Cork insulation

[whatismisophonia]

Is it just me, or does it seem like the U.S. is always behind Europe?  First, it was rock-wool insulation over fiberglass, and now expanded cork over poly.  The following is taken from an article at http://www.greenbuildingadvisor.com/blogs/dept/energy-solutions/expanded-cork-greenest-insulation-material :


"Cork as a building material
I have long been a fan of cork flooring, floor underlayment, and acoustical wall coverings. These materials are made from residual cork that remains after punching cork bottle stoppers from the bark — which consumes only 25% to 30% of the bark."

"For cork flooring and these other products, the cork granules are glued together with a binderand then sliced into the finished products."

"Expanded cork insulation is quite different. The same cork granules are used, but they are exposed to superheated steam in large metal forms. This heating expands the cork granules and activates a natural binder in the cork — suberin — that binds the particles together. In an in-depth product review about expanded cork insulation in the August issue of Environmental Building News I describe the fascinating history of this process. (It was invented by accident in New York City in the late 1800s)."

"After producing these large billets of expanded cork, they are sliced into insulation boards in a wide range of thicknesses — in both metric and inch-pound (I-P) sizes. In I-P units, thicknesses from a half-inch to 12 inches are available — with dimensions of 1' x 3' or 2' x 3'."

"The material is 100% natural and rapidly renewable as defined by the LEEDRating System. It is durable yet ultimately biodegradable, produced from sustainable forestry operations, and a byproduct from the cork bottle-stopper industry. Though there is significant shipping energy required to bring it here, shipping by ocean-going vessel is relatively energy-efficient. It’s hard to imagine a greener building material."

"Cork insulation performance
Expanded cork insulates to R-3.6 per inch. It has a density of 7.0–7.5 pounds per cubic foot and compressive strength of 15 psi (with 10% compression). It is intermediate in its permeability to moisture — with a 40 mm layer having a permeance of 2.2 perms. Although the expanded cork insulation gives off a smoky smell, a test report I examined showed the material to pass France’s stringent requirements for a dozen volatile organic compounds (VOCs) with flying colors. Cork also has superb sound-control properties."

"From a fire-resistance standpoint, it meets the European Class E designation (the standard met by other rigid insulation materials) without the need for flame retardants that are used in the most common boardstock insulation products. A 40 mm-thick piece of the boardstock insulation held over a torch will resist burn-through for an 60-90 minutes, compared to less than 10 seconds for expanded or extruded polystyrene, which meets the same Class E designation. (The flawed manner in which we determine fire-resistance properties of materials is the topic for another article.)"

"Cork insulation has been used as a rigid insulation material for decades in Europe. It is not uncommon to install an 8- to 10-inch layer on exterior walls and a 10- to 12-inch layer on roofs. The first Passive House built in Austria (in 1995) used a 350-mm layer (nearly 14 inches) of the material. It is typically used as an exterior insulation layer, much like polyisocyanurate."


One-up over cotton you think (concidering the price goes down if the harvesting becomes a bit more industrialized)?

[Randy S]

Seems like you believe everything you read without having any field experience to back it up...


North American distribution channels are just being set up, so pricing is far from certain. But Simoes told me the price to a distributor will be about $0.70 per board-foot, not including shipping, markups, or the exchange rate. If those mark-ups come to 50%, the cost per board foot would be $1.05 and the cost to achieve R-19 would come to about $5.50 per square foot for cork, vs. $1.10 – $1.60 for polyisocyanurate insulation and $2.00 – $2.25 for extruded polystyrene.

we sell cotton fiber R-19 @ $0.93 sqft.

[Randy S]

I also reviewed the manufacturer's website and couldn't find any STC,NRC,or IIC ratings any where to back up the claims...maybe you can show me if I missed it.

 

[whatismisophonia]

  ...slander much?

I dont ****ing believe everything i read, and I happen to be a sceptical person about most things in general, relying heavily on evidence, unlike most people i know.  I was just wandering if anybody had heard of the stuff and had anything to say about it.  Also, I'm aware that the price is high, but that's mostly because the marketing isn't behind it in the U.S.; who knows what will happen in the future.  If people over there use it a lot, it must be worth something...  Regardless of any lack of data on its sound deadening capabilities, we know that cork has been used a lot for noise control in general.  If anything, I'm simply looking for info on it myself because it's interesting, so back off.

[Randy S]

well, I will apologize if you feel I have slandered you.
Cork is really an outdated product....seldom used in high performance impact systems and really only use cork for industrial style vibration pads....which are 50% or greater decouplers.
There are other products all the way down the line for impact problems, airborne problems and hands down absorption coefficients that out performs at a lessor cost.

[whatismisophonia]

I don't mean to be hyper-defensive or anything, it's just that it was kind of an insult to me personally.  In my studying of noise abatement, I've checked several references and read posts from several different people who study acoustics and have in field experience no less credible than yourself; and I am pretty good at inferring from data, as I was a college student for a few years, studying a variety of topics.  Ultimately the conclusions I've drawn from all the info, posts, and acoustical data are concurrent with what real live experience I have gained in soundproofing my bedroom.  Honestly, I don't want to come off like a know-it-all, I was just freaking curious; I just figured it would be convenient to show the info that I had recently read about it.

That being said, one style of insulating that has gathered more attention in recent years is the idea of insulating with only rigid insulation, with the stud bays and rafters being open (no cotton, rockwool, or cellulose here) and only used for support; the fact that all the insulation is clad over the framework nullifies any heat coupling effect of the framework.

As the several inches of insulation would have siding or plaster covering it, one can't help but wonder how well such a structure would compare to a double wall in sound deadening, especially if expanded cork is used (it would have to be better than the poly right?).
 
The article mentions that gathering the cork is somewhat labor intensive; just the same though, there is potential for industrialization, not to mention breeding varieties of this tree that can be grown in different climates.  I just figure it's worth a look into.

[Randy S]

I hear what your saying....
If you really want to see cutting edge thermo insulation properties that can be applied in sound control take a look here...this blew my mind and is the direction I would like to see us go in the future once stable.
http://www.aerogel.com/

[Randy S]

mind you I cant see it applied in impact applications.... but airborne sound and thermo control most definitely.

[Randy S]

take a brief look. http://www.youtube.com/watch?v=G2TbHTU-QNs

[whatismisophonia]

I had learned about aerogels last year while researching ways to improve heating efficiency for greenhouses; the problem being that in the Midwest and further north it is extremely costly to heat a greenhouse due to the complete lack of insulating properties of a typical polyethylene greenhouse covering.  Aerogels work good for slowing heat transfer due to the sheer amount of microscopic air pockets, and the materials themselves are usually very much see though, especially in thin sheets; and, as your info shows, there is possibility for even greater transparency to be developed in the future.

This is all strictly for reducing heat coupling and transfer; however, it’s thin "lighter-than-any-other-known-solid" nature with extremely small airgaps and inability to be used in a CLD system stumps me on how it could be useful for noise abatement.  And this didn’t help either: http://www.hypedupacoustics.co.uk/data-a-advice/help-a-advice/130-aerogels-slim-line-acoustic-treatment-for-studios ; not that I believing everything I read, but the info does jive with what I would suspect, and if it's true, the soft stuff would be more useful for impact vibrations than air-born noise.  That would be reversed in a solid board, though even if the stuff were more tightly packed, it seems like it would have the same problem as rigid foam insulation.  Now, if this stuff were laminated to a MLV layer and attached to the exterior or interior of a framework before sheathing or drywall, I’m sure it would be pretty useful.  The problem is the amount of cocaine you'd have to sell to pay for the whole thing. 

My thinking is that the problems of heating and cooling can already be mostly solved with proper passive design, though soundproofing concerns are a different story of course. 

[Randy S]

to quote you " Now, if this stuff were laminated to a MLV layer and attached to the exterior or interior of a framework before sheathing or drywall, I’m sure it would be pretty useful.""

Bingo... my thoughts exactly...full thermal value in combination with mass and an airtight seal...


They already are making a framing tape out of it that has shown to yield ok results, but there are some inaccuracies with the testing data.