Not all thatched roofs are made from the same plant. There are various different materials, each with their own properties, strengths and weaknesses. In England, there are three main types of thatch. The choice of material for each particular project must take into account the tradition of the area, especially in the case of listed buildings, as well as the intended final aesthetic finish of the roof.
Combed Wheat Straw
In much of the West Country this is the predominant traditional roof covering. Modern varieties of wheat have been bred to be short in the stem to optimise grain production and are unsuitable for thatching as a result, especially when they’ve been collected with a combine harvester. Older strains of wheat are therefore specifically grown for thatching and are harvested and handled in a more traditional process. Combed wheat straw is an incredibly versatile thatching material, able to ‘turn’ corners and negotiate features of a complex roof, pliable, flexible and strong.
Water Reed
For hundreds of years ‘Phragmites Australis’ has been used as a construction material in places which were close to natural reed beds such as in Norfolk. In recent decades, water reed has spread outside these areas due to it’s reputation for longevity and the advent of a reasonably priced supply of imported material. In contrast to wheat straw, this is a hard, woody plant. In the right conditions, water reed can last many decades on the roof, but often creates a more harsh, angular aesthetic which perhaps is more suited to modern buildings.
Long Straw
This begins life as the same material as combed wheat straw, but is prepared for thatching in a very different way. The straws are ‘drawn’ in handfuls from a ‘bed’ of wetted straw, essentially a heap of randomly arranged wheat straw. The purpose of this is to orientate the individual straws in roughly the same direction. They can then be tied into bundles, known as ‘yealms’ which are applied directly to the roof. The resulting effect is slightly less refined than either combed wheat or water reed, but can create a pleasingly ‘shaggy’ finished product.
For most historic thatched buildings in Dorset we strongly advocate combed wheat straw as the traditional material of choice.