Thermafiber Insul-Fill
hydronick
| Posted in General Questions on
Do any of you have experience with owens-corning’s Thermafiber mineral blowing wool Insul-Fill. I want to use a blown in mineral wool but could not get a hold of granulated Rockwool in NY. I thought InsulFill would look similar but it doesn’t. I can’t find much online or in this forum about it. Menards sells it as well as my local insulation distributor. My distributor said he has a couple of pallets but nobody buys it. Is it not a good product or do people just not know about it?
Thanks
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I've been aware of loose fill (blown) mineral wool for years, but I've never seen anyone actually install the stuff. I think the reason for this is that mineral wool is much more expensive than fiberglass, and the primary advantage to mineral wool is it's easier to install the batts well, and it gets a bit more R per inch compared to fiberglass. In a loose fill installation, there is no difference in the ease of installation -- both blow in about the same, and there is usually no real advantage to more R per inch, since it's easy to just blow in a little thicker layer to hit your R value targets. Basically mineral wool doesn't really offer much in the way of advantages over fiberglass as a loose fill insulating material, but it does cost a lot more.
If you don't want to use the usual go-to of blown cellulose, I'd look at blown fiberglass instead. I've never really considered blown mineral wool on any project I've ever done, even though I prefer to use mineral wool batts anytime I'm working with a wall.
Bill
Thanks for the reply. Im specifically looking for anyone that has experience with or knowledge of Insul-Fill.
hydronick,
I think you'll be waiting for a while. To date, I don't know of a single instance where it's been installed.
I've used their mineral wool batts lots of times, with no issues (I actually like them better than some other brands, because they are firmer and easier to install). I doubt there would be any reason to expect problems with the loose fill version of their product, I just haven't ever used it myself or know of anyone who has. I think the only negative for that product is the cost, since it's more expensive than loose fill fiberglass. The only other potential negative I could think of is if it weighs more per unit R value than fiberglass (which it might) or cellulose (which I doubt), in which case ceiling loading with higher R values might be a concern (more potential for sagging ceilings).
I have been using more Johns Manville mineral wool batts as of late though, because the Thermafiber product seems to have gotten much harder to find in the last year or so. I don't know why that it is, but if the batts have gotten hard to find, there may well be issues with availability of the loose fill version of the material too.
Bill
Yes, thank you. My distributor has Insul-fill for surprisingly "cheap". I bought a couple of bags. It looks the same as white fiberglass blowing wool or like sheep wool. I was expecting to look the same as granulated Rockwool. Just as my supply guy and you both said no body seems to be using it. I found that odd and am wondering if I'm missing something and ignorant to what everyone else knows about this stuff and they aren't using it for a certain reason. I was hoping the wealth of knowledge here would have info about it. I'm worried that if nobody even here has knowledge of it I'm the only idiot buying it because I'm unaware of something everyone else knows.
I wouldn't worry about using the stuff. I've never heard of any problems with loose fill mineral wool, and I HAVE used Thermafiber batts and never had a problem with those. You'll probably be fine with the material you purchased, and if they gave it to you cheap, that cancels out the only real negative -- price -- I can think of that would make people not want to use that material.
Bill
There was a time when Steve Baczek was a big proponent of blown in mineral wool. However, i haven't seen much about it in his posting for a while.
https://www.finehomebuilding.com/project-guides/insulation/blown-mineral-wool-insulation?epik=dj0yJnU9VnF5bXMtQmJlemVLYzNnSzFia0Nmal8tVEJDT0tjRXomcD0wJm49LTN4WUNCUV9IcVRnbGU5UkFoLWQ1ZyZ0PUFBQUFBR1FLcU1v
https://buildshownetwork.com/contents/wool_insulation_january_2022
Thanks to all that replied. I would normally use batts but they wouldn't work in my situation. I needed to add insulation to a wall that has no top plate in the attic. It's a gable end wall that that abutts a converted loft with a cathedral ceiling. I may make another post about insulating the room since I've never seen a room like it and am at a loss on how I should handle it. I like the non combustible feature of mineral wool and use it normally as a plumber when fire stopping penetrations. I plan to pour the fill into the bays from the top to top off the old 1964 fiberglass spinsulation batts then cover the bays with blocking.
I have a fair amount of experience with mineral wool insulations. In my opinion mineral wool exceeds both fiberglass and celluloses capabilities in terms of fire resistance, water/moisture resistance, and R-value per inch.
Unfortunately, Owens Corning announced it is closing it’s Thermafiber Insul-fill operations in October 2023 with no plans to restart them. Rockwool has not sold loose fill mineral wool in the U.S. and Canada in at least 5 years.
Why is it being discontinued? In my mind it’s the cost of the product and the lack of public/ industry(installers) knowledge of mineral wool. Big fiberglass has a heck of a hold on the US and Canadian markets and trying to convert installers and the public alike to a different product is a monumental task. (even though mineral wool predates fiberglass!)
So what’s your solution? You have a couple options. 1, buy the mineral wool while you can! (Buy some extra and ship it to me too) this would be a great application for it. 2, you could use batts and layer them, not the best, but it’s hard to conceptualize the full space and the access you have. At very least I wouldn’t use cellulose because of it’s propensity to absorb moisture.
I hope this helps.
I'm curious how your project turned out here. I'm also looking for blown mineral wool insulation for a floor space that I'm trying to add some sound dampening to, but don't have good access to. I was surprised at how hard it seems to be to find. I emailed Rockwool about it and received the following response
> ROCKWOOL does not produce a loose fill insulation in North America. We only produce insulation in the form of compressible batts or rigid/semi-rigid boards. ROCKFILL was an import for a couple of years from Europe. It was a loose fill top up insulation for hand spreading. Note that Rockwool cannot be used in blown in machines. It’s too dense a material. It did not sell well in NA market and was discontinued in 2014.
I'm followed up because I'm confused by the claim that you can't use rockwool in blowers at all.
So now I'm looking to see if I can get my hands on insul-fill. Sounds like it may be tricky as well :-(
The loose fill versions of mineral wool are already shredded for the blowing machines, not bound together in batts the way the normal Rockwool mineral wool batts are.
If you want sound dampening and not thermal performance, cellulose is likely to actually work better, since it's denser (more mass). Mineral wool is better than fiberglass for the same reason, but cellulose is better than either of those materials for sound deadening.
Bill
Ah cellulose is denser than mineral wool? I had thought it was the reverse. I will go with cellulose then, thank you.
Cellulose is denser when dense packed compared to mineral wool. Loose filled cellulose is between fiberglass and mineral wool in terms of density (weight per square foot for a given thickness of material).
In practice though, cellulose provides pretty good sound deadening for walls. I haven’t tried it in a floor, but I would expect similar performance in a ceiling or floor as you’d get in a wall.
Bill
Got it. That makes more sense. I will use rockwool batts in the ceiling I have direct access to and then blow cellulose into the floor space I don't. Appreciate your advice!