ABC Wednesday, S, Scandinavia,Sod roof .

The first time I visited Norway I saw these remarkable houses covered by grass roofs. I was fascinated by the look of them. A long time before, I had met a Norwegian young man in one of the workcamps, where we worked during the holidays as volunteers. He told me a lot about Norway and also about the grass roofs. He said that some farmers put their goats on top of the roofs to keep the grass short and to prevent trees from growing on the houses.

Maihaugen in Lillehammer

Valdres Folkemuseum

Valdres Folkemuseum

"A sod roof or turf roof is a traditional Scandinavian type of green roof covered with sod on top of several layers of birch bark on gently sloping wooden roof boards. Until the late 19th century, it was the most common roof on rural log houses in large parts of Scandinavia.

 The load of approximately 250 kg per m² of a sod roof is an advantage because it helps to compress the logs and makes the walls more draught-proof. In winter the total load may well increase to 400 or 500 kg per m² because of snow.

 The birch bark underneath ensures that the roof will be waterproof.

The term ‘sod roof’ is somewhat misleading, as the active, water-tight element of the roof is birch bark. The main purpose of the sod is to hold the birch bark in place. "( Wikipedia)

.A sod roof has a lot of advantages: Firstly it is cheap, for the materials used for it, like birch bark and grass turf, are available in abundance.
Secondly: It's an ideal way of insulation in the cold and long Scandinavian winters.

But it requires a lot of time! No problem, for neighbours and friends are invited to join in a roofing party

History

Sod roofs on farmhouses in Gudbrandsdal, Norway. Photo: Roede.

This practice of covering roofs with birch bark and grass sods in Scandinavia, dates back to prehistory. The Vikings and People from the Middle Ages built their houses this way.This lasted until the beginning of the 18th century. Gradually houses in towns were built with tiled roofs and sod roofs almost disappeared, This was considered to be a threat  to ancient traditions. This caused a general revival of vernacular traditions, including these sod roofs.

Maihaugen

Mountain lodges and holiday homes with sod roofs became very popular. Open air museums like Maihaugen in Lillehammer, and reservations all over Norway, contributed to a better knowledge of the ancient culture of Norway and the rest of Scandinavia.

Røros, old mining town

Røros, old mining town.

 Isn't it wonderful to have flowers on your house?

From these reservations, sod roofs have begun to reappear as an alternative to modern materials. The more recent idea of the green roof is developed independently from the traditional sod roof, but could benefit from the experience gathered during hundreds of years in Scandinavia.

Birch bark

Doukhobor house in Yefremovka, Georgia, with a sod roof.

Birch bark is important for a sod roof, for it is strong, water-resistant and soil-resistant enough to last for generations, although 30 years was considered the normal lifespan of a sod roof in most places. Birch is common everywhere in Northern Europe, and its bark is easily stripped from the trunk in spring or early summer, while the sap is running.

"Bark has to be weighted down with a heavier material to prevent it  from curling or blowing away. Therefore sod is used and this  has an additional advantage because it is an insulator.

 The first layer of sod was traditionally placed with the grass down, as the wilted grass would protect the bark from acid humus and act as a drain. The grass of the second layer faced upwards to establish a solid surface. Grass roots would eventually permeate the bottom layer to create one solid structure. The finished roof would in time look just like a flower-studded meadow. "( Wikipedia)

With thanks to Denise Nesbitt,  who created ABC, and Roger, who took over from her. For more interesting ABC posts click on the logo in the sidebar. This week we are looking for words beginning with  S.