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Comfort Board 80 vs 110 – density worth extra cost?

Chris Armstrong | Posted in Green Products and Materials on

For our upcoming house build using 4″ of rigid mineral wool we have been quoted for both Roxul comfort board 80 and 110. Over the top of this we will install 2×4 furring and cedar siding.

The 110 has a compressive strength of 1120 PSF at 10% deflection, the 80 is only 439 PSF at 10%, using the 110 will simplify the installation of furring as it will compress less, but I don’t know that the furring installation sub would price their install any differently between the two products. (Furring install not by insulation contractor).

The cost difference is about $2,600. Is the potential for simplified furring installation worth the added cost?

p.s. GBA – The catpcha’s appear to be case sensitive, it would help if the users were made aware of this.

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Chris,
    I don't have an answer to your question, but I'm guessing that some GBA readers who have installed mineral wool on the exterior side of wall sheathing will post their opinions here.

    In the meantime, I'll provide links to relevant articles, in case you missed them:

    Installing Mineral Wool Insulation Over Exterior Wall Sheathing

    Installing Roxul Mineral Wool on Exterior Walls

    Wrapping an Older House with Rock Wool Insulation

    (And thanks for your suggestion on the CAPTCHA hurdle -- we're looking into it.)

  2. Jamie B | | #2

    Hi Chris,

    I am also wondering this as I'm getting ready to install my facade.

    What was your experience like? did you go with the 80 or the 110? Any advice or tips?

    Thanks,

    Jamie

  3. Sean Wiens | | #3

    The ComfortBoard 80 works just fine and you probably do not need 2x4 furring strips. I am putting on 6" of CB80 on using 3/4"x2.5" strapping. Yes, you can over compress if you are sloppy, but some compression is actually your friend as it allows you to true up any variances in the framing. The bigger issue is hitting the studs through a thick exterior layer. I discuss this at length on my project journal http://www.theEnclosure.ca

  4. Jonathan Lawrence CZ 4A New Jersey | | #4

    Chris,

    I agree with Sean that the ComfortBoard 80 should be just fine. I am using it now and you really have to overdrive it to get uneven compression. I was debating between 80 and the 110 myself, but after speaking with a Roxul rep who installed the 80 on his own house and told me the 110 would be overkill, I decided to go with the 80. As far as your furring size, that will be be dictated by your cladding's nailing requirements. My cladding requires a net nail penetration into the stud of 1 7/16", so I have to use 2x furring. The furring fastener size is then determined based on the assembly weight. The larger cladding companies like Hardie and LP can usually give you the fastener and furring requirements if you call their technical support. I spent hours going through the technical docs and ICC-ES reports to figure out what I needed. I then decided to call the manufacture up and explain what I was doing and they knew exactly what I needed and confirmed my calculations were correct. In hindsight, I just should have called first.

  5. Expert Member
    Malcolm Taylor | | #6

    Sean,

    The illustrated guides being put out by BC Housing are great. The way they have supported their building code changes and best practices should be a model for other jurisdictions.

  6. Sean Wiens | | #7

    Ya except my municipality has not accepted or even become familiar with the contents of the guide. They have forced me to have engineering sign-off. I of course contacted RDH (authors of guide) and am now waiting for their approval before I can proceed on my envelope. Has been very frustrating!

  7. Jonathan Lawrence CZ 4A New Jersey | | #8

    Sean,

    Thanks for posting that guide. That will make it lot easier for me trying to explain these assemblies to my subs.

  8. Expert Member
    Malcolm Taylor | | #9

    Sean,

    That's too bad. My building inspector shoves the guides at me whenever I see him. There is a rack with most of them at his office too. I've spent a fair amount of time here on GBA defending our building inspection system here in BC, but I'm beginning to suspect I've just been lucky to have had several really good BI's where I live.

  9. Sean Wiens | | #10

    A follow up on this. I purchased some ComfortBoard 110 that I am using for my sub floor slab application. I definitely do not feel this would be suitable for a wall application. It is TOO stiff. You really need some give in the product for ensuring your furring strips plane out when installing over wood framing. The ComfortBoard 80 is great for this.

  10. P2018 | | #11

    Check out PowerWool Rigiboard. About twice as rigid as Comfortboard 80 but below Comfortboard 110. Available at most building supply yards in BC and areas of Canada from http://www.power-house.ca

    1. qofmiwok | | #12

      2 years later, but can't find this stuff for sale anywhere through google. Is it still being made?

      1. P2018 | | #13

        Yes, two years later but it can be found at http://www.warehoos.com or the manufacturer's website http://www.powerwoolinsulation.com

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