Modern Seaweed House harkens back to Danish homes of yesteryear


August 1, 2013

The Modern Seaweed House was constructed with timber-frame panels and stuffed with seaweed as an alternative insulation to mineral wool

The Modern Seaweed House was constructed with timber-frame panels and stuffed with seaweed as an alternative insulation to mineral wool

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Joining the ranks of homes built with edible materials, such as the Tourner autour du Ried, made using corn cobs, and the Mushroom Tiny House, built with (you guessed it) mushroom-based products, is the Modern Seaweed House. Located on the small island of Læso in Denmark, the house features a simple wooden structure covered with an insulating layer of seaweed.

Danish architectural firm Vandkunsten partnered with non-profit organization Realdania Byg to create the holiday home. “The idea was to re-introduce an overlooked or disregarded organic material into a modern industrialized technology during a time where low-carbon solutions are much called for,” senior Vandkunsten architect Soren Nielsen tells Gizmag. “The objective was to demonstrate how a natural resource like seaweed can be integrated into a contemporary construction practice and put to an ordinary use.”

Although the idea of using seaweed to insulate and protect a home’s structure is unusual today – although it could soon prove more popular with Fraunhofer researchers having created building insulation from the plentiful material – the Vandkunsten architects were not the first to come up with the concept.

Seaweed homes were once a common sight on the island of Læso and during the 19th century several hundred of these homes could be found there. Today, however, only around twenty of the original seaweed homes remain, serving as a reminder to part of Denmark’s unique architectural history.

“The seaweed houses on Læso are physical testimony to the culture and the life that have characterized the building tradition on the island for centuries,” says Peter Cederfeld, managing director of Realdania Byg.

It is important to note that the Modern Seaweed House is not merely a copy of the traditional seaweed homes but a new contemporary and sustainable home inspired by the idea. The 100 sq m (1,076 sq ft) home was built for two families (eight occupants) and includes a large central family room with kitchen. At both ends of the house there is an additional living space that features a raised loft bed for additional guests.

It was constructed with timber-frame panels and stuffed with seaweed as an alternative to mineral wool. The roof and facade were then cladded with pillows made from knitted wool and stuffed with seaweed. On the roof these pillows are thick and soft, while on the facade they are small and hard, resembling brick work. Furthermore, the peaked ceiling is also covered with panels stuffed with seaweed and upholstered with linen fabric.

“The focus on the use of the seaweed material, together with the wooden construction, can bring the carbon-footprint down to a very low level,” says Nielsen. “The energy used for operation is very low in the seaweed house due to passive measures such as high insulation thickness, airtight assembly, heat recovering system, heat-pump, and low-energy windows. The house lives up to the strictest standards for low-energy buildings in Denmark with an expected consumption of 20 kWh/year/sq m.”

Despite being built with a remarkable amount of seaweed, the home is expected to have the same lifespan as any other conventionally-built structure. There is also no specific maintenance required as a consequence of the seaweed components.

“The seaweed material is extremely robust as it does not rot, mold or attract pests,” says Nielsen. “However, over time we expect plants and birds to inhabit the roof as part of its weathering. To ensure the technical quality of the roof there is a dense layer of roofing felt below the seaweed thatching.”

Nielsen’s personal favorite aspect of the home is the exterior cladding which most explicitly displays the seaweed. “There is warmth and a sense of pre-industrial humanity in the furry and imprecise outline of the elements, paradoxically produced in an industrial process,” says Nielsen.

The Modern Seaweed House cost €268,000 (US$345,000) including land purchase, however, the architects anticipate that a similar home could be built on the mainland for ten percent less.

Source: Vandkunsten, Realdania Byg via Dezeen

About the Author
Bridget Borgobello Bridget is an experienced freelance writer, presenter and performer with a keen eye for innovative design and a passion for green technology. Australian born, Bridget currently resides in Rome and when not scribbling for Gizmag, she spends her time developing new web series content and independent cinema. All articles by Bridget Borgobello

Wouldn't the seaweeds leach salts into the structure? Not necessarily damaging (except perhaps to steel fixings such as nails or screws- would need to be stainless steel). but it would be a bit of an eyesore.

Otherwise a very interesting project.


I guess it will cost a lot green to go green. I wonder how many would be able to afford it? It is still cool despite the cost.


$350,000 for a 1000 square foot house seems like a very, very expensive house. If this does not include cost of land but just construction cost than going green is only for the wealthy.


A few technical details would improve this article for other audiences-such as the R value per inch of seaweed, wall thickness, insight into why so many doors? Climate data: temp in summer, winter? and, what does it smell like when wet? Thanks David


The seaweed is poorly placed for insulating purposes. I have trouble taking seriously people that seem to think This is great stuff lets use it poorly.


This article is so lacking in useful information. Perhaps this is a good idea, perhaps not. 345k including the land?? well how much is just the house.. I mean the land could of been 1k or 200k??

1k Sq foot for 8 people? What is this Tokyo? India? Thats a small place for 8 people in US standards.

I love the idea of alternative building materials, but this almost seems silly. Sea weed grows fast, but so does bamboo, thatch and other grasses.. Why is sea weed a better materials?

I want to know more but so far this seems like a non-starter.


Like the others noted - seems very expensive, even factoring in land cost. Why cannot these architects/designers ever come out with projects costing under half that price? Even if mass production of the seaweed packets brings their price down, it surely will not be a tremendous reduction, and then there will be the supply/demand problem.

The Skud

I think 'wet seaweed' and one thing springs to my mind. The smell...


"Sea weed grows fast, but so does bamboo, thatch and other grasses.. Why is sea weed a better materials?"

Perhaps because of its island location, and a ready local supply of kelp!

David Bell
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