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The ins and outs of thatch
Thatch as a building material is an age-old practise and yet, even with the advent of newer technologies and materials, it is still relatively popular. We take a look at the pros and cons of using thatch, its history and why it ' s so popular, and innovations made in this area over the years.
By Kelly-Ann Prinsloo
Good quality straw thatch can last for more than 50 years when applied by a skilled thatcher. Image: Pixabay
WHAT IS THATCH?
Although thatch is popular in Germany, the Netherlands, Denmark, parts of France, Sicily, Belgium and Ireland, there are more thatched roofs in the United Kingdom than in any other European country.
Good quality straw thatch can last for more than 50 years when applied by a skilled thatcher. Traditionally, a new layer of straw was simply applied over the weathered surface, and this spar coating tradition has created accumulations of thatch over 2.1m thick on very old buildings. The straw is bundled into yelms before it is taken up to the roof and then is attached using staples, known as spars, made from twisted hazel sticks.
More than 250 roofs in southern England have base coats of thatch that were applied over 500 years ago, providing direct evidence of the types of materials that were used for thatching in the medieval period. Many of these roofs are thatched with wheat, rye or a maslin mixture of both. Medieval wheat grew to almost 1.8m tall in very poor soils and produced durable straw for the roof and grain for baking bread.
Technological change in the farming industry significantly affected the popularity of thatching. The availability of good quality thatching straw declined in England after the introduction of the combine harvester in the late 1930s and 1940s, and the release of shortstemmed wheat varieties. Increasing use of nitrogen fertiliser in the 1960 to 1970s also weakened straw and reduced its longevity. Since the 1980s, however, there has been a big increase in straw quality as specialist growers have returned to growing older, tall-stemmed,‘ heritage’ varieties of wheat such as Squareheads Master( 1880), N59( 1959), Rampton Rivet( 1937), Victor( 1910) and April Bearded( early 1800s) in low input or organic conditions.
Weathered reed is usually stripped and replaced by a new layer. It takes four to five acres of well-managed reed bed to produce enough reed to thatch an average house, and large reed beds have been uncommon in most of England since the Anglo-Saxon period. Over 80 % of the water reed used in the UK is now imported from Turkey, Eastern Europe, China and South Africa. Though water reed might last for 50 years or more on a steep roof in a dry climate, modern imported water reed on an average roof in England does not last any longer than good quality wheat straw. The lifespan of a thatched roof also depends on the skill of the thatcher, but other factors must be considered – such as climate, quality of materials and the roof pitch.
In areas where palms are abundant, palm leaves are used to thatch walls and roofs. Many species of palm trees are called‘ thatch palm’, or have‘ thatch’ as part of their common names. In the south-eastern United States, Native and pioneer houses were often constructed of palmettoleaf thatch. The chickees of the Seminole and Miccosukee are still thatched with palmetto leaves.
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