Nice photo!
Turf roofing was the old way to do roofs in Norway. Still used today, but now it is exclusive.
They old roofs have many advantages. Relatively free of cost, except from the labour...
Insulation is excellent too. Much needed in the Norwegian winter.
And of course it would give a little extra grass for a sheep or a goat.
thanks a lot for you coment! it's really interesting to know