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Energy Solutions

Cork Insulation on Our Farmhouse

Why we chose cork exterior insulation for our net-zero-energy house

Installing cork insulation on our farmhouse.
Image Credit: Alex Wilson
View Gallery 6 images
Installing cork insulation on our farmhouse.
Image Credit: Alex Wilson
The cork arrived three-to-a-pack, and we've been storing it in our barn all winter.
Image Credit: Alex Wilson
Bundles of cork awaiting installation.
Image Credit: Alex Wilson
Another photo of the bundles of cork insulation.
Image Credit: Alex Wilson
Detail of the cork insulation, showing the shiplap profile.
Image Credit: Alex Wilson
Installation proceeding. Our barn, which will hold PV panels on the south-facing roof, is in the background.
Image Credit: Alex Wilson

Among the innovative — some might say weird — products we’re trying out at our Dummerston, Vermont farmhouse, none is more unusual than the expanded cork insulation we’re currently installing as a layer of exterior rigid insulation. As I mentioned in a blog last summer, cork insulation has a great story behind it.

Cork? You’ve got to be kidding!

I first learned about expanded cork insulation years ago when exploring the attic of a 1920s-era home in Brattleboro. I found a rigid boardstock insulation comprised of cork with plaster on one side. It was made by Armstrong, which was then a company making cork products but is today one of the world’s leading manufacturers of flooring and ceiling products.

It turns out that the product was invented by accident in 1893 in New York City by a boat builder, John T. Smith. The cork granules he used to fill life preservers became clogged in a large tin funnel, and that slipped into the coals of a fire used to steam oak staves. When the owner of the shop discovered the tin funnel the next morning he expected the cork to be burned up, but instead it had expanded to fill the form and solidified into a solid block.

Smith experimented with the process and patented it as Smith’s Consolidated Cork, which he licensed to Armstrong. It was used for several decades for insulating buildings — especially cold-storage buildings. The apple storage building at historic Scott Farm in Dummerston, built in the 1920s or ’30s, is insulated with this product.

Why I like cork

Cork is a remarkable material. It is the outer bark of a species of oak tree (Quercus suber) native to the Western Mediterranean region. This thick, spongy bark protects the trees from fire. It can be peeled off every nine or ten years, and grows back. The bark is still harvested in Portugal, Spain, Algeria, Morocco, Tunisia, France, Italy, and a few other countries, much as it was 2,000 years ago.

The primary use for cork is for wine bottles. The “corks” we all know are punched out of the bark in a really simple process. The residual cork (about 65-70% of the material) is processed into granules that are processed into a wide variety of uses.

To make cork flooring, floor underlayment, and gaskets, the granules are glued together and sliced into thin layers. Cork makes a great flooring material, because it is soft underfoot (resilient) and it absorbs sound. You will often find it in libraries, for example, due to those acoustic properties. My aunt and uncle installed cork floors in their Connecticut house in 1951, and that flooring is holding up very well more than 60 years later.

Cork is produced from ecologically rich forests that support significant biodiversity, including the endangered European lynx.

Avoiding foam insulation

The primary reason I’m excited about using cork insulation on our house is that I don’t like some of the chemicals used in conventional foam insulation. Extruded polystyrene is made with a blowing agent, HFC-134a, which is a very potent greenhouse gas that is contributing to climate change, and nearly all foam insulation materials contain hazardous brominated or chlorinated flame retardants. I’ve most recently written about these concerns here.

Cork, by contrast, contains nothing but cork — nothing! As it is produced today by Amorim Isolamentos, S.A., the granules are poured into large vats and heated with steam in an autoclave at about 650°F for 20 minutes. The heat expands the granules by about 30% and releases a natural binder, suberin, that exists in the cork. There are no added ingredients.

Isn’t cork a limited resource, or isn’t there a cork blight?

I get these questions whenever I mention cork. As far as I can tell, these were rumors that were started by companies making synthetic bottle stoppers for the wine industry that were trying to take away market share from natural cork. No, to the best of my knowledge there isn’t a blight.

Cork is a somewhat limited resource, so cork insulation will never come to dominate the rigid insulation market. But the resource is not disappearing and clearly it is a renewable resource.

The sad part of the story is that as synthetic corks and screw-lid wine bottles have replaced traditional natural-cork bottle-stoppers, the demand for cork has dropped. I’m told that in some parts of the western Mediterranean region, cork oak forests are being cut down and the land converted to other uses.

Shipping cork to Vermont from Portugal

I’ll admit that shipping cork across the ocean is a significant downside. While ocean shipping is very energy-efficient (far more efficient than shipping over land), the fuel used — a low grade of diesel — is very dirty. I struggled with that as I thought about the use of this material for our house. I’ve reviewed an analysis Amorim Isolamentos has done on the carbon footprint of their material, and it’s not too bad.

Ultimately, I decided that by publicizing our use of this material I would help generate demand that might help preserve the cork forests. I don’t expect that the U.S. will ever become a huge market, but for people wanting natural and rapidly renewable building materials or who have chemical sensitivities, cork is an option that can be considered. (Relative to chemical sensitivities, care should be taken to make sure that there isn’t sensitivity to the odor of expanded cork, which has a somewhat smoky smell — no doubt due to the heating.)

Our use of cork insulation

We are installing cork as a layer exterior insulation on our farmhouse. The air barrier for the significantly rebuilt early-1800s house is a fully taped and airtight Zip sheathing layer. On the interior of that will be 7 1/2 inches of cavity-fill insulation. On the outside of the sheathing is the 6-inch layer of cork.

The building enclosure is designed so that the cavity-fill insulation layer can dry to the interior (if it ever gets wet), while the cork can dry to the exterior. On the outside of the cork will be a layer of housewrap (a high-performance German product, Pro Clima Solitex, distributed by 475 High Performance Building Supply), vertical strapping to create a rainscreen, and wood clapboard siding.

We ordered the cork with shiplap edges so that joints would not extend all the way through the material. We had debated ordering 3-inch thick cork and overlapping the joints — and that strategy would have worked fine — but we decided that we could save on labor with the thicker panels.

Next week I’ll provide some specifics on how the cork insulation is being installed. Eli Gould and his crew have done a wonderful job at figuring out how to work with the stuff; some of the details are quite tricky.

Alex is founder of BuildingGreen, Inc. and executive editor of Environmental Building News. In 2012 he founded the Resilient Design Institute. To keep up with Alex’s latest articles and musings, you can sign up for his Twitter feed.


  1. davidmeiland | | #1

    Did you consider
    mineral wool panels?

    I'm trying to determine what to use for an upcoming project... cork vs MW, with foam in distant third place.

  2. Alex Wilson | | #2

    Cork vs. mineral wool
    Mineral wool is a lot less expensive, but with an exterior insulation system, as we used, there is the issue of the compressibility of the mineral wool. Cork is quite solid. With mineral wool you'd need to figure out a way to properly support strapping for a rainscreen on the outside of it. I'm sure that's doable and would love to see some details for such a system.

    Someone just told me that there's a mineral wool product coming out that higher density than even the Roxul TopRock product (which has a density of up to 8 pcf); I think I heard the density of this new product would be as high as 12 pcf. At that density, the mineral wool may work nearly as well as cork, relative to compressibility and support for strapping.

  3. Mike Eliason | | #3

    we'll be installing


    we'll be installing some of albert's cork for an uber small Passivhaus in seattle in a few months (4"). what is the thinking on the solitex - belt and suspenders? worried about windwashing?

    i spoke w/ graham finch of RDH in Vancouver at the PHnw conference last week, he mentioned roxul's 12pcf density toprock, and that they're liking application for exterior insulated walls because it doesn't budge under compression.

  4. jameshowison | | #4

    Why wrap on outside?
    Cool stuff, thanks for sharing this. I wondered if you could talk about why you need a layer of housewrap outside the cork? Seems like your WRB is the taped Zip sheathing, and the cork is not air-permeable, so no wind-washing, so what's the housewrap doing for you?

    I wonder if you could also address the question of relative cost vs MW or foam? Not that I think that one ought always go with the least currently expensive option, but I'd like to have some idea.

    Appreciate your posts.


  5. Alex Wilson | | #5

    Housewrap over cork
    I don't really know if the Solitex weather-resistant barrier (WRB) is truly needed. Several building science experts suggested it as an extra precaution, and it seemed prudent. But I could probably have been convinced to skip the WRB. In Portugal this insulation material is sometimes being installed as the weather-exposed cladding--which seems risky to me--but it points to its durability. Our air barrier, as you noted, is provided by the Zip sheathing. The Solitex has such high permeability that I'm not worried about it trapping moisture.

    It remains to be seen just how easily the WRB can be secured to the cork and held in place until the strapping is applied. The strapping will be screwed to the frame through the cork--and those 8" Simpson Strong Tie screws will provide the primary structural adherence for the cork.

  6. heinblod | | #6

    carcinogenic and fire risk materials
    Isn't that bitumen holding the granules together to form a sheet?

  7. RobFisher | | #7

    WRB helps with flashing?
    Will the additional WRB help with the integration of flashing? I am of the belt and suspenders inclination when it is affordable. Makes sense to me as a primary water shedding plane.

  8. Alex Wilson | | #8

    Cork insulation binder
    There is no bitumen in the cork insulation. As explained in the article, to produce the rigid boardstock material, cork granules are heated in a high-temperature autoclave, a process that releases a natural binder in the cork: suberin. That suberin holds with granules together forming the panel. The cork will burn, but not easily. When a 40 mm piece of the cork insulation is held over a torch (see photo), it will take over an hour to burn through--compared with about six seconds for polystyrene.

  9. user_8675309 | | #9

    screw length?
    I'm just checking the math on this. 6 inches of cork + 1/2 inch zip sheathing + (I assume) 3/4 strapping = 7 1/4 inches of material. An 8 inch screw seems a little on the short side of things.

  10. Alex Wilson | | #10

    Screw length
    9" screws might have been better (if they exist), but by countersinking into the strapping a bit, I think the 8" will be all right. Eli thought that 10" screws (the next increment in the Simpson Strong Tie line) would have been a lot of work to screw in--they are pretty thick screws. The cork is non-structural and it is bearing on a shelf of coated Foamglas at the bottom of the wall (the same thickness), so I think we'll be all right.

    These sorts of questions point out the challenges in working with new materials and new systems. There isn't a lot of modern experience working with cork insulative sheathing, so Eli's crew is learning as they go. Next week's blog will address a lot more installation details with the cork.

  11. esp71 | | #11

    Are there any known issues with cork and the various little critters that like to eat wood? Is the cork treated with anything to resisst them? Could you treat it with a borate product if you lived in a high risk area?

  12. Gregory La Vardera | | #12

    cork is an old time insulation
    I've a client with an old masonry dairy building in our neighborhood. The milk storage room was lined with cork to insulate it. Walls, ceiling, and under the slab.

    I think you are doing the right thing with the additional air barrier layer. Unless you are using something like mineral wool that will shed water I think the layer you are putting over the cork will keep the cork dry, and allow you to properly layer and flash your openings. The Solitex is great, but given you are working over Zip you could have probably use dumb ole' building paper.

  13. albertrooks | | #13

    The farm house is looking great and I like the choices that you and your team are making. I think the choice of standard grade cork (7lb/ft3) with overlap joinery was a good one.

    On the subject of using cork as exterior siding, I've got faith that it will last. I've walked a few large buildings in Portugal and they look healthy at 6-10 years old. The projects that I've inspected are wearing as well as any wood siding product, and are loaded with character. The medium density cork (9lb/ft3) is left completely untreated.

    I've begun an effort with Amorim on creating a US friendly "brand" for Amorim expanded cork insulation. Weve created new literature, sample pieces and an informational website. the idea is that since distributing cork is best done regionally, US distributors can idealy share the same marketing resources. We plan on sharing resources with other innovative distributors in the US and have made some initial talks with a few folks on your side of the country.

    It's a stab at creating an informal "Cork Co-Op" of US distributors. One of the most interesting features of will be it's "Corkitecture Bolg". It's a shared project blog intended to cover the successes and failures of cork project across the US. It will be interesting to see the wide aray of project designs and layering that come from all climate zones. (I have to admit here that I stole the name "corkitecture" right out from under Brute Force Collaborative). also shows some good pics of cork facade "in action".

    Hopefully the Corkitecture blog grows with time. We will have a good start with projects such as yours, BFC's Shiga Shack, Chad Ludermans "Philly Facade" (named by me, not Chad) and who knows who else as submissions come in and/or reuse permissions are granted.

    Also, I'm sure your team can find some good SIP screws, but if not, I've been down that road already and have some double thread, countersunk head exterior insulation screws from 8" to 18" long. They are what is typically used to apply low density insulation like mineral wool in the thickness range of 4" to 12" thick without compressing. Give a shout if needed.

    It's these interesting application challenges that make it fun for me to go to work everyday.

    Keep up the good work!

  14. dankolbert | | #14

    SIPS Screws?
    Alex - have you already bought the Simpsons? If not, look into SIPS screws - various manufacturers, somewhat cheaper, wider variety of sizes, and the flat-ish heads work better for this type of application. Any commercial roofer should know where to get them, or there are plenty of on-line sources. We get ours from Beacon Sales - they have a branch in Shelburne.

  15. heinblod | | #15

    carcinogenic material?
    Thanks, Alex Wilson.

    Looking through google I came along a warning concerning the expanded cork, it releases benzpyrene and PACs, carcinogenic materials.
    This would explain the smell from the boards.


    " Risiken nur für expandierten Korkschrot bekannt, da durch das Erhitzen polyzyklische aromatische Kohlenwasserstoffe≡ (PAK≡, Benzpyren≡) entstehen "

    I translate:

    " Risks only from expanded cork granules because the heating creates PAC (polyaromatic carbo hydrates) and benzopyrene "

    These are carcinogenic substances, their presence would explain the smell reported.
    Natural cork doesn't smell. Maybe a bit of cut timber.

    Portugese cork plantations are monocultures where heavy usage of weedkillers is normal, wild
    fires which are normal in cork plantations but ruin the product (the bark) are controlled by killing the undergrowth in these plantations.

    These sprays love to stick on rough surfaces, on tree bark for example.

    Whilest wine corks are made from the younger,lower part of the harvested bark the cheaper waste (the upper/outer layer) is turned into shoe soles and insulants.

    Was an analysis done on the off-gasing of these boards?

  16. MarkWD | | #16

    top of wall
    Alex, I am curious how you addressed the air sealing for the air barrier at the wall and roof--is it a chainsaw retrofit?

  17. Alex Wilson | | #17

    Air barrier in our retrofit
    The house is entirely sheathed with Huber's Zip sheathing with joints taped, and the roof is entirely new, using 16" scissor trusses as rafters. There were some challenges we faced, including the beams running the length of the house at the top of the eave walls that extend several inches out past the wall plane; this made for some complex boxing in to achieve the air barrier we desired. Just today we were doing some additional air-sealing prior to insulating the roof and cavity walls. I'll write about this later, but we used Knauf's EcoSeal system (like Owens Corning's EnergyComplete); we did that with a blower door operating to exaggerate leakage sites to aid in air sealing.

    The sheathing layer provides the continuous air barrier, and the cavity-fill insulation will be able to dry to the interior and the cork insulation to the exterior.

    I'll report on air sealing strategies in a future blog, including measured performance.

  18. Alex Wilson | | #18

    Cork and health
    You raise a valid concern about cork in terms of polycyclic aromatic hydrocarbons (U.S. terminology). These are the compounds that are implicated in barbequed or otherwise charred food. When I pondered this question after getting my first samples of the insulation and noticing the modest smell, I decided that if I put the cork on the outside of the air barrier, risks would be minimal--probably at least an order of magnitude less than the risk we choose to live with in heating with wood (and almost certainly less than the risk of driving to work). We all live with risks, and I've made a judgement that the risks of PAH offgassing from cork insulation on the outside of my house is less than the risk of flame retardants in foam-plastic insulation. But I would be interested in digging into this issue in more depth. I have raised similar concerns about pyrolyzed wood (which has a much stronger charred-wood smell).

    As for your comments about cork forests and what portion of the bark is used for what purposes, I have my doubts. Most of Amorim's forest operations are certified according the principles of the Forest Stewardship Council (FSC), which as far as I know, prohibit herbicides. And I am led to believe that the forests support rich biodiversity. Your claim about bottle corks being from the "younger, lower" bark while insulation is made from the "upper, outer" bark doesn't match my understanding of plant morphology; I think of cork growing out not up.

    I should add that I've spent many years reading claims about building products, and the first thing I do when I come across information that disparages one material or another is look at the source of that information. Not uncommonly, that information comes from a competing industry and needs to be taken with a grain of salt. I wonder how much of your information on cork falls into that category?

  19. heinblod | | #19

    cork insulation - a tested and certified material ?
    I wonder if the cork boards are actually a certified material?

    Tested according to international test methods and certified for the purpose?

    The DIY fire test with a blow torch would not even stand up to the lax US demands on a fire safety test.
    Fire safety tests (as well as emission test) have to be done according to ISO , for example
    ISO 13785-2:2002.



    The newer version (2012?) demands not only a corner but a shaft test.

    Are there any test results from independant ISO-certified labs available?

    Or is it just " I guess " knowledge which is available on the product and its aplication?

    Note that not only the material itself should be tested but its aplication in a fascade system.
    Emitted volatile components could not only cause health problems in the long term but also destroy load bearing elements, interacting with other substances. For example the plastics of pipes and cable insulants, wind breaks and so on.

    So my question for independant test results according to international standards.


  20. heinblod | | #20

    searching for data - Amorim cork insulation
    Whilest searching the web I checked the home page of Amorim, looking for any data on certification processes. No sucess.

    Amorim pt. provides this page about its USA enterprise:

    where it states that the material is 100% natural. Digging further and checking the refered instititution's page ( greenspec) I come across a statement where it says that the cork boards are an accustical insulant made with PU binder:

    Digging in German web material I came across a data sheet where the aplication method for cork boards (as a thermal insulant for fascades) is a glue-and-plug method. The cork boards must be glued with mineralic based glue and - after drying - be plugged:

    See for " Verarbeitung " (working method) on page 1

    The fire resistance class is stated with " B2 " in both data sheets.

    Amorim Germany has only bottle stops for sale on their home page, no building material and hence no information about any certification process:

    This web page is new, updated 12/2012, so I guess some info on building products - if available- would be there.

    So there is no data on their Portugese home page about certified building products and nothing on their German page.
    The USA page of an independant source they mention (greenspec) speaks about an acoustical insulant made with PU-binder ....

    The Amorim pt. homepage mentions in their english web page a " seal of sustainability ", nothing else:


    "Corticeira Amorim acknowledged by the Portuguese Platform for Sustainable Construction as the only gold level company "

    Amorim does not specify what product was 'sealed' nor does it link to the 'sealer'.

    So any solid data about the product would be more than welcome.


  21. heinblod | | #21

    standards and certifications - Amorim cork boards
    Checking further the web I found the EN certification for cork boards made from expanded cork:

    EN 13170:2012

    See for example

    Using google searching for the term

    " EN 13170:2012 + Amorim "

    resulted in no result .....

    Is this board as featured in the article by Alex Wilson (s.a.) an uncertified material ?

  22. Alex Wilson | | #22

    Cork insulation performance
    The acoustic product you included a link to from our GreenSpec Directory is a very different product than expanded cork insulation. Indeed, both cork flooring and acoustic underlayments are made using binders. While those are not all-natural products, I like them also.

    Digging back into the research I did a year or two ago on cork insulation, attached is a report on indoor air quality testing from France. As for fire testing, my understanding is that cork satisfied the European equivalent of the ASTM E84 Steiner Tunnel Test, but I could not put my hands on that test report. The material has not yet gone through the American ASTM-E84 fire testing--flawed though that testing is.

    Also attached is a general 66-page document on cork that addresses many of the questions you raise.

    Listings of some environmental certifications carried by Amorim Isolamentos's product can be found here:

  23. Francisco Simoes | | #23

    Standards, certification, doubts
    First of all, thanks Alex for the blog and for the great work that is being done at your farm.
    Hein, thank you for adding new data to the discussion but I believe you are searching for cork and mixing a lot of ideas from different cork products. Alex thank you for your replies.

    To make it clear and simple regarding Expanded Insulation Cork:
    Since expanded insulation cork was discovered by accident in NY back in 1890s some applications appeared but note that Expanded Insulation Cork can and is produced in different grades and densities, depending on its final application.
    Amorim Isolamentos is nowadays manufacturing leader and produces under different brands depending on the market. Thermacork as Albert mentioned in a previous comment is the US brand while Corktherm is the German brand.

    Regarding standards and certificates:
    You were only looking into the non-standard fire test but Expanded Insulation Corkboard manufactured by Amorim Isolamentos conforms to EN 13170 + EN 13172.
    > Thermal conductivity tested by the independent laboratories: CSTB (France) and LNEC (Portugal).
    > Industrial quality /Quality control by CSTB (twice annually).
    Other certifications (in addition to EN 13170):
    > MPA Stuggart – Ogo-Graf-Institut (quality verification).
    > ARGE KDR – Zertifikat no. - R0700144 “R” green 100% vegetal.
    > ACERMI by CSTB, France (Industrial and quality control).

    Regarding the VOCs it was already discussed before… The most demanding country in Europe for the VOC testing is France and we got an A+ evaluation, we attach a short PDF with the resume (you already have the full data in previous reply by Alex).

    You can find some other data for the US market under
    One historical curiosity not yet mentioned in any website: Workmen installing cork insulation on ceiling during White House renovation:

    That German information regarding benzopyrene appeared maybe about twenty years ago and is completely out of dated. We guarantee that the material contains less benzopyrene levels than the ones that must comply with roasted chicken legislation!

    Since you are German and did some digging in German we should add the following information regarding Germany:
    Amorim Information (Amorim has different companies in Germany, for stoppers, for flooring and for other applications). That might explain why you ended up in another website.
    Correct link:
    Other information in German mentioning the "raumluftanalyse":

    Hope all your doubts are clear.

    Thank you.
    Francisco Simões
    Amorim Isolamentos

  24. heinblod | | #24

    Approval expired
    I try to get some official statement on the legality/certification of these cork boards.

    And ask.

    The manufacturer (?) is now involved, linking to this document from 2004:

    which is also mentioned here:

    ( " MPA – Institute for Materials Testing of the University of Stuttgart (Germany) – certification of construction materials in terms of their suitability and production process according to existing standards; ")

    When I check the validity of this document (the official German approval for a building material) I use the official data bank of Germany.
    Fraunhofer IRB, the data manager for Germany's building material approvals tells me that this "certificate of approval Z-23.11-1344 " is "abgelaufen ", that this product has no German approval anymore.
    I know that approvals have to be extended every 5 years.
    This linked document from 2004 shows an approval from 2001.

    " Zulassung Z-23.11-1344
    Gegenstand: Wärmedämmplatten aus Kork 'Corkherm 040'
    Prüfstelle: DIBt
    Antragsteller: Amorim Isolamentos, S.A:
    Seiten: 5

    Ausstellungsdatum: 22.05.2001 – abgelaufen "



    Since 7 years.


    So I wonder what is going on here with this advertising.

    I'm not looking for advertising brochures nor for outdated documentation.

    I'm looking for the official and valid approval of this building material .
    Not more.

    A direct link to the official documentation, please ! Like http ........ or www. ........

    Showing official test results, showing the official valid approval as a building material.

    The official fire testing results, the official working methods (fixing!) are part of the approval as a fascade material. For these I'm looking.

    The work methods/ aplication methods are part of the official building material approval in Europe.

    Is there a misunderstanding ? Or is there a smoke granade being fired on purpose ?

    Please give the link to the official documention showing valid test results done under ISO standards.


  25. Francisco Simoes | | #25

    Official documents + other information
    Dear Hein,

    Once again thank you for allowing our reply. I only intervened before and now in order to clear the subjects but note I have no intentions in making this forum into a 1:1 Q&A.
    I personally do not understand your bellic terms like granades but I am really happy to be able to help you because at the end we will both be helping everybody and Cork in general.

    I suggest you to visit these websites and watch the video:

    We will inform our German partner to update his website and references, thank you for bringing it to our attention. We attach the official documents you are looking for, all 100% valid, dated and with all technical information you cannot google - I explained before we have brand thermacork for US and corktherm for Germany. In Italy it is Corkpan and France is Corkisol, this will help you understand some documents.

    We have other certificates mainly regarding the ETICS (or EIFS) application but those are specific from other partners.

    Last but not the least, you (and everybody who contacts us) are mostly welcome in Portugal for a forest and factory tour to check in situ everything with much higher detail.

    Hope all your doubts are now clear. Thanks once again.

    Kind regards,
    Francisco Simões

  26. GBA Editor
    Martin Holladay | | #26

    Response to Hein Bloed
    It is fascinating to observe differences in attitude between U.S. building professionals and German building professionals.

    Alex Wilson shows an interest in the safety, performance, and environmental appropriateness of cork insulation.

    You seem very fixated on whether an official document filed with the German government is up-to-date or may have lapsed. This focus on paperwork over substance was the subject of novels by Franz Kafka. Taken to extremes, this focus can lead to categorical errors.

  27. albertrooks | | #27

    No smoke here...
    I've made two trips to Portugal and have walked cork forrest on both occasions. They are exceptionally beautiful and appear diverse (to me) though I have no documentation to offer as proof of their diversity.

    Attached is a picture of a friend and I in the cork forest outside of Evora Portugal. This can help one can get a sense of what a cork forest looks like. We are standing in front of a typical Cork Oak.

    Hopefully my "bias" is quite clear. I'm all for cork both "idealistically" and "commercially". I don't feel that the two positions are mutually exclusive.

    Commercially, I've invested in expanded cork insulation as a building insulation by ordering a very large inventory. My clear hope is that that investment pays off and that people use cork as insulation.

    idealistically Im for the use of cork as insulation and a building facade because it simply makes me "feel better" being around it. I live in the Pacific Northwest and grew up at a time that most building materials were some form of wood. I have to say that I'm a little saddened that most of the materials that are used on projects are now vinyl, plastic or cementious. There are really no more naturally weathered wood facades. They all now get a coat of paint to conceal their origins. Designers are forced to vary the siding products and paint colors in order to break the uniformity.

    The issue is a very simple one to me: Harvesting cork bark (to me) looks substantially better for the birds, plants, trees pigs, cattle, and (lest we forget) people, than sites where we extract the materials that create plastic foams, vinyl window frame, cementious sidings and the host of other heavily manipulated products.

    The cork facades that I've touched with my own hands have the look and feel of a naturally weathered product. Being of flesh and blood, and from the Pacific Northwest, I respond better to that on many levels. It makes me think of the work of Christopher Alexander and his life long quest to understand why certain patterns and buildings create different responses in human beings. Why some things are "beautiful" and others are not.

    Perhaps my viewpoint is overly simplistic and lacking in documentation. Yet... I still prefer it.


    Albert Rooks
    The Small Planet Workshop
    WestCoast Associates Inc.

  28. heinblod | | #28

    Thanks, Francisco Simoes, now I see the correct documentation:

    Still missing is the manual on how to use the boards, esp. the fixing methods.

    When publishing documentation make sure the documents are valid, not outdated.

    And when looking at a certificate issued in Italy on the first of January

    then we are aware that the 1st of January is a public holiday in Italy.

  29. GBA Editor
    Martin Holladay | | #29

    Response to Hein Bloed
    Thanks for letting us know that "the 1st of January is a public holiday in Italy."

    Clearly, if any Italian bureaucrats were working on January 1st, that must be evidence of a conspiracy or fraud. I'm glad you caught that, and brought it to our attention.

  30. heinblod | | #30

    Thermal insulation
    Martin Hllladay wrote:

    " Hein,
    It is fascinating to observe differences in attitude between U.S. building professionals and German building professionals.

    Alex Wilson shows an interest in the safety, performance, and environmental appropriateness of cork insulation.

    You seem very fixated on whether an official document filed with the German government is up-to-date or may have lapsed. "

    You're lacking the potential to interpretate the questions I have asked, maybe because you are fixed to the insulant. And not to the building of a sustainable structure.


    The thermally insulating quality of a wall is important when designing low energy consuming buildings.
    It is of absolute no importance what performance the individual materials used are showing on their own.


    An EPS board is a certified material
    A PVC insulated copper cable is a certified material.
    Both are are not allowed to come in contact with each other, despite being both wall elements.

    So a cork board (as spoke about) must show a manual on usage and behaviour to be used in a building.
    This work manual is still not published here, neither by the manufacturer nor by the featured user.

    A DIYer would ask for better documentation on a can of wall paint, seriously.

    ALL fascade elements should show a manual on how to use them and on how not to use them.

    Since the entire assembly must perform. Not only individual parts of it on their own.

    I can't believe that a professional builder would use a material which is non-documented or guaranteed in its workmanship. Not even in the USA.

  31. heinblod | | #31

    about Italien "documents"

    Sometimes irregularities on documentation (outdated ones or dubiously dated as presented above by Francisco Simoes) can be seen by an amateur. If literate and used to cross check information.

  32. GBA Editor
    Martin Holladay | | #32

    Response to Hein Bloed
    You wrote, "I can't believe that a professional builder would use a material which is non-documented or guaranteed in its workmanship. Not even in the USA."

    Well, documents only get you so far. There are lots of approved, well-documented building materials that perform poorly; fiberglass batts come to mind, but there are many others. On the other hand, many green builders choose to build with framing lumber that comes from a local sawmill -- even if the lumber has no grade stamp on it. Other builders choose to build with straw bales or mud -- and clearly, the mud manufacturer is remaining silent when it comes to installation instructions.

    In short, builders need common sense. A building materials manufacturer with lots of money can easily get materials approved, even when the long-term performance of the material is far from proven. On the other hand, local materials gathered in the woods, without any documentation at all, can perform very well indeed.

    I love documents, and spend most of my working day reading them. But let's not confuse the map with the territory.

  33. Francisco Simoes | | #33

    Reply to Hein
    Dear Hein (again),

    Expanded Insulation Cork Board manufactured by Amorim Isolamentos is a certified material.

    Regarding Italian ICEA certificate I attach the outdated one just for your records as it seems you like the paperwork - its older validity was 31 December.
    Personally I am happy you did not mention any of the German certificates - you must have already crosschecked in all possible sites.

    Every building system is different and we have a lot of other documents for different applications and I do not understand what is missing for you. Again in German please check one example:

    The big picture about cork in general for you:
    The world is a better place with cork and its applications.

    Again, feel free for forest and factory tour (we had alternative insulation manufacturers who made visits in the past so it would not be a first time for us).

    Kind regards,
    Francisco Simoes

  34. mikeolder | | #34

    I found a home that used cork as structural blocks.

    What I'm more interested in is the cost, as usual.. I like the warm look but to bad they didn't make rolls to minimize seams.

    I guess it's not a fair comparison because cork adds R-value, but what would be more expensive? A cork or vinyl facade?

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