Paint doesn't insulate!
Don't buy the hype about insulating paint, it doesn't work. This is snake oil in its truest form.
No matter that engineers and architects long ago debunked it, insulating paint still occasionally finds its way into buildings. Powdered ceramic chips that can be added to any paint are said to reflect heat in or out of a building and reduce heat loss by staggering amounts.
I was under the impression that this had been successfully exposed as a fraud, until a mention of it recently came up. All it took was a quick Google search to find a supplier more than willing to extole its virtues. So it's still out there, and clearly in need of a fresh rant.
The claim that powdered ceramic paint additives can reflect heat isn't the big falsehood here, but rather the rate at which it does that is beyond suspect. There may be some value in it's ability to reflect heat away from a building when applied to the exterior, though there are many sensible alternatives that for sure work.
The big ruse here is when it's promoted as an alternative to insulation when applied to the interior of a building, or that it can double the R value of an existing wall. It may add an inconsequential decimal point of R value to your wall, but that is akin to a butterfly slowing down a passenger train in an impact. Yes, the butterfly collision *will* slow the train, but not so much that the jolt will make you spill your coffee or get whiplash. Including insulating paint in your wall assembly will have a similar effect on your heating bill.
The attic of insulating paint sales rep Alton King, where the only 'insulation' included was paint. Image via Green Building Advisor
Like so many things, fringe building products that sound too good to be true usually are. If paint insulated walls then why not forgo insulation all together and just put about 3 coats and call it a day? Or 5 coats and call it a Passive House? Because that nagging little voice in the back of your head is right; you are being sold a bill of goods and you might as well buy actual snake oil and apply it to your walls for all the good the paint will do.
One account found on Green Building Advisor tells of a company sales rep so enamoured with his own product that not only did he ignore that inner voice, but he built a monstrous 7,200 square foot house without insulation, relying entirely on his magic paint instead. Needless to say, even with heating and cooling going full blast, he froze in the winter and cooked in the summer. That's karma for you I guess.
Sorry to sound so flippant about it but it really grinds my gears to see good people getting fleeced of their money and thinking they've solved a problem when they haven't. Not only do they get their pockets picked, but they risk seriously screwing up their houses because they think they have insulation and they actually don't.
Insulating paint often finds its way into a build when there is insufficient space to build properly, so it's sometimes found in container houses and tiny houses as well. People living in homes without proper insulation or the money to undertake a proper retrofit can also fall victim to this scam, and after dropping $100 or more per can, they are only further away from having the money to effect a real solution to their insulation problems.
image via Ebay
Dealers of insulating paint are very quick to name-drop NASA and talk about heat-reflection during space shuttle re-entry, but don't be dazzled by this nonsense. Yes, the technology originated there but its value ended there as well and NASA was not involved in any way with paint products in the residential housing market.
Suppliers will also drop a bunch of figures about how it doesn't directly add R value but, by reflecting heat, the paint offers an effective 'boost' to the R value. And they include some very convincing sounding stuff about heat transfer and thermal resistance for good measure, including the percentages of heat that you will save off your current bill. This is not the first time that the laws of physics have been cherry-picked to spin a good yarn, nor will it be the last. Such narratives are usually packed with impressive claims, confusing calculations and real or imagined terminology, and it works great.
In fact, it has been conclusively shown that 67% of people will believe randomly made up statistics, and that number jumps to 72.58% if you include two decimal points.
So that's all I have to say on this since the voodoo science behind it has been debunked many times over. For more details about the claims and the realities of this, here are the conclusions of some of the respected names in the building information community:
- "While these products may have some relevance in the extreme conditions of outer space, manufacturers of paints containing [insulating additives] are making claims that defy the laws of physics." - Alex Wilson
- "There is poetic justice to a story in which a distributor of “insulating” paint ends up shivering during the winter and sweating during the summer because of the ineffectiveness of his worthless paint." - Martin Holladay
- "Everything I ever learned in Architecture School and practice tells me that this is impossible." - Lloyd Alter
- "If this paint is really equivalent to R-24 batt insulation, why in the world would we put any insulation in our walls at all?" - Jon Eakes