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Green Building Curmudgeon

The Green Police: Product Retrospective (volume 2)

More reflections from Carl Seville and Michael Anschel on some of the emerging green building products of the early 2000s

The Green Police check out Rockwool, formerly known as Roxul

Welcome to round two of my product retrospective, where green remodeler Michael Anschel of Minneapolis-based OA Design+Build+Architecture and I look back at our illustrious career as screen stars in the Green Police video series we made for The Journal of Light Construction and Hanley Wood a few years ago.

The idea of these posts is to take a look back at the products we covered, which were mostly new and innovative at the time, to see if they lived up to their promise. We’re also putting ourselves on the spot, as we see if we made accurate predictions about how the products would do in the competitive market of green building materials.

Ultimately, we hope this is yet another way to steer people towards innovative products to use in their projects and share our caution when we think something is dubious. If you’d like a more thorough introduction or just want to check out the products that we covered in the first round of this retrospective, you can find it here. Now, on to another round of products…

Slow and steady

While they still don’t have the market share of their competitors, some of the products that we were interested in when we made the Green Police videos have made slow and steady inroads with green builders. Minisplit heat pumps and mineral wool insulation are two products that fall into this category.

We’ve both always liked minisplit HVAC technology and it is encouraging to see it continue to expand in marketplace. I would like to see it used more in multifamily projects where the smallest available standard HVAC equipment is typically significantly oversized for most apartments. However, I understand that this is not an inexpensive technology and first costs often rule the day.

Michael pulled some weird scam and got minisplits installed in his house for free because he was supposedly in an airport flight path and they allow him to keep his windows closed in the summertime to cut the noise. I had to actually pay for them for my house, and even did a video for Mitsubishi about it.

Rockwool (Formerly known as Roxul), a mineral fiber insulation, is another product that we liked back in the day and still do today. Roxul has captured a modest share of the high-performance market, particularly for those who are interested in alternatives to foam products, for one reason, because it does not contain any fire retardants. Moreover, it doesn’t absorb water and is vapor-open. Although still a relatively small player compared to the various types of rigid foam and other types of batts, its use continues to expand in the industry (note that fiberglass batts are still the number one insulation used industry-wide). Watch the video until the end where Michael finally gets what he deserves!

Verdict: We still like minisplit heatign and cooling technology and mineral wool insulation; they are still around, and continue to grow their market share.

Keeps on rolling

Icycnene was one of the early open-cell spray foam companies. I used it in a lot when I started doing green renovation work about 20 years ago (yes Michael, I know I’m old), and it made incredible improvements in building performance. In new construction, I have come to the conclusion that spray foam can be an excuse for a weak or overly complicated design and while a very well performing product, almost any insulation installed properly can achieve comparable results, sometimes at lower cost. Michael, he of the frozen north, however is a strong proponent of using this spray foam insulation.

Verdict: A solid product that isn’t going anywhere, even if Carl might want it to be used less.

Not sure about this one

When Owens Corning had a robust building science department, staffed by some industry giants, they promoted all manner of interesting systems and techniques. Cavity Complete was one, a high performance, durable wall system design using multiple manufacturer’s products in an engineered assembly. It still has some life on the internet—the website has specs, architectural drawings, installation instructions, a 10 year  (limited) materials and replacement warranty, and details of an in-field quality assurance program aligned with the Air Barrier Association of America (ABAA), but I am not clear exactly who is doing what with it. I emailed the contact on their website for more info, but never got a response. It’s still a great blueprint for a wall.

Verdict: We still like it but without Owens Corning’s ongoing support it won’t gain traction.

Please, please use these

This is still a head scratcher. Why more people don’t use ventilated rainscreens on their walls is beyond us. I guess it’s because they aren’t granite counters–you can’t show them off to your friends (unless you are serous building geeks like us). Adding a rainscreen to your assembly adds cost issue for sure, but it is a small fraction of the cost of a building and will certainly improve moisture management and extend the life of exterior materials and finishes. Michael is continually frustrated by folks who overcomplicate the concept by installing wood furring strips around the home. Just use a dang matt already! Sheesh…

Verdict: We are evangelists for rainscreens but in residential construction they still struggle for widespread adoption. We still believe and have hope.

Prediction: They will become part of the building codes along with effective R-value calculations (Thank you Canada)

-Carl Seville is a green builder, educator, and consultant on sustainability to the residential construction industry. After a 25-year career in the remodeling industry, he and a partner founded a company, SK Collaborative. Photos courtesy of the author.


  1. Expert Member
    Dana Dorsett | | #1

    The Owens Corning wall system vidi the statement was made that the Foamular has a 90 year warranty to not lose it's R-value, which isn't exactly what the warranty states. The fine print says something different. ( It's important to read the fine print?)

    The warranty is for only performance to 90% of the labeled-R, not the full labeled R. That R5/inch is really only R4.5/inch, and to collect on the warranty claim it can't be buried or submerged, and the sample needs to be independently tested by a qualified third party.

    So how many warranty claims to THEY expect to actually be filed even if it happens to be performing at only R4.2/inch after 30 years?

    Exactly zero, sez me.

    From a wall system design point of view assuming anything more than R4.5/inch would be optimistic at best. Assuming (the fully-depleted) R4.2/inch would be perhaps conservative, but not insane.

    1. Expert Member
      CARL SEVILLE | | #8

      I'm sure their attorneys told them they would never have to pay a claim. It was a marketing plan that wasn't successful not a warranty.

  2. Expert Member

    Good blog!

    Michael needs to get out more though. Battens are cheaper, easier to install and yield a much better rain-screen than proprietary mesh. In areas like coastal BC where rain-screens are mandated in the code, you don't see mesh except behind siding that can't be easily installed over battens. There are good reasons for that.

    1. GBA Editor
      Brian Pontolilo | | #3

      I'd be interested to hear his thoughts on that too.

    2. JC72 | | #4

      Perhaps, but would you agree that it's much easier to get production builders on board with product which can be applied with the ease/speed of Tyvek? In the SE US, where Carl resides, for the past 20 yrs or so something like 85 percent of the housing stock was built by production builders.

      1. Expert Member
        MALCOLM TAYLOR | | #5


        Production builders here all use battens, both on houses and large multi-family projects. If mesh affected their bottom line, they would be the first to switch.

        1. JC72 | | #6

          Ya. I'm not seeing it in the good 'ol South. Hell, builders here still insist on installing HVAC equipment in vented attics.

          1. Expert Member
            CARL SEVILLE | | #9

            Rainscreens are very rare in the south, and multifamily projects I see almost everywhere. An occasional high performance single family builder might have one.

        2. Expert Member
          Dana Dorsett | | #7


          In your area rainscreens are required by code, and production builders HAVE to find the lowest cost options. There is no location that I'm aware of in the US where rainscreens are similarly required by code. In most of the US designers, builders, & crews don't have much of a clue as to what works/doesn't-work or even how to install battens correctly.

          I understand that in western B.C. pre-made battens ripped from 3/8" or 1/2" plywood at a factory/mill are a standard product available through distributors or even box stores, whereas no such products are in distribution in the US, and have to be made by the builder, which is why 1x milled lumber furring is more common on custom houses where they care.

          A broadsheet roll product with at least SOME capillary break has a shorter learning curve. It's pretty easy to make the case that 1/4" mesh products or glorified crinkle-wrap are overpriced and under perform compared to battens, but there is effectively zero learning curve, and it's dramatically better than business as usual.

          1. Expert Member
            MALCOLM TAYLOR | | #10


            I'm sure you are right.

            Part of the reason I'm such a vehement proselytizer for rain-screens is that I'm a c0nvert. Before they were mandated here I complained they were only necessary because of shoddy building practices and involved too much work.

            Once I reluctantly had to start using them I saw not only the benefits, but how quickly you could bang them up. The battens take next to no time or special skills. I can see how builders unfamiliar with rain-screens might be more comfortable using mesh, but once they go that route, it's going to be hard to get them to change practices once again. Go battens or go home!

  3. Ben_Bogie | | #11

    Ben is continually frustrated by Michael being stuck in his ways...

    Good follow up Carl!

  4. user-1072251 | | #12

    Aren’t most of the mesh products plastic? I think there is a huge benefit in using a renewable product with a low carbon footprint, (strapping) rather than increasing the amount of plastics in our homes.

  5. user-1072251 | | #13

    Wood plaster lath strips also work great & cheaper than strapping.

    1. brendanalbano | | #14

      I see a fair amount of plaster lath strip rainscreens around town here in Portland, OR, where rainscreens aren't explicitly required by code, but are still fairly common. (The code here requires a rainscreen, but then has an exception allowing for a drainable WRB instead).

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