Søuld’s eelgrass products originate from the sea—a place you are never far from in Søuld’s native Denmark. The organic material embodies the same sense of calm provided by the sea and when taken indoors, it imbues living spaces with a restorative connection to nature.

AN OVERLOOKED RESOURCE — Eelgrass’s use in construction dates back to the 1600’s, when settlers of Læsø island would forge thick roof-thatching for their ‘seaweed houses’—a technique unseen anywhere else in the world. Enhanced through state-of-the-art technology, Søuld’s work represents a passionate reinvention of Denmark’s forgotten seaweed house heritage.

After a decade of research and development into the material, Søuld has emerged as an expert in eelgrass and is the first company to convert the material into CO₂-storing building materials that combine high acoustic performance, safety and durability with sustainability and modern aesthetics. Working together with local farmers, municipalities and ecologists, Søuld has optimized eelgrass collection based on environmental protection and the preservation of natural eelgrass meadows.

The CO₂-binding sea plant is found washed ashore along Denmark’s coastline as an abundant, renewable and overlooked local resource. The plant absorbs significant amounts of CO₂ while growing in the sea and therefor serves as a carbon sink when used in construction.

Søuld has demonstrated that this natural, non-toxic and CO₂-binding material has numerous inherent qualities as a modern building material: it dampens noise and provides exceptional acoustic comfort; it absorbs and releases moisture without rotting to create a healthy indoor climate free from bacteria, mould and other microbes; it features great thermal insulation abilities contributing to a smaller energy footprint and a comfortable indoor climate; and due to the plant’s natural salt impregnation, the material resists fire and has an expected lifetime of more than 150 years.



To unlock the benefits of eelgrass, Søuld has spent over five years devising manufacturing processes that merge nature with state-of-the-art technology, and has built a local community of dedicated eelgrass suppliers. 

OUR PROCESS — Søuld has established the optimal formula to produce eelgrass mats at an industrial level and deliver products that meetmarket needs, and has validated the material’s characteristics to the design and construction industry.

Søuld’s products are responsibly manufactured in Denmark through close, long-standing relationships with local partners who are equally committed to quality, sustainability, and to producing materials with lasting value. We ensure that all materials meet the highest standards with respect to toxic emissions. We only use compounds that are manufactured without noxious chemicals and release no volatile organic compounds to the indoor environment.

Søuld’s products and processes are designed to be fully circular and with the lowest environmental impact possible. We see it as our responsibility to protect the environment and the health of producers and customers We therefore require the same environmental commitment from our production partners and provide full transparency about our materials, processes and product life-cycle.



1. SOURCING — Eelgrass is a natural resource which reproduces itself annually in the sea, washes ashore without any human intervention, and is dried on nearby fields by the sun and wind. Working closely with our community of farmers in Denmark as well as local municipalities and ecologists, Søuld has developed a responsible approach to eelgrass collection based on environmental protection, safeguarding of ecosystems and the preservation of eelgrass meadows. Our sourcing practices also sustain the age-old eelgrass trade and empower local businesses. 



2. AIRLAID — At Søuld’s Danish production facility, the eelgrass is analyzed, sorted and classified according to colour and quality, then shredded down to shorter standardized fibres to ensure the best aesthetic and mechanical properties. Initially, the shredded fibres are impregnated with a natural, non-toxic flame retardant and mixed with a binder specially designed for cellulose fibres and recyclability. The blended fibres are then formed into eelgrass batts using airlaid technology. 




3. COMPRESSIONAfter the fibres are formed into eelgrass batts, they are compressed into mats using a process which balances a low temperature with high compression. The mats are then ready to be cut. Standard sizes are offered at 600 x 1100mm, or the mats can be fully customized to suit any project, with sizes up to 3000 x 1100mm. The finished mats are then ready for easy installation onto interior walls or ceilings. 




4. CIRCULARITY — Søuld’s products are designed for circularity. When they reach their end-of-life after many years of use, they can be returned to the factory, re-shredded and either blended into standard products or used to create a base for second-generation Søuld materials. This process ensures the products’ sustainability throughout the entire life-cycle. Søuld products that are not returned to the factory can be sent for combustion at heating plants. 




5. QUALITY CONTROL — Working with local production partners, we ensure full control over the quality of every component as well as the final product. Nothing is overlooked—Søuld checks every single mat repeatedly on its journey and tests samples for the optimal properties. We constantly fine-tune the aesthetic and mechanical properties of our mats to deliver the best sustainable option for architectural applications.

Quality Control


6. TRANSPARENCY — Our materials are responsibly sourced and produced in Denmark according to the highest local environmental standards and industry certifications. As a manufacturer we make every effort to maintain transparency about the materials we use, our processes and product life-cycle. We strive to further reduce any negative environmental impacts from our production, and to replace our secondary materials with even more ecological alternatives based on the latest research. 




Søuld’s eelgrass products are the result of a passionate reinvention of a 400-year-old Danish tradition that casts an ancient material in a new, modern light. 

MATERIAL HISTORY — During the 1600’s, on the remote Danish island of Læsø, locals developed an ingenious building solution. In a landscape with scarce resources, Læsø’s settlers turned to the salty seas where the eelgrass plant grew in a soft underwater fringe that drifted ashore after autumnal storms. Thanks to the water’s high salt content, the eelgrass thrived in this otherwise desolate climate and offered an easily accessible, free and abundant material for the growing population of salt makers and fishermen to shelter their homes with.

While the men were fishing out at sea, the roofs were built by women who resourcefully applied their weaving skills to construct the eelgrass thatching. Driftwood salvaged from shipwrecks was used as timber and the eelgrass was collected from the shores, harvested, dried and woven to form thatching. The incredible durability of the roofing resulted from the eelgrass’s natural sea salt impregnation which makes it resist decay, as well as through the solidification of the mass over time which resulted in a waterproof barrier. The material also provided the homes with inherent fire resistance and insulation.

By the beginning of the 20th Century, most Læsø homes were thatched using eelgrass—amassing around 250 examples of this natural ‘seaweed house’ technique. During the 1930’s the tradition was abandoned due to changing construction demands, and eelgrass was forgotten until recently when a community of local craftspeople uncovered it. The group carried out experiments with Danish farmers from Møn and Bogø, learning how to collect and dry the fresh eelgrass to obtain the desirable qualities. 


In 2009, a team of ecological entrepreneurs partnered with philanthropists and The National Museum, The Danish Heritage Agency and The Realdania Foundation to establish Læsø Tangbank—a project dedicated to the restoration and protection of the remaining 36 seaweed houses and to the renewal of the eelgrass material trade the houses rely upon. 

Through their work, Læsø Tangbank unearthed a rich archive of building methods, worked closely with local farmers to develop efficient eelgrass harvesting and manufacturing methods, and raised awareness of the material’s excellent building properties. In 2016 Læsø Tangbank became Søuld, which now operates with a decade of expertise in eelgrass and a deep commitment to its potential in sustainable construction. 

Today Søuld is focussed on enhancing and modernizing the time-honoured eelgrass material through state-of-the-art science and technology, while preserving an important aspect of Danish cultural heritage. Søuld is on a mission to re-introduce the remarkable but overlooked material at a time when low-carbon building solutions are vital for the preservation of the environment. Over the years, Søuld has revived Denmark’s old tradition of harvesting and drying eelgrass, developed practices to safeguard the eelgrass ecosystem and the continuous preservation of this natural resource. Søuld has built a growing network of specialized eelgrass suppliers and optimized the raw material production to ensure high quality and performance.


Material          Production          History


Architectural materials made from eelgrass for healthy and environmentally friendly living.

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