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Community and Q&A

Dense pack cellulose vs mineral wool

Jeremy Henn | Posted in Energy Efficiency and Durability on

All I keep hearing and reading is about dense pack cellulose for wall insulation, yet rarely hear about using rockwool insulation.  The problem I have with dense pack cellulose is that someone like me can’t get there hands on a strong enough system to blow in dense pack.  So I’m trying to figure out why is hardly anyone talking about using rockwool.  It’s DIY friendly as well as being fire resistant and water resistant.  IS the cost of Rockwool versus hiring someone to come and blow in cellulose that big of a difference?  What are the drawbacks to using Rockwool?

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Replies

  1. Expert Member
    Rick Evans | | #1

    Hi Jeremy,

    Mineral Wool is a great product for all of the reasons you described. For a DIY approach, batt insulation is the way to go. Even if you could find a powerful blower, I would still avoid it and just stick with batts. Insulation blowers are heavy and you'll need two people- one to feed the insulation into the hopper and one to work the hose.

    If you are hiring somebody then I would opt for blown-in insulation like cellulose. Batts are hard to install correctly. It looks easy but achieving a Grade I installation requires care and precision. Blown-in insulation achieves a Grade I installation easily.

    Despite the benefits of Mineral Wool- it does have quite a bit of embodied energy compared to cellulose. This is another reason that green builders prefer cellulose. Cellulose also has moisture -buffering properties, increased thermal mass, and superior air-infiltration qualities when compared to Mineral Wool. Mineral Wool has a higher R-value.

    It may be worth getting quotes for dp cellulose though as the material + labor may still be less money than DIY mineral wool install.

  2. Expert Member
    Malcolm Taylor | | #2

    Jeremy,

    A lot of the talk about cellulose insulation here comes from two things: It performs better in very thick walls which benefit from moisture buffering, and it is more environmentally benign.

    You don't hear as much about mineral wool batts because the premium you pay for them over fiberglass isn't seen by most builders are being justified by their superior performance.

  3. Wooba Goobaa | | #3

    Steve Bazcek's views ... https://www.finehomebuilding.com/2018/09/14/blown-mineral-wool-insulation.

    I'm pricing blown mineral wool + smart vapor barrier for a MA reno of a 1910 build where the exterior clapboards / tar paper / sheathing will remain, interior plaster and lath removed. My goal is to insure any water or vapor that gets into the wall from the outside will not wet the insulation and will be able to dry to the inside.

    1. Expert Member
      Malcolm Taylor | | #4

      WG,

      I'm a bit confused. Cellulose gets dense-packed in walls (as opposed to loose-filled in roofs) so that it doesn't settle. The article says that blown mineral wool is heavier that cellulose, but doesn't need dense-packing. Do you know why that would be?

  4. Jeremy Henn | | #5

    Thanks Rick & Malcolm for the info. I will definitely look into pricing out the cost of hiring someone to blow in cellulose versus me putting in rockwool myself.

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