VERNACULAR PICTURES 8: KOUSHI

Continuing on somewhat from last week’s post on the filtering functions of the building envelope, here I would like to consider the Japanese koushi: the timber lattice covering the (usually front) windows of Japanese townhouses.

View of the street through the koushi from within the entrance of a townhouse.

View of a koushi-covered facade at night.

The koushi is a great example of the ‘subspecies’ that arise within any element or ‘species’ of vernacular architecture, evolving over time via a process of functional and regional differentiation. The generic koushi has several basic functions: to provide security against forced entry, and to grant the inhabitants some privacy from prying eyes (although privacy was not really a concept in pre-modern Japan, nor one for which the Japanese language even had a word: today they use the English transliteration puraibashii). Aesthetically, koushi provide a sense of verticality to windows that are generally in a ‘landscape’ orientation, and adds rhythm and fractal detail to an otherwise fairly unornamented facade.

A fine koushi showing one of many patterns of cutting the ‘slats’ short at the top to admit more light without compromising on privacy.

Koushi consisting of alternating stout, full-length members with shourter, finer members.

Machiya townhouses containing valuable commodities like alcohol (sake) had the stoutest koushi, called sakaya ‘sake shop’ koushi. Likewise, rice shops (komeya) had komeya koushi, with thick, roughly dressed members that could withstand impacts from wayward barrels of rice and shrug off any scratches and dents. Charcoal shops (sumiya) had sumiya koushi, with very wide, closely-spaced slats, to prevent breezes and drafts from stirring up carbon dust inside the shop. Silk-weaving premises (itoya) and other industries involved in precision craftwork had thin, widely-spaced itoya koushi, to allow in as much light as possible.

Examples of some of the most common types of koushi. From left to right: itoya koushi, sumiya koushi, sakaya koushi, and komeya koushi.

Koushi have become something of a lazy cliche or trope in modern architecture, both in Japan and the West. A common modern abuse or misuse of koushi is to use them in front of blank walls, or to partially obscure things which would be better off completely hidden.  Traditional koushi draw the eye and entice the attention because they are always in front of something worth looking at, i.e. a garden (possibly welcome attention), or a front room (probably unwelcome).  Modern ‘decorative’ koushi on blank walls would have baffled carpenters of old. 

A modern Japanese example of koushi: frameless; consisting only vertical elements all identical in length, dimension, and setback; and arbitrarily covering both windows and blank wall.

Modern or modernist koushi are also almost always without a perimeter frame and lacking any of the subtlety imparted by varying the length, dimensions, or setback of the vertical members.  There are aesthetic (“It looks more sleek and modern!”) and no doubt economic motivations for this simplified form, and it can be effective, but rarely. 

BUILDING ENVELOPES AS FILTERS

The envelope of a building can be thought of as an assembly of filters, with each filter allowing, and preventing, a particular set of elements from passing through it. These elements might include heat, cold, light, radiation, water, moisture, rain, snow, air, drafts, breezes, fire, embers, smoke, views, sound, noise, strangers, children, burglars, pets, farm animals, insects, smells, dust, pathogens, toxins, vehicles, or projectiles. The strongest filter is a thick concrete bunker wall; the weakest is a large opening without door or glazing.

Many of the filters in buildings are operable or ‘tuneable’ to some extent, the most obvious examples being doors and windows. In most Australian houses, the conventional filter arrangement for windows is an openable, clear-glazed sash, with a flyscreen which may be fixed or openable/removeable. Flyscreens are considered essential to keep flies out in summer, and mosquitoes out at night - in other, malarial places, the ‘insect filter’ might be brought within the envelope, in the form of a mosquito net over the bed.

So the conventional filtering options for a window are: with sash closed, admitting light and view but excluding air, smells and most sound; with sash open, admitting light, view, air, sound and smells. Adding some combination of blackout curtain, lace curtain, and/or blinds gives you additional control over light and views.

There are other, less conventional ways of arranging the filtering functions of a window: you might have two-part windows, for example, with one part fixed glazing and the other part an insect-meshed opening fitted with an operable shutter. The advantage of this arrangement is that it avoids the expense and complexity of a modern operable glazed sash, and can be constructed DIY without too much skill or trouble.

Glass is something of an illusory material in that it gives the impression of openness, but in fact a closed window, while it admits light and view, filters out a great deal else, and largely excludes the exterior from the interior in the sensory sense. A house with an envelope consisting almost entirely of floor-to-ceiling fixed glazing is much less in contact with the outside environment than a house which is all solid wall other than for a single unglazed opening.  This isn’t necessarily a bad thing: in unpleasant environments, the ability of glass to divide light and view off from the other senses is often desirable, and one we take for granted.

In contrast, the semi-opaque paper-covered shoji of traditional Japanese dwellings admit light and sound but not view, and their solid timber amado shutters prevent sound to a degree, but exclude light. You cannot have light without sound, and you cannot have vision (view) without the other senses: smell and touch (breezes) and, in winter, cold. Again, the filter is brought within the building envelope, in this case in the form of warm clothes.

VERNACULAR PICTURES 7: EARLY AUSTRALIAN VERNACULAR

The early cottages and huts of Australia’s pioneers and settlers have great charm and appeal. Their primitive, at-hand materials - bark and log or corrugated iron roofs, timber slab walls sometimes rendered in clay or lime, and the characteristic ‘standoff’ chimneys, with flues also often constructed in timber and bark - soon gave way to more refined options once they became available, but the basic form - small, rectangular and compact, a central entrance and hall with a room on either side, steep gabled or hipped roofs - survived into the 20th century in both rural and urban contexts, as the workers cottages and miners cottages so popular in inner suburbs today.

VERNACULAR PICTURES 6: TENSILE STRUCTURES

Tensile structures are extremely rare in traditional architecture, because the most common traditional materials of that architecture - stone, brick, and mud - have almost no tensile strength. Timber is the exception, but even timber is relatively weak in tension, and has traditionally been used either under pure compression (posts and columns) or under bending (beams, lintels, joists, and rafters), where the tensile strength is a component of bending strength. Timber trusses, which contain members in pure tension, are a relatively recent invention, and rely on quality metal fixings at the nodes. Large-scale tensile structures didn’t become feasible in architecture until the appearance of quality steel, in the form of truss members and cables.

Traditional and even contemporary buildings are almost all compressive, and all extant ancient buildings are too, because only compressive structures endure. The pyramids of Egypt are the standout example, and owe their extreme longevity to the maximal stability of their form- a pyramid is really just an organised pile of rocks, tapering from base to apex, at or near the angle of repose.

In contrast to the inherent stability of compression structures, tensile structures are inherently unstable; or rather they have a dynamic stability, which is part of their aesthetic appeal. They are less suited to fixed buildings than they are to portable or ‘velocity’ structures where lightness is important- think sailboats, early aeroplanes, bows, and bicycles.

There is one traditional architectural tensile structure, however, that shares the same attributes as these non-architectural tensile structures: the tent. Indeed, tension and tent (and many other English words like tendon and tendril) come to us from the same root: the proto-Indo-European ten-, meaning ‘to stretch’. Tents make use of the few ‘contrary’ traditional building materials that excel in tension but have no compressive strength - fabric, hide, cord, and rope - in combination with economical use of compression elements such as poles.

Perhaps because of their ephemeral nature, tents get far less attention in the architectural world than the more solid and long-lasting building typologies constructed in stone or brick or even timber. Probably the best-known vernacular tent type is the ‘black tent’, whose traditional distribution stretches from North Africa to Central Asia; tents of this type are still in common use by the nomadic groups of these areas. The more famous Mongolian ger and Central Asian yurt are arguably not true tents, at least not in the structural sense, since the ‘skin’ is just a veneer hung over timber lattice walls and a timber rafter roof.

Black tents are perfectly suited to the hot, dry, windy desert climates in which they are found. Black may seem an ill-advised choice of colour, but it gives the fabric greater longevity against UV radiation, and also serves to create a vertical temperature differential in the tent, drawing air through it from the bottom to the ridge. The density of the fabric weave means that under normal conditions, air (but not sand) can pass through the fabric itself; on the rare occasion that it rains, the threads swell up to become more watertight. The walls of the tent can be opened or closed depending on the conditions, and the low-slung form allows the tent to stand against ferocious wind and sand storms.

The traditional method of repairing the fabric of the black tent is somewhat poetic and almost biological: when the strips of fabric closest to the ground are frayed beyond repair by wind and sand, they are removed, but not directly replaced; instead, the two sides of the tent are unstitched at the ridge, the two new strips are inserted there, and the two sides are stitched back together, so that each strip, newer than the strip below it, moves down one position in the wall, until it eventually reaches the bottom and is removed in its turn.