Could an old practice be the future of home insulation? 

Patrick Crabbe, a housing specialist who works in Bedford, N.S., is trying to be patient.

“Like I said, I don’t think that’s actually a thing,” he says.

I persist. “But it was … you know … once upon a time. I mean not too long ago, people would go down to the beach and scoop it up by the bucketful, right? Right?” 

I was vaguely aware that I sounded strange. The week before, faced with an encroaching Halifax winter and increasingly decrepit attic, I had decided to find a cheap and environmentally responsible solution to my insulation problem. My neighbour, who once owned a hardware store, suggested seaweed. He said it was all the rage back in the 1930s (that other time when nobody had any money) when my house was built. 

“People would haul it up to their homes or cottages or shacks or whatever and stuff it into their walls,” I tell Crabbe. “Presto … instant insulation … free … courtesy of Mother Nature.”

He’s diplomatic. “Maybe, like, on a very unique, residential scale,” he says, which I believe translates as: There’s nothing special about insulating your home, you fool, especially nowadays … Now, please go away.

Of course, he’s right. 

Given concerns about climate change and affordable housing, the federal government’s Canada Greener Homes Grant is providing 700,000 bursaries of $5,000 each to homeowners who want to make their places more energy wise. Trades have been meeting demand both for polyurethane spray foam and more ecologically hospitable alternatives, including: wool, denim, bark, and cork batting and panels. 

In Atlantic Canada, our environmentally friendly preferences still tend to run in the mainstream. Efficiency Nova Scotia, for example, lists rolls and loose fill made of recycled fiberglass and powdered basalt among the most popular choices. Companies here also offer a castor oil-based spray foam called lcynene.

Costs and R-values (heat transfer rates) vary. Insulating my attic with fiberglass batting, for example, might set me back $2.50 a square foot (including labour) and improve my overall energy efficiency by 25%. If, however, I went for lcynene (“ice-uh-neen”)—a 35-year-old Mississauga invention now under the wing of a Quebec-based building supplier—I might retain a bit more heat for a bit more money. 

As for wool, denim, bark, and cork? 

In Atlantic Canada, our environmentally friendly preferences still tend to run in
the mainstream

“What I am aware of for a potential alternative insulating material here is wood fibre,” says Crabbe, who is national mass timber manager for Bird Construction and the former program director of the Maritime Lumber Bureau. “This would be quite attractive in Nova Scotia (where) there is a lot of chip waste for making paper … (But) we have no manufacturers of this, and it’s really only in its infancy in Europe.”

Fair enough. But here’s what isn’t: seaweed. 

In a 2013 article for Wired magazine, contributor Joe Flaherty explains why a particular algae-covered house in Denmark was “the world’s coziest sushi roll.” Noting that the cottage on the island of Læsø in the North Sea “draws its unique feature not from scientific advance, but from the era of Viking sagas,” he described “the array of cylindrical, seaweed-stuffed ‘pillows’ on the façade” and the plant-infused walls. 

According to the project’s manager, Jørgen Søndermark: “The idea is to revive interest for the unique tradition of seaweed thatching and in a broader sense re-introduce overlooked or disregarded organic materials at a time where low-carbon solutions are much called for.”

He isn’t alone. 

Due south, near the Mediterranean Sea, Germany’s Fraunhofer Institute for Chemical Technology has been converting little globs of dead seaweed, called Neptune balls, into useable insulation. 

According to a 2013 report in New Atlas magazine, the material is “mold-resistant, almost completely non-flammable, won’t rot, and doesn’t require the addition of any other … It can also absorb water vapor and release it again, without compromising its own insulation value.”

What’s more, neither endeavour was an experimental lark. Both had business plans, private investors and government money behind them. After all, nobody ever dreamed that a bunch of interlocking plastic blocks would one day become the biggest thing in global toy land. But as the seaweed house’s lead architect Søren Nielsen said, “There is a reason that Lego is a Danish invention.”

Still, if they can do it, why can’t we? In fact, there’s precedent for this on the Canadian East Coast. 

According to a Maclean’s article, published in 1947, “Since the autumn of 1945, when the industry was revived after a lapse of 15 years, 45 tons of Seafelt [seaweed] have gone out of [a] plant at Sable River, N.S., each month. Nowhere else in Canada is this type of insulation made. Few Canadians know that it is the oldest type of commercial insulator in the world, and one of the most efficient. Most of it has been grabbed up in the Maritimes, but when production increases, it will be available to the rest of Canada.”

Could seaweed be the comeback kid of home insulation … again? 

Crabbe and undoubtedly scores of others who know far better than I about these things would argue that you’d need infrastructure, machinery, innovation capacity, and all that jazz to make it work. So, no, it’s not actually a thing. 

But I can’t stop thinking about that hole in my attic (and my budget) and all that lovely, free seaweed just gathering flies along Atlantic Canada’s various ocean playgrounds.

“You do know I was pulling your leg,” my neighbour smiled after I reported the results of my research. “But you can borrow my truck if you want.”