Before there were Home Depots, people used what was around them, and builders got very creative with indigenous materials. On the island of Læsø in Denmark, they had a lot of seaweed. It appears to work well and last a long time; one dates back to 1865.
Now Realdania, a Danish architectural preservation society and trust, has built a new seaweed home. This is unusual for such an organization, but their mandate includes construction of buildings with "significant experimental character with respect to architecture, technology, or location."
Seaweed is at the same time very old and very 'just-in-time', because it is in many ways the ultimate sustainable material. It reproduces itself every year in the sea, it comes ashore without any effort from humans, and it is dried on nearby fields by sun and wind," he continued. "It insulates just as well as mineral insulation, it is non-toxic and fireproof, and it has an expected life of more than 150 years!
The exterior of the house is clad in bolsters of knitted netting. Looking at the closeup, one has to wonder how it sheds water, and the project manager explains in comments on Dezeen:
The seaweed does not swell as such when it rains; it will be wet though. In the beginning all the way through, but later on we expect the seaweed to form a layer that stops the water, as it does in the old seaweed roofs that you find on the island of Laesoe.
Inside, the walls are made of prefabricated cassettes and insulated with seaweed, while the ceiling is padded with seaweed behind linen, which will make for wonderful acoustics. According to the press release:
Besides its excellent insulating property and long-term durability, which in itself offer a lot of potential, it has been discovered through practical application that seaweed has exceptional acoustic properties. This creates surprisingly comfortable rooms while the ability to absorb and give off moisture contributes to regulate a good indoor climate. The numerous qualities provide a wide range of applications in modern, sustainable building.