Thatched roofs were the main form of roof construction for many hundreds of years throughout many parts of mainland Europe and were particularly popular in the United Kingdom. Early forms of thatched roofs in the UK can be traced back to Celtic Roundhouses (circa 750BC to 12BC) where a combination of straw and mud were used in order to try to provide a watertight environment. The Romans (circa 43AD to 410AD), Anglo Saxons (circa 420AD to 650AD) and the Vikings (circa 700AD to 1000AD) all continued to make use of natural resources such as timber for buildings and straw and reeds for thatch for their roofs. However the Medieval Age (circa 1066AD to 1500AD) is arguably the period of UK history where the use of thatch really accelerated and there are many examples of these types of building still in existence today. Many Tudor Buildings (circa 1485AD to 1603AD), continued to make use of timber frames with thatched roof however toward the end of this period other types of materials such as clay tiles were starting to be introduced in place of thatch.
It is easy to wonder how thatch is able to provide a watertight roof surface given that it is fundamentally straw or reeds placed on top of a building that is exposed to the elements often over a long period of time. The answer lies in the manner in which the thatch is installed and the pitch (angle) to which the roof is constructed. In fact if you compare a thatched roof to a roof constructed with concrete or clay tiles you will often find that the thatched roof will have a much steeper pitch, typically 50 to 55 degrees, which allows rainwater to be shed much more readily.
The Conservation of Traditional Thatch Group (Online) provide a useful insight of the thatching process:
‘Most underlying roof structures are formed of timber with the thatch supported by battens spanning between rafters. The main coat of a thatched roof is formed by fixing bundles of thatch, with their lower ends aligned, in overlapping courses from the eaves and verges upward towards the ridge, to form a thick layer (or coat). For most roofs this will be about 250-300mm (10 – 12 inches) thick, although in some techniques much thinner coats are used. For a new thatched roof, the thatch is fixed by tying to the rafters, battens or other support. Subsequent coats can be applied over the remains of underlying coats and fixed using spars and sways or metal fixings.
Thatch was traditionally fixed down by clamping the bundles to roof timbers. Sways (long hazel or willow rods, about 2-3cm (1 inch) in diameter) were laid across the bundles of thatch and held in place with twine or rope passed down through the thatch by means of a hook or large ‘needle’ and tied round the support. In the earliest roofs, plant stems were used, but by the 18th century hemp rope or twine (sometimes tarred to discourage damage by rodents) became the norm. Wire netting was introduced in the late 19th century to provide additional protection from birds and rodents. Nowadays, plastic netting is often used. Netting can be applied to either just the ridge or over the entire roof’
As you would imagine from reading above, thatching a roof requires a skilled craftsman who has undertaken their ‘apprenticeship’ over many years, and this is not something that should be attempted by anybody. We must ensure that we protect this craft to ensure that traditional thatching skills are not lost and in the process help to ensure that we can continue to enjoy the many wonderful thatched roof buildings that we have throughout the UK.
Take a look at the series of youtube videos below which show the thatching process in excellent detail:
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