Eelgrass

Eelgrass

BioSack

BioSack came to life with the idea of only using materials within reach (so to speak) like the traditional houses built on Læsø. The roof construction was made of driftwood, birch branches and eelgrass, with the possibility of adding more eelgrass to the roof over time to make it last longer. These roofs have now been standing for hundreds of years.
Like trees, the eelgrass absorbs and stores carbon while growing. When reaching a certain length, it detaches from its root system leaving it to tangle with nearby eelgrass drifting towards the coasts. Lumps of eelgrass wash up on land and are then collected/harvested and spread across the nearby field by the farmer for drying. When dry enough the eelgrass is compressed to round bales to be stored.
Ensuring a minimum amount of used eelgrass, the timber frame of the pavilion has been added woven net in the shape of a basket/bag, making it possible to shape the top of the pavilion as wished. The self-made net is woven from sisal rope which in general almost functions as a magnet to the eelgrass – it really wants to tangle with both itself and the sisal rope. The net is made of 15x15cm masks which could have been larger due to the capability of the eelgrass tangling around itself. Originally on Læsø when finishing the roof of eelgrass, potato plants would be thrown at the eelgrass leaving the potato to put down roots maintaining the very top of the more exposed eelgrass. Today turf grass rolls are rolled out on the roof ridge.
The floor of the pavilion is made from seashells contained by the surrounding wooden frame. The idea of putting seashells on the deck is to create a barrier between staying outside of the pavilion and staying inside the pavilion. The transition of moving from the outside to the inside creates an instant focus on the material the visitor is crushing when walking on it. It puts a focus on the floor of the pavilion to leave the visitor even more surprised and affected when afterwards looking up into the shape of the wooden frame and the hanging and heavy-looking eelgrass. Furthermore, the floor of seashells has shown to be a very good social icebreaker in terms of people interacting with one another as well as sharing the knowledge of how seashells perfectly can replace the huge amount of polystyrene as an insulation material in the building industry.

The design of the wooden structure and the joints has come from inspirations from both the half-timbered constructions of the old Nordic architecture as well as the Japanese way of working with wooden constructions and joints.
The idea of the wooden frame has been with the two focus on reuse and assemble to disassemble – as many times as wanted. The wooden frame consists of glue laminated timber from a social housing project of rowhouses near Odense, which had to be taken apart due to moisture accumulation in the foundation. Stark Gentræ is a newly started project, collecting materials from projects that are to be demolished/taken apart. Stark Gentræ has been the generous provider of the materials needed for the structure to give the impression as wanted – a secure space to e.g., have a significant talk inside – as an important view on social sustainability. The timber was then cut and tapped to create the different joints.

The social housing company, Civica, has shown their interest in buying back the pavilion for the large park in the same social housing project that the timber comes from. Now the houses have been rebuilt for the same vulnerable families to move back.

Ingredient list

Eelgrass/seaweed, seaweed insulation/acoustic batt (compressed), reused wood, seashell, sisal rope, metal rod, potato plant

Maker

Rex skov arkitekter

References

Chart Art Fair pavilion features a seaweed roof | #Shorts | Dezeen (Video)
Tangtage - byggefilm (Video)
Rex Skov Arkitekter tops Chart Art Fair pavilion with seaweed roof (Article)

Credits

Stark Gentræ, Søuld, Vilsund Shells, Antidark, Melbjerggaard Vegetables

Photo credits

Joakim Züger/Barks Projects, Andrew Berekdar / Tepee Films / Dezeen