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Thatching with Green Broom in Spain
Similar in use to the more usual UK Heather (Ling) as in the 'black houses' of county Durham and bothey's in Scotland
Prof. Carmen Menéndez High School of Architecture, Madrid Polytechnic University
Escuela Técnica Superior de Arquitectura - Madrid
Thatching is probably a construction concept that doesn't come easily to the mind of a north European in connection with Spain. Yet, the silhouette of a steep thatched roof echoed in a landscape of abrupt mountains and deep valleys softly coated by thick ancestral forests, is a prototype in a large area of cattle rising economy in Asturias (1). This is the Atlantic land that witnessed the turning point in Medieval Spain, with the defeat of the Arab armies forced back to the South from the high strongholds where Visigoth power had retreated.
Perhaps that historical fact can be linked in a metaphor of meanings. The northerner thinking of a Spanish roof will most probably picture a red one, covered with what is called in English Spanish tiles, or, in the American variety of the English language, Mission tiles, because such was the roofing material used in churches and chapels by the Spanish missionaries along the Californian coast. But the linguistic association is different in Spain, where this single curved tile is called teja árabe, that is, Arab tile.
Beech and chestnut groves, birches, holly trees, oaks, hazels, with a profuse underwood of thickets and bushes with varieties of heather and broom, are the usual sight for a hiker in the interior counties in S.W. Asturias, where protected animals like the brown bear and the capercaillie can be found wild still. Farmland and pastures for the cattle, wedged down at the bottom of the valleys, are walled by the forest-clad slopes. Other pastures are just slanted patches of green cleared with difficulty by man in the wilderness. In those grazing spots, and also in some hamlets perched on the slope of the valleys, roofs thatched with green broom appear here and there, keeping with a tradition that goes back to the earliest human settlement in the area.
If it is true that today most of the old dwellings have had their thatch replaced by the traditional teja árabe (and certainly tiles and slates are the choice in all new ones), in Somiedo--the large county in the south-west--green broom is the material kept predominantly in agricultural constructions, such as cowhouses, and is kept in two ancillary buildings: a traditional granary on staddles and an old watermill.
So, the hiker willing to walk for distances and climb slopes of different grades can reach clusters of thatched constructions (some count as many as thirty or more) in shielings where the high pastures are grazed in summertime by transhumant cattle.
Shieling cowhouse - ridgepoles held by forks
Thatched constructions share the same building technique and use locally available materials, such as lime stone for the masonry walls, beech and hazel wood for pole timbers and wattling, and green broom for the thatching of the roof. Different solutions and finishes to hold the broom fixed at the crowning ridge are displayed in the different valleys.
Byre-Houses and Cowhouses
Those thatched houses that remain are of the traditional type byre-house (under one roof), also found in other northern regions, like the Dutch Los Hoes and the Hebridean Black House. In this Asturian type, the living quarters and byre might be separated by a masonry wall. Wattling (which I consider a tradition culturally linked to thatching) is found in older stalls, with crafty wattle hurdles for the cribs. Although people live today in new tiled homes, the old thatched houses (now listed) have been converted into byres with the extra space used for storage.
Cowhouses in the shielings are often built into the hillside, two-storey rectangular building allowing for the stalling of cattle below and with the upper storey beneath the roof as a loft for hay storage. A hipped-roof structure, highly pitched, is erected over stone masonry walls with two low gables. Pairs of diametrically opposed rafters span the length of the shelter, (of an average size for twenty cows). These rafters bear their tenoned-ends on the wall- plates, and cross at the top by means of a tongue-and-groove joint. No ridge pole is usually needed, and stability is ensured by three tie beams. Purlins and braces that stiffen the rafters are set fixed by green broom twines (which the thatcher has twisted himself with his hands). Furthermore, the thrust of the roof is counterbalanced by jack rafters rising from atop the low gables to
Setting the Ridge Timbers - the Author lends a hand
join the first pair of rafters, where an upright with a natural fork might be used as well, as a load-bearing post.
Thatching by the Moon
Every year one side of these constructions is rethatched for maintenance of the whole structure. Cutting the green broom takes place earlier, and thatchers are very careful to keep the waning phase of the moon for this operation, as they do with any wood felling (2). Otherwise the broom does not last, they say.
Of the several bushes growing locally, the variety cytisus scoparius is preferred, a plant of deep green needle leaves which blooms with yellow flowers. Apart from being a more resistant variety, thatchers explain that the tiny grooves along its leaves help channelling off the rain.
Setting the Ridge Timbers - the Author lends a hand
When everything is ready, and the forecast is for a dry spell in this rainy country, bundles of green broom are piled by the side of the house and the thatcher (maybe with one helper to hand over the bundles) starts his work. He uses a pair of different sized ladders, which he needs to reach higher in the roof. Thatching is done in bands upwards, driving the green branches, one by one, into the old bed of thorny dull broom, their leaves turned downwards. Because old branches are hard and prickly, the thatcher uses one protecting glove, his only tool, that he wears in his thatching hand. When a roof is constructed for the first time, the thatcher proceeds in round circles starting at the bottom and rising till he reaches the ridge.
Topping the Ridge
The ridge is thatched with pairs of bundles of green broom laid with their leaves to the slope to form a thick ridge top. Two or more timber poles (beech branches) chosen curved at one end, are laid over the ridge bundles, the curved end securing the top of the hip.
There are two ways, broadly employed, to secure those branches over the top. One method uses hazel twigs with a natural fork, similar to spars. The sharpened end is fixed deep down through the broom, while the fork anchors the pole over the ridge. Stones (roofing slabs) are also used to anchor the ridge in some of the higher locations exposed to rougher weather conditions. Roofs thatched by this method sport a characteristic thorny profile. The other system uses three or four transverse timbers (called yokes) over the beech poles. Pegged to these yokes are hung pairs of long timbers, which saddle the slope of the roof each side.
Defenders of the first type argue that the broom tends to rotten under the long timbers, which prevent ventilation in the thatching. The first building technique is preferably chosen in shielings located at a higher altitude, but it is obviously also a question of local idiosyncrasy in the communities of the different valleys.
Finally, a few rare constructions have the ridge covered by inverted turves, which in some round-plan shelters are secured with a slab stone. These are mostly shelters used for calves in very high pastures, but where the herdsman might also take refuge occasionally.
Why thatch with green broom? The reason for the tradition of thatching with green broom in these areas instead of rye, used through centuries in nearby country, is obvious in settlements with a sole economy based on cattle rising and where no cereal crop, or very little, was ever harvested. The wisdom of this tradition is that thatching, with green broom locally available at no cost, is lighter than any other roofing material, and sets perfectly over a simple structure. It also provides airy conditions for byre and hay stock. From an ecological viewpoint the broom, endemic in some areas, is turned from a threatening invader of cleared pastures into a fitting roof material.
The wisdom of the local administration today, ruled by the new political autonomous system, is to have those constructions of traditional architecture listed (no corrugated iron is allowed any more), while providing small maintenance grants that encourage cattle herdsmen, each year, to keep thatched buildings in good shape. Besides, no other roof merges better with that mountainous landscape while preserving the beauty of the Asturian rural heritage.
1. Asturias with part of the Camino de Santiago (the Medieval pilgrimage to Saint James) running through it, is a montanious country of deep valleys, stretching out between the Atlantic Ocean to the north and the powerful range that sets the line with the Castilian plateau - and dry Spain- to the south. It borders east and west with the Basque Country and Galicia.
2. I owe to Robert West the information that Choctaw Red Indians in Mississippi were equally observant of the moon phase for the collection of the palm trees and pole timbers that they used in their constructions.
A Selection of superb line drawings recently sent by Prof. Carmen Menéndez High School of Architecture, Madrid Polytechnic University
© Carmen Menendez <firstname.lastname@example.org>
Grateful thanks to Prof. Carmen Menéndez for allowing this fascinating article to be published here