TIMBER FRAMING
Timber framed construction enables several executions of panelling. It is only a construction, filling the spaces between the beams is another problem.
The main problem of the frame system is its construction in cross direction: theoretical rectangles can be pulled downwards with side stresses (wind, physical influences, bad, unsealed details). Vertical and horizontal elements of a frame need transverse connections as brackets. The bracket can be just a short lath at the corner or a system of crossed beams or a long beam over the whole construction, or as latticework.
The development of church timbers is instructive, starting with simplicity in basilical roofs with gentle slopes, more complicated timbers in gothic architecture and three-dimensional timber constructions in baroque. The timber in a basilica is a simple triangle of rafters and tie-beams, supported by intermediate posts. Gothic constructions have longer spans and steep slopes, the timber is often double, with a lot of supporting elements and it bears the ceiling – in the beginning flat coffered ceiling, later also curved surfaces. Baroque roofs cover complicated ground plans with a lot of circular or semi-circular shapes and have to be composed as three-dimensional constructions with a lot of brackets.
Kozolec / Hayrack is the most interesting example of wood construction found in Slovenia. This wooden object is a free standing, stable, permanent, mainly wooden, vertical, open but roofed object for drying and storing on laths. Yesterday it was grain. Today hay is mostly stored. A kozolec/hayrack has flat fronts of horizontal and vertical beams, connected by a transverse latticework. This means the front is firm, stable. The spatial construction is thus composed of at least two fronts, connected in depth with a stable plane construction (Juvanec 2oo7).
The construction of a kozolec/hayrack consists of at least two gables, connected by a longitudinal grid of wooden beams. The gable is constructed of two posts and two tie-beams – the upper one bears the timber. The lower part has the same width and height – it is a square. The timber is the same geometrical form, but rotated by 45 degrees. The lower tie-beam is equal to one unit, the upper one is the square root of two or half of a square.
The longitudinal unit is a composition of two horizontal beams, connected with posts and diagonals as bracing (latticework). The length of one field is normally 'one', but it can be multiplied, up to eight units, and the object can be almost 24 metres long.
A kozolec/hayrack has existed in the Slovene ethnic area or at least five hundred years, even on poorly stable terrain, on marshland. It can be understood as a connected, interwoven construction in all three dimensions. Using a square and its diagonals follows the theoretical principle of order: only three dimensions exist. It can be composed with only one dimension: width, other dimensions can be determined by a right angle and the square root of two (Juvanec 2007). This is not a limitation in designing the object, but simplification and avoiding mistakes in hewing the wood.
John May cited: 'Juvanec wrote about the kozolec/hayrack: this is the only ethnic architecture' (May 2012).
Frame construction with board coverings is the best protection for its contents. The walls can let in air and view only with drying sheds. Stables or even dwellings have to be closed, sealed. Frame constructions can be covered on inner or outer sides with boards or planks. An outer panelling covers the construction, the entire construction is visible if the panelling is on the inner side.
An inner position of panelling shows the frame.
This exposure is bad for the wood, but effective for interior climatic conditions. The dimensions of the logs in the frames of vernacular architecture are around 15 x 15 cm (12.5 x 12.5 in old systems with feet), with deep shadows – especially at noon, when the sun is shining most warmly (Juvanec 2012). Shade and the damp surface beneath it is a perfect cooling system, especially in a hot climate.
Boards cover the constructions and are good protection for the construction beams, which are more valuable than the boards themselves. It is cheaper to replace the boards than the construction beams.
Both cases can be found in vernacular, traditional architecture in countries rich in timber. All the natural conditions (sun, warmth, coldness, availability of materials, skilled masters) are used for sustainable architecture, successful not only for man as builder and user, but equally for natural resources.
Half-timber is a frame construction, filled with wattle, wattle and daub, adobe or fired bricks, rarely in stone. This filling can be rough or covered with plaster and whitewashed with lime. The last shows its construction and filling and can be extremely decorative. This system can be found mostly in northern France, Germany and Great Britain.
Wood is a perfect natural material: it is available, easy to treat and warm to the touch, it is an almost human material, close to its user. Its quality depends on the choice of species, of growth in nature (elevation, density of growing, weather conditions), but it has to be cut at the proper time (in winter: when the trunk is 'sleeping', with less liquid, and transport is not dangerous, Juvanec 2012), with proper drying (oak needs seven years for drying, changing its position at least four time a year), and the biggest problem is warping.
Wood is very popular in all architecture because of these properties.