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Community and Q&A

Purchasing Comfortboard 80 in the south east

Kyle Bentley | Posted in Project Management on

Hello All,

This is my first post on BGA, but I’ve gained so much from all of the discussions and articles that I’ve decided to take on a task myself.  Thanks to all of the members and moderators who’ve posted many great answers!

I’m from northern Alabama, and the short version is that I’m building a workshop.  I would prefer to use CB80 externally, between 5/8″ OSB with tyvec, in a normal rain screen configuration, leaving the studs bare until a later date.  One preference is the fire resistance, the other is termite control.  However,  I am finding it hard to source CB80 in this region, while XPS and to some degree PolyISO are abundant in the big box stores.  Every supplier I’ve called within ~50 miles can’t/wont get it.  I have found that I can order R6 CB80 in quantities of 20 packs from our local Lowes, but that’s the extent of what I’ve found.

Should I abandon the idea of CB80, and just stick to XPS?  Part of the reason I wanted to try the rigid mineral wool is so that I could evaluate its performance in this structure for a good few years before building my permanent home.  Does anyone know of a supplier in the Birmingham/Atlanta/Nashville triangle that carries it?  I feel that I must be overlooking something, or asking the wrong questions when I call suppliers, though I don’t see how providing the exact product name and quantity I need leaves much room for interpretation.

Thank you all so much for taking the time to help others learn!

Kyle

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Replies

  1. Steve Knapp CZ 3A Georgia | | #1

    Kyle,

    I don't have a source for you but would like to suggest checking out reclaimed rigid insulation. Foam from roofs and factory seconds are widely available and much more affordable than rock wool. Here is an article with more detail: https://www.greenbuildingadvisor.com/article/how-to-install-rigid-foam-sheathing

    1. Kyle Bentley | | #3

      Thanks Steve, That's good information.

  2. Expert Member
    Akos | | #2

    Check with comercial drywall suppliers. This is a standard item on commercial builds here, you might still need to order by the skid though if you need an oddball size.

    I generally stay away from rigid mineral wool. It is expensive and not the easiest to work with as it still slightly squishy. Takes a lot of adjustment to get your strapping flat. Critters won't eat it, but they will still happily live in it and chew up any wood behind it so you still have to detail everything to keep the critters out. At that point might as well use cheaper foam.

    1. Kyle Bentley | | #4

      I hadn't checked with any drywall suppliers, I'll try that next. I guess I was hoping that it would deter the critters enough to look towards my neighbors! I'll make provisions to treat the soil around the shed, and keep bait stations nearby.

      Based on what I've calculated, XPS is already ~50% of the cost of CB80 ($/R.ft^2). I am running out of easy reasons to keep pursuing mineral wool, I suppose I just want to be complete.

  3. John Clark | | #5

    https://www.rockwool.com/about/dealer-finder/

    Montgomery Wholesale Lumber Inc.
    RUSSELL BLDG. CTR.
    Capitol Materials
    FRIDAY LUMBER CO.

    1. Kyle Bentley | | #6

      Thanks John,

      I'd tried a few of those, with exception of Friday and Montgomery - they're further than I'd really want to drive. The other places carry comfortbatt, but no comfortboard.

  4. Russell Miller | | #7

    We have the same problem here. I'm hoping with a new Rockwool plant 30 minutes away that I'll have better access to their products.

  5. Bill Dickens | | #8

    My supplier in Portland OR was struggling to restock when I was looking for Comfortboard a few weeks ago. Lengthy delays due to cornavirus related supply chain issues. I ended up switching one wall of my tiny house project to XPS.
    If your schedule is not pressing then I suggest getting in your backorder - your supplier should be able to do this - otherwise switch to another material.
    BTW, my supplier was not listed on the Rockwool site. I tried one of the listed suppliers. They were not able to deliver the small quantity I needed but they referred me to a non-listed supplier that was excellent (aside from present supply issues.)

    1. user-7665631 | | #11

      Hi Bill, can I ask you your supplier was in Portland? Still very challenging to find the material now, 9 months after your post. It's kind of amazing that there isn't a competing product for CB. SL 960 has been around in town which has similar specs to CB 80 but isn't tested for use as exterior insulation. Wonder if suppliers are stocking it for fire-blocking or if people are trying to use that for exterior insulation.

  6. Andrew C | | #9

    I understand the frustration in trying to source materials that aren't in abundant supply at the local big box. However, I encourage you to try to find some mineral wool that works for you. Termites are a big deal, as are ants. If you think you're going to try building a home with it, this would be an ideal time to practice.
    Good luck and have fun with your project.

  7. Kyle Bentley | | #10

    All,

    I thought I'd provide an update -

    I was able to source just over 1000 sq. ft. through a company called Service Partners. The rep in the Birmingham office went very far out of his way to help me source it, and it is being shipped from a location in Boston to the Huntsville branch. The pricing wasn't as bad as I was expecting, just over $1100, or about 15-20% higher than XPS. That small premium is worth the experience to me.

    Thanks for all the advice, I'm certain I'll have more questions down the road.

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