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Community and Q&A

Roxul Comfortboard for Exterior Sheathing

KeithH | Posted in Green Products and Materials on

Hi all,

I’m wondering if anyone has priced or used Roxul Comfortboard for exterior sheathing recently. Now that I can source this material in my area (Rockies USA), I’m interested in using this product for a project but am finding the pricing a bit deterring. I threw together a little R per buck spreadsheet for ready to order pricing (off shelf and big box pro desk). I was expecting a 20% to 40% premium for comfortboard but instead found pricing in the neighborhood of triple the cost per R per sf of foamboard of any type (depending a bit on your polyiso deration swag). 3″ Comfortboard appears to be running (4/21/2016) $42 a sheet.

So that begs the green building question? Is there an alternate sourcing folks have used? Is this really the price of the material? I’m a little surprised that 3x greater R cost is tolerated by the market.


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  1. KeithH | | #1

    Should have said 3' x 4' sheet for the comfortboard pricing. $42 a 4x8 sheet would be reasonably competitive with XPS.

  2. Expert Member
    Dana Dorsett | | #2

    What size sheets?

  3. Expert Member
    Dana Dorsett | | #3

    At 29 cents per R-foot^2 that's quite a premium (up there with 3lb spray polyurethane)!

    I haven't priced it locally recently, but IIRC it was running about 20 cents/R-ft^2 in my area last year- "only" ~2x the cost of EPS or polyiso, and only slightly more than 2lb polyurethane.

  4. GBA Editor
    Martin Holladay | | #4

    If you can find a good source of recycled rigid foam, that may be your best bet. It's even cheaper than new rigid foam -- and therefore far cheaper than mineral wool -- and it keeps the rigid foam out of the landfill (at least for the next 50 to 100 years).

    1. alexdorf | | #23

      Is there a solid source for buying recycled rigid foam, seems like a win-win.

      Also, just read your Energy Nerd book -- amazon review to follow ;)

  5. KeithH | | #5

    Yeah, that was my reaction. I'm a comfortbatt fanboy and think the premium can pay for itself in superior installation and ease of installation but the premium over fiberglass batts is much more modest. With the comfortboard, however, I think the cost will be increased from a labor and install perspective compared to foam.

  6. JC72 | | #6

    A friend of mine living in Toronto says that single family dwellings are incredibly expensive to build in Canada so I suspect Roxul tends to add some a bit of 'premium product' to their pricing strategy.

    Then again foam, unlike mineral wool, is basically a derivative of oil and very light to transport.

  7. KeithH | | #7


    I believe that Roxul is producing all the USA product stream in Mississippi now. Mineral wool isn't nearly heavy enough for transportation inside the USA to be a relevant cost.

  8. DIYJester | | #8

    I would have them double check their pricing. The Big Box store I dealt with tried to raise the price like that one time by selling it per piece for the 2" version. I called Roxul and they said it was sold in 3 piece packages and the cost was probably incorrect. After a bit more pushing with the retailer they realized that they were incorrect on the pricing and it was back to about the same as 2" XPS.

  9. KeithH | | #9

    Mike, you might be onto something. I'll review.

  10. user-626934 | | #10


    The sheets are 2'x4', not 3'x4.

    It's likely that the price is supposed to be something like $42 PER BAG (3x 2'x4' sheets per bag). Here's an online source that has the per bag price for 3" Comfortboard IS at $50 per bag -

    Home Depot Canada sells 1.5" product (6 sheets per bag) for ~$57 (Canadian $)...~$45(US).

    Most projects would probably be better off using Roxul's Rockboard 80 product from their "commercial" line....same 8lb/ft3 density as the "residential" Comfortboard IS product, but ~1/3 less expensive, at least in my area (Virginia).

    Also, it's interesting to note that on Roxul's website, the residential rigid board product is now called "Comfortboard 80" longer "Comfortboard IS" -

  11. KeithH | | #11

    Thanks John. I appreciate all the 'that does sound wrong' feedback.

    I don't believe my region of HD sells the commercial products (can't get drainboard for example) so I'll probably have to stick to the residential product line.

  12. DIYJester | | #12

    I was able to try to order the Drainboard from the HD, but you have to buy it by the semi-load, about $17,000 worth. I used Comfortboard IS below grade to insulate my foundation wall and have not had any issues with durability.

  13. KeithH | | #13

    Thanks to the folks who chimed in: seems wrong.

    The way Big Orange prices things it won't be obvious to you or the likely not experienced with ComfortBoard pro deck associate that you are getting a quote for 3 bags of 3 pieces (9 pieces or 72 sf) which can lead to thinking the pricing is 3x expectation.

    Current Big Orange pricing is yielding a 100% markup over unfaced EPS or polyiso, 50% on XPS, and roughly similar to T&G XPS. As the saying goes, your mileage may vary.

  14. user-626934 | | #14


    I wasn't suggesting you source the product through Home Depot...I was just using their pricing as a reference point. I would call Roxul and find out who the closet 2 or 3 distributors of their commercial line are.

  15. DIYJester | | #15

    I just bought 16 packages of the 2" 3'x4' Comfortboard IS for about $43 a package (36 sq. ft.). This is only about 20% higher cost than XPS by me. Due to seeing subterranean termites withing 10 feet of my home, foam below grade was not an option.

    This was a simple order, wife called the desk, told them what we wanted, apparently it is now in their computers, and we were done. The past two orders I have made were a bit more difficult, and during the second order the associate was confused and tried to charge me ~$43 per piece, not package.

  16. user-6504396 | | #16

    A late post to this thread. I just got a quote for Comfortboard IS from a local supplier in Washington. The representative told me that Roxul no longer makes the Comfortboard IS and has replaced it with Comfortboard 110. His prices were $0.82/ft2 for 1", $1.65/ft2 for 2", and $1.73/ft2 for 3" I looked online and see that the comfortboard name reflects the density: 40, 60, 80, 110 for 4, 6, 8, and 11 lbs/ft3. I'm assuming the Comfortboard 80 is cheaper. Is there a significant difference between the 80 and the 110 in terms of how easy it is to apply?

  17. charlie_sullivan | | #17

    Kevin, Comfortboard IS is specified at 8 lbs/cu ft, so I think Comfortboard 80 is the equivalent. 110 would surely be stiffer and might be easier to deal with, but people report that 80 works fine.

  18. chimewind | | #18

    Just priced Comfortboard 80 from Home Depot in upper Midwest. Pallet of 3" thick R12 2ft. x 4ft. sheets (66 on a pallet) was $954 or $14.55 a sheet, $1.81 sq. ft., ~$0.15 sq.ft per R1 value. For 3" thick R12 3ft. x 4ft (32 on pallet) it was $699 or $21.85 a sheet, $1.82 sq. ft., ~0.15 sq.ft per R1 value.

    XPS: 1" thick R5 4ft. x 8ft. $12.32 a sheet, ~$0.39 sq.ft., ~$0.077 sq. ft. per R1 value.

    EPS: 2" thick R8 4ft. x 8ft. $11.25 a sheet, ~$0.35 sq. ft., $0.044 sq. ft. per R1 value

    Summary of $ per sq. ft. per R1 value from my local Home Depot:
    XPS: ~$0.077
    EPS: ~$0.044
    CB80: ~$0.15

    Of course each has advantages/disadvantages which make these price comparisons not completely fair. The comfortboard being basically fireproof is a big one.

  19. Yupster | | #19

    Just to throw further confusion into the bit about the name change, Roxul has been rebranded to Rockwool now. So it's not Roxul Comfortboard IS or 80 anymore, it's Rockwool Comfortboard 80... :D

  20. Expert Member
    Dana Dorsett | | #20

    At 15 cents per R-foot just for the material it's more expensive than the installed cost of 2lb closed cell spray polyurethane. Buck a foot R6 spray foam is 17 cents per R-foot, but it's the installed price.

    Similarly 35 cents per board foot open cell foam is about 9-10 cents per R-foot, installed price.

    I'm recommending spray foam here, just noting the comparative price points.

  21. jasonn1234 | | #21

    yes I also discovered the ridiculous cost difference up here in Canada between the rigid roxul and the batt roxul. See my other post where I then chose to put up regular Roxul R14 on the outside walls with 2z4 with foam backing to support the roxul batts

  22. danielolson80 | | #22

    Jason, I realize this is an old thread but I am interested in your approach of using the R14 Roxul batts on the exterior. I am thinking of trying something similar, using 3.5" R15 Thermafiber batts that I can get locally. The price seems to be far cheaper the prices in the discussion for Comfortboard 80. A pack that contains 24.5 ft^2 of the 3.5" material costs $18.19 at one big box store locally. Until recently, the same product could be had for around $13 a pack at another big box store, but for some reason they stopped carrying Thermafiber. But even at the higher price it works out to about $.05/ft^2/R. R23 batts, 5.5" thick, are also available.

    These batts are 4.0 pcf, I think, which I am sure has a lot to do with why they are cheaper than ComfortBoard 80. But if you had success working with similar material, lower density batts seems like a more efficient use of the material.

    I cannot locate your other post that explains your approach. If anyone can direct me to that post I'd appreciate it.

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