Traditional Danish seaweed thatching could be updated into a sustainable contemporary building material, according to research by Kathryn Larsen.
Copenhagen School of Business and Design student Larsen became interested in the potential for seaweed architecture after studying the Viking practice of thatching roofs using eelgrass on the island of Læsø.

"Eelgrass is a fantastic material that is naturally fireproof, rot resistant, carbon negative and becomes entirely waterproof after about a year," said Larsen. "It also insulates comparably with rockwool [a common type of insulation]."
"Plants grow in it, giving the effect of a green roof. It is a material that we should be considering seriously in an era of climate change."
A student of the Material Design Lab at the Copenhagen School of Business and Design (KEA), Larsen went on to test what a contemporary iteration of seaweed thatching might look like.
She tried different binders and grid spacing, eventually developing a set of prefabricated eelgrass-thatched panels to suit roofs or facades. Colloquially known as a seaweed but actually a type of seagrass, eelgrass is common across the UK and Scandinavia.
Larsen notes that while eelgrass levels are diminishing, there would be enough to supply a Danish construction industry, and that there are ways to farm and harvest the plant without harming the marine ecosystem.

She drew on the results of a 2013 project, The Modern Seaweed House, built on...