Cork insulation
So I’ve stumbled across this seemingly miraculous cork spray product touted by Mike Holmes. The thing is, they only spray about 1/8 of an inch layer, and commonly on the exterior yet cite energy savings that don’t seem to add up in my mind.
The only thing that I can see such a thin layer doing is acting as an air barrier rather than insulation. In that respect, I was curious what anyone’s thoughts would be on using cork spray in stud bays on the interior side of the sheathing before installing insulation.
I’d also be curious why they can’t do thicker layers. Seems like a real missed albeit expensive opportunity. Does anyone know much about these companies? Are they and any way legitimate or just another gimmick? Thanks!
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Replies
billstyles,
This is how Mike Holmes describes its benefits:
"The performance of cork is not based on an R-Value but rather a U-Value and a K-value.
Vipeq’s Thermal CorkShield is rated with a K value of 0.058 which is quite extensive for a coating that is only 1/8 of an inch thick. This K value, or thermal conductivity rating, stops hot and cold energy at the source and greatly improves the R value that is already inside your walls."
That paragraph makes no sense.
That's pseudoscience. I'm leery of any product that uses pseudoscience in its marketing.
I suspect this is more of an air-sealer than a thermal insulation layer. Might be best used in a retrofit situation where you can't tape the seams of sheet goods, or where the external wrap layer is degrading and punctured. It could also be the sort of thing that works in a flash-and-bat system. Cork spray to close the gaps, some other form of insulation to keep the heat in (or out).
I've also seen it as a flooring, which makes more sense. With a little give underfoot, it could be a useful layer before putting down some other flooring, or in a garage/basement just by itself.
Thanks for your replies, you've basically confirmed my thoughts on the matter. It seems like it has some promise as an air sealer. I wonder if it can be done in thicker layers, because then it sure would be handy.
Anyone actually use this product? Seems to be very limited information on it.
I need to cover up some older brick so they don't get exposed to water. Considering siding, mineral paint, stucco. This cork paint sounds like the least complicated and most effective of the bunch.
I doubt the effectiveness of the material. They're making up units to measure their thermal performance, so I wouldn't trust them at all on that. I'd assume they are somewhere between fiberglass and EPS at best, whic is in the R3-R4 per inch range, so about R 0.4 for a 1/8" thick layer. Even Reflectix can do better than that... All R value is is a measurement of the resistance of heat transfer through the material, so their material can be tested for R value just like any other, and the results ARE comparable as long as the test methodology used is the same for all materials being compared.
Cork may be moisture tolerant, but it's not a moisture barrier, so it's not going to help you with waterproofing.
I would probably only consider this material if it has a price that makes it competitive with other options, but my guess is that it's probably expensive for what it is. It may also be difficult to actually get if there is limited info about it. I've never seen it, and I don't know of anyone who has, either. That doesn't mean it isn't useful in some situations, but it may complicate your project if you want to use it and find out it's difficult to order in.
Bill
I know cork was an historic insulating material in the early 1900 for ice houses and dairies.
Likely one of the better choices at the time but we have better options today.
https://news.stlpublicradio.org/other/2009-03-23/fire-destroys-building-at-historic-dairy-complex
Walta