GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Mineral wool concerns

doreendoreendoreen | Posted in General Questions on

deciding on a green solution to insulation. Live in southern New England – looking to move slightly north. 

Decided on  denim before discovering rock wool.  

was set to Purchase rock wool when I found this article stating it can be toxic.  
any thoughts / experience out there with either ?

thank you 

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Zephyr7 | | #1

    Someone always seems to think anything can be toxic. Mineral wool has a pretty good record so far, and it’s not new as implied in that article — its been around a long time, it just hasn’t been used for large scale insulation projects much. Mineral wool has been used as a fire stop material for decades. The arguments against the plant in Virginia had everything to do with emissions from the coal fired furnaces, which are no different from those of the many coal fired power plants in the region. You can debate the issues with coal emissions, but the point is the mineral wool plant doesn’t have any unique issues in that particular regard. The department of education isn’t a body that is going to know anything about anything industrial, either, so their concerns are likely from fear of the unknown and not any actual scientific knowledge.

    I don’t think mineral wool is any more or less dangerous than fiberglass. You absolutely want to wear a mask while working with it as you would when working with any other dusty product. Once the product has been installed though, the dust issue stops. You are enclosing the mineral wool inside of a wall after all, and the wall itself is usually a pretty good air barrier which means it will block the migration of any particulates (dust) that may come from the mineral wool.

    Personally I’m not a fan of most organic insulation materials due to them being more likely to harbor pests or grow mold, both of which most certainly ARE potential health risks. Remember that health risk concerns are really all relative, since EVERYTHING has some potential risk. What you need to always think is “is A any more or less risky than B, because I HAVE to use one of them”. Chemotherapy drugs are dangerous and can kill you, but so can the cancer that they treat. Which is more likely to kill you? Usually the cancer, so the relative risk of the drugs is lower than the disease, so you take the drugs because overall that is the lowest risk situation. If more people would think this way about things, there’d be less fear and panic out there.


  2. Robert Opaluch | | #2

    I don't believe this "report" reflects our general consensus about Roxul's ComfortBatt, ComfortBoard or SafeNSound mineral wool products. They have no or possibly minimal threat to installers. Homeowners would have no realistic health threat since the products are imbedded inside walls, and they don't outgas. Earlier versions that contained some formaldehyde have been discontinued. Labeling these products "toxic" appears to me to be a dishonest over-reaction. Yes the production of these products apparently requires high temps and generates pollution around the WVA plant. However I personally find it absurd that the state that touts coal usage and mining would complain about much greener mineral wool products. I believe their argument is that the plant is located in a nice area and they would prefer it be located in someone else's back yard.

    I believe there are more realistic concerns about the use of closed cell spray foam and XPS foam board, which have high global warming potential. EPS/GPS/polyiso foam boards and cellulose/fiberglass/mineral wool alternatives that are safer and equally effective insulation choices. There are some concerns about the ichy fiberglass batts, and some warnings to wear protection to avoid inhaling the glass fibers. However, comparing it or mineral wool to asbestos seems inappropriate since the cancer-causing potential of asbestos is well-documented.

    I don't know much about denim insulation but the material makes great pants! :-) I believe its a rather pricey choice, probably in part because its not manufactured in such high volumes compared to fiberglass and mineral wool.

  3. Walter Ahlgrim | | #3

    Why is cellulose off your list? Given its low cost and high percentage of post consumer recycled content and long safety record.

    Please do not be offended by the question I just wanted to understand your thinking.


    1. Robert Opaluch | | #4


      I can't speak for doreen, but here's three reasons I would have for not using cellulose in certain situations myself:
      1. As a chronic do-it-yourselfer, I can't dense-pack cellulose. I can install batts and board insulation easily and well enough.
      2. If cellulose is not dense packed, its not as high R-value/inch as mineral wool or high density fiberglass.

      However for the reasons you cited, I've used it for ceiling insulation and for stuffing into existing walls (renovation). Its easier to blow into cavities then re-seal the wall than open up the wall for batts.

      I'd also add cellulose's good sound-deadening qualities as a plus, and mineral wool products also have this advantage.

      1. Expert Member
        Michael Maines | | #5

        Robert, the R/inch of cellulose actually goes down the more densely it's packed, from about R-3.5 or 3.6/in dense-packed to R-3.7-3.8/in loose-blown. Either way, less than mineral wool, which is around R-4/in.

  4. CarsonB | | #6

    To add my 2 cents to the chorus, the article linked is highly suspect. They say:

    "There are clear health concerns and it is difficult to imagine that policymakers will allow the material to continue to be used by construction workers and homeowners."

    Yet offer no actual cases or known issues are stated from mineral wool exposure, only vague and unsupported comparisons to asbestos; that statement is therefore, quite frankly, ridiculous. Don't be fooled by a quote from a doctor who offers no facts or citations. There were many documented cases of asbestos and hundreds of thousands of deaths linked to asbestos, so why can't they point to a single one for such a widely used material used for decades? Furthermore, some of the things they state are demonstrably false. It was used well before asbestos was banned, so it could not be developed as a replacement as they claim. Other fibrous materials such as fiberglass have been around as well and became the dominant insulation material, likely due to cost. Wear a mask, long sleeve shirt, and gloves, and you should be just as fine installing this as the thousands of people that do every day.

  5. John Clark | | #7

    An opinion piece which should be ignored full stop.

  6. 1910duplex | | #8

    We put rockwool batts (roxul) up in our attic rafters, and since we live in an old house, almost none of our rafter bays were the standard width, so there was LOTS of cutting into the batts to get them to fit. Even with all that mess, we had no problems with installation or afterward (we use our attic for storage). Wear long sleeve shirt, mask, gloves, and it's fine. (Recommend n95 construction mask rather than just a dust mask). No offgassing/smell, either (which I cannot say for spray foam).

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |