So to make these roofs several tons of Zostera had to be take up from the Kattegat, dry it and place it on the rafter. To tie it to them ropes were made to hold it to them. On the roofs you can see flowers growing.
To insulate the houses they were covered with turf too so they were warm in the winters.
Around 1900 most of all houses had Zostera roofs, today only 19 are left, 11 of them are protected by law.