 2018-12-29 by (mod) - which is better: fiberglass or mineral wool for primary insulation

I don't think there is an objective right a wrong answer to your question although there may be specific advantages in one building insulation area shape or ease of application between the two products. Compare cost and R-value.

Take a look at INSULATION R-VALUES & PROPERTIES where you can compare the insulating values of those two options (along with many other materials)

On 2018-12-28 by nancy brannen

Which of these two products (blown-in mineral wool balls VS blown-in fiberglass) is a better PRIMARY insulation?

...

Continue reading at MINERAL WOOL by MICROSCOPE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• ASBESTOS-FREE INSULATION MATERIALS
• ASBESTOS INSULATION
• BALSAM WOOL BATT INSULATION - a cellulose product, not a mineral fiber
• FIBERGLASS INSULATION IDENTIFICATION & PROPERTIES - home
• INSULATION IDENTIFICATION GUIDE - home
• MINERAL WOOL - ROCK WOOL INSULATION
  • MINERAL WOOL / ROCK WOOL DEFINITIONS
  • MINERAL WOOL / "Rock Wool" COMPOSITION
  • MINERAL WOOL / STONE WOOL ASBESTOS CONTENT
  • MINERAL WOOL APPEARANCE VARIATIONS
  • MINERAL / SLAG WOOL AIRBORNE PARTICLES
  • MINERAL / ROCK WOOL INSTALLATION, SETTLING
  • MINERAL WOOL / STONE WOOL R-VALUES
  • MINERAL or SLAG WOOL HEALTH EFFECTS
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