The thatched roofs of Japanese minka farmhouses are an indispensable part of their overall character. These monumental, steeply pitched roofs might be oppressive or overwhelming if clad in any other material, but the inherent softness of thatch and its fine-grained, almost porous texture gives these buildings a distinct warmth and an impression of welcome and shelter.
Thatch is probably the most sculptural of all roofing materials: its smooth, rounded hips and valleys, uninterrupted by capping or flashing; the creative and even fanciful solutions it allows in resolving complex intersections; and its great thickness, fully expressed at the eaves, are all difficult or impossible to recreate in any other material.
A cold-region minka with not only thatched roofs, but thatched walls: thatch is an excellent insulator.
Thatched roof with a beautifully smooth valley transition. Note also the grasses and even trees growing from the ridge capping.
A fine example of the subtle sculptural possibilities of thatch.
Due to fire concerns, thatched roofs have been absent from Japanese cities for hundreds of years, long replaced by tile. Unfortunately, thatch has also become a rarer and rarer sight in the Japanese countryside, due in large part to the fact that for most people, thatching only makes sense economically if it is undertaken as a communal effort, with each villager volunteering their labour in the harvesting of reeds and laying of the thatch, under the direction of a skilled thatcher, and each receiving help in their turn when it comes time to rethatch their own roof. The communities and community structures required for this reciprocal system to work barely exist any more, and to pay a professional crew to rethatch a roof is prohibitively expensive.
Incidentally, a thatched roof isn’t strictly waterproof. It relies on its thickness and the careful orientation of the ‘fibres’ or individual reeds within the body; they are laid at an angle slightly shallower than the pitch of the roof as a whole, just as tiles are. In extremely idealised terms, a drop of rain hits the topmost layer of reeds, travels along it for a distance, falls through onto the later below, travels along that, falls again, and so on; the thatch layer must be thick enough so that by the time the drop of water penetrates through to the underside, it is outside the wall of the building and exits the thatch at the eave.
Simplified and idealised diagram of how rainwater ‘travels’ through a thatched roof and exits at the eave.
Thatching has never been a part of the Australian vernacular landscape. The industrial revolution was already well underway in Britain by the time European settlement of this country began, and from the very earliest days roofs in Australian towns tended to be of corrugated iron or slate, both brought out from Britain as ships’ ballast. Outside of the more populated areas, settlers’ bush huts tended to use bark or boards as a roofing material, sourced from trees felled on site. At any rate, the dry climate means that the marshy areas needed to support the growth of reeds are relatively rare; add to that the ever-present risk of fire, and thatch was never going to be a viable proposition here, unlike in Britain. But steel roofing, probably the most common roofing material in Australia, in corrugated and other profiles, presents its own sculptural possibilities; these have barely yet been explored.