Healthy Homes: Four Natural Insulations

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At the heart of all healthy homes has to be green insulation. It’s how we save energy, keep cool in summer, warm in winter, and keep ourselves breathing easy.

The trouble is, where to start? What’s the best “green” insulation?

It’s probably safe to say that the home-insulating industry has only really begun thinking outside the box in the last few years. If you decide to do some research, make sure you’re looking at information from the 2005 and on, since there have been so many advances this past decade.

Some positions are changing, like this article stating how the sprayfoam insulation industry continues success amidst growing concerns about its safety, from whether it’s made with safe products to its ability to age well without deteriorating.

Thankfully, insulation options for healthy homes are far greater than just old-school fibreglass insulation versus sprayfoam, and I can’t wait to see what other options unfold in the years ahead.

Let’s look at a few options that both keep you warm and dry, but also breathing easily.

Mighty, Mighty Mushrooms

An incredible development means we might just see homes insulated with mushrooms in the future. Well, mycelium, derived from mushrooms. As this report explains, “Although they call it “mushroom insulation,” you’ll see no mushrooms sprouting from the walls. The substrates used as the filler material that the mycelium feeds on and weaves together are sterilized to prevent other organisms from growing. Then, once the mushroom insulation has finished growing, they hit it with steam to stop the growth.” Right now, you’ll need thicker insulation and thicker walls to get the same R-value protection offered by other insulations, but this product is young and, forgive me, is fertile ground for innovation and growth.

Sheep’s Wool

Not just for sweaters anymore, sheep’s wool insulation is completely natural. If wool catches fire, it burns itself out, since it doesn’t support combustion, making it as fire-safe for homes as can be. The science? “Wool has a very high inflammation point of 560°C due to its high Nitrogen content of ~16%.” Since there’s very little messing about with the natural product, it’s very “green” to make sheep’s wool insulation. It absorbs up to 35% of its weight in water without affecting its ability to retain heat, and has high natural elasticity that means it won’t lose performance over time. Its R-value is between R-3 and R-4 per inch of thickness. Not too shabby there, sheep.


Denim is one of the planet’s most popular clothing looks, thanks to its durability. But when your jeans finally give up, what next? With a world market of well over $55 billion in jeans selling a year, the recent trend of turning scrap denim into recycled cotton insulation makes good enviro-friendly sense. Cotton’s great at absorbing moisture and it can be made fire-retardant with a boric acid treatment. It’s still a pretty expensive option compared to fibreglass, but it offers a lot of the same benefits and is installed much the same, since it’s made into rolled batts. Cotton insulation doesn’t cause respiratory issues and has the added benefits of being a good insect repellant. It bugs the bugs? Gotta love that.


First used as insulation by accident 120 years ago, cork’s making a comeback thanks to folks like the founder of BuildingGreen using it for his net-zero home. Cork insulation, he wrote, “contains nothing but cork— nothing! 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.” Cork itself is a sustainable product because it can be harvested from the “cork oak” without damaging its tree. Aside from its great insular properties, it also dampens sound, not a bad thing when you’re going for peace and quiet at home.

But wait, there’s more

It’s an exciting era because we’re constantly learning more and more about the world around us, enabling us to better use Earth’s natural products for modern purposes. There’s more we can do, too. From the way we design our houses to the places we put them, through to the products and techniques we build and maintain them with, we’re able to make homes healthier than ever before. Stay tuned as we keep talking about this important topic in future installments of our Healthy Homes Series.


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Steffani Cameron

Steffani Cameron is a Victoria BC-based writer on a variety of topics. Here on the BuildDirect blog, she specializes in writing about smaller, urban spaces. How do you make the most of your smaller space? How do you decorate it to suit you? And how do you wage the war against clutter and win? This is Steff’s specialty.