What is a sod roof?
A sod roof (also known as a turf roof) is a method of roofing using layers or birch bark covered in sod, which is grass with the soil beneath it containing the roots. 
What is the history of sod roofing?
A sod roofing is a traditional method of roofing in Scandinavia. Until the late 19th century it was the most common roof on rural log houses in Scandinavia. The weight of a sod roof is 250 kg per metre squared. This weight is an advantage as it helps to compress the logs and makes the walls more draft proof. In winter, this weight increases due to levels of snow fall. The birch bark underneath the sod ensures that the roof is waterproof.
Building a sod roof
The main element of the roof is birch bark, which is held together by the sod. The materials are all natural and easily found in rural areas, which makes it suitable for its surroundings. Putting together a sod roof is labour intensive and requires a lot of manpower. They are usually completed during a roofing party where neighbours, family and friends all take part in.
Birch bark is water resistant, soil resistant and strong, making it perfect for making a sod roof. It is easily cut and can is commonly found in Northern Europe. When the sheets of bark have been cut, they are stored flat under pressure to prevent it curling, which if left naturally it would do. 6 or more layers of the flattened bark sheets are then laid from the eaves upwards, ensuring that they are overlapping.
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| Traditional sod roofing method, including a turf log which is held by wooden hooks |
Sod is cut from good quality land with sandy soil with a deep root. Small pieces are cut for easy transport and then taken onto the roof and laid. Sod must be laid out immediately after the birch bark to keep it in place, which means that the whole process must be accurately timed and coordinated. The finished roof must be between 15cm and 20cm because the sod has to have enough water to survive a dry summer, but not too much as the weight would be excessive.
Today, sod roofing has been adapted to our modern ways of living and is now referred to as 'green roofing.' Germany, Switzerland and in the US, green roofs are becoming more popular. The UK is too learning the benefits of these roofs and are always being encouraged to use them. There is a green roof Centre in Sheffield and London is now too encouraging the promotion of green roofs in the city.
Advantages of a green roof
Long lasting - due to the vegetation on the rooftop, the roofing materials are protected from the elements which would normally damage it. Green roofs can last more than 50 years.
Energy saving - high insulation which means less heating bills.
- Reduced drainage requirements - the vegetation will ensure that water is retained which reduced run off and lowers the requirement for drainage systems.
Increases property value - they are more eco friendly and produces an extra recreational space, therefore more appealing to potential buyers.
Keeping traditional craft going - keeping history alive by using a roofing method thousands of years old!
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