Here’s a thought! Amazing what you stumble upon – apparently seaweed houses have been a traditional method of construction on some island communities. A modern take on it is on Dornob. Click here for more information. Pictures of the seaweed house at the bottom of this post.
So many ideas for building in Fiji where timber is expensive. Funnily enough though, mahogany or mangrove wood is used for firewood here, and the sawdust from the mahogany is sold for $2 FJD per bag to use in chicken houses or on the garden. Banana crates are made from mahogany, but most Fijian homes are made of either concrete or corrugated iron. So many of the homes even in coastal villages are corrugated iron loosely cobbled together. So many (between 100,000 and 300,000) people in Fiji live in informal settlements or shanty towns. http://www.informalism.net/2010/04/asian-coaltion-for-housing-rights-in.html
Seaweed is apparently fire resistant and insulating, and also readily available in Fiji.