Eelgrass for insulation and rooftops

With an overall Cradle to Cradle GOLD certification, insulation mats and roof ridges for thatched roofs made from eelgrass is the best sustainable products you get.


Historically eelgrass that floats to the shores in the autumn storms has been used for thatched roofs on the old houses on Laesoe. The roofs are extremely sustainable, the insulation value of eelgrass is comparable to that of mineral wool, it is not contaminated with fungus and last but indeed not least: it cannot burn.

All of these qualities was the impetus to seek means for developing an insulation mat and a roof ridge for thatched roofs. In co-operation with Convert and the help from a public fund, both the insulation mat and the roof ridge is developed and accomplished fantastic Cradle to Cradle certifications.

View the Cradle to Cradle certification for the seaweed insulation mats.and the seaweed roof ridges


The market for both products is big. Sustainability is on the rise within the building industry, but right now the challenge for Zostera is the gathering and the price of the eelgrass.

– Even if the material is a natural resource, the gathering of eelgrass is a slow and costly process. And as eelgrass hitherto has only been used commercially for the restoration of the few seaweed houses on Laesoe, the gathering has not been streamlined, Kirsten Lynge explains.

This process is part of the ongoing work in Zostera. Kirsten Lynge and Gunnar Agerskov Madsen hope that eg. municipalities with shorelines, who nowadays pay to get rid of the eelgrass, see a better use for the natural resource as part of sustainable products.

– Actually, eelgrass releases a lot of CO2 when it lays rotting on the shore. When used for insulation mats or roof to ridges, it does not. That is another strong case in favour of using eelgrass for lasting products, Kirsten Lynge says.

Read more about Zostera.