I would say that there are two different general concepts of 'Traditional Architecture': 1) the ethnological one and 2) the anthropological system.
1) the ethnological concept
The ethnological concept studies mainly domestic architecture as found in rural domains of modern states. A parallel term is 'Vernacular Architecture'.
Its main focus is on the domestic house, tent or hut. Depending on the cultural environment it is vaguely classified according to economico-anthropological categories, e.g. hunters and collectors, cattle-breeders or primary or advanced agriculturists.
In regard to its cultural significance 'traditional architecture' is usually understood as an important part of material culture, in its origins related to 'shelter'. It was developed, the 'theory' says, to protect humans against negative influences of climate, that is: heat, rain, winds, low temperature, snow etc.
The global diversity of traditional (or vernacular) architecture recorded recently can be found in the 3 volumes of the "Encyclopedia of Vernactular Architecture of the World", edited by Paul Oliver, published in 1997 by Cambridge University Press. The first volume shows a heterogeneous collection of theoretical approaches, which are however problematic because they project the value system of Eurocentric 'high culture' disciplines on an object which has much more temporal depth and originality as a highly complex tradition. Main problem: the disciplinary 'high culture' system rejects rural tradition because of its incapacity to produce evidence in regard to temporal depth. Thus, the discussion of 'traditional architecture' ends up in a kind of romanticism of rural 'arts and crafts'. Recently there was even a discussion somewhere (Oxford Brookes) about 'vernacular style'!
2) 'Traditional Architecture' in the anthropological framework
This uses a quite different approach saying that conventionally 'architecture' is an elitarian term related to the cultural superstratum called 'civilisation' characterized by durable monuments, script, centralised towns and cities of larger territorial agglomerations, like states and empires. Traditional 'building' is devalued due to its ephemeral character of materials (no sources in archaeology), lack of invention (stereotype reproduction, no history) no post-medieval Renaissance projection of god-like designer-creator (consequently banal!).
However, we can avoid this urban value system by redefining architecture in new ways, working with facts. The term architecture has to be redefined in a much larger and temporally deeper framework using terms like 'constructive behaviour' and its results as 'tectonic artefacts'. We gain a new field of research called 'architectural anthropology' or 'anthropology of habitat and architecture' (Egenter 1992) -> http://home.worldcom.ch/~negenter/005_ResSerOnline.html
This new definition of architecture shows us some quite new things. The 'shelter'-type, the 'hut', was not an early form of architecture. It had predecessors.
Most important was 'semantic architecture' with its 'toposemantic' functions. There are reasons to assume that in Paleolithic times it must have been important for food control and spatial organisation of temporary campsites.
Later, in neolithic times, 'semantic architecture' became extremely important for the continuous occupation of local territories and sedentary life. The system can be called 'settlement core complex'. It used semantic architecture in the form of 'nuclear borders' which, by cyclic renewal, archived the fibroconstructive foundation-marker of the village and the hegemonial rights of the founder-house, thus creating an elementary type of social hierarchy.
This type of spatial and temporal village organisation can still be studied in many places of the world where local traditions had been upheld by the local sedentary agricultural populaton (See Egenter 1982, 1994b)
It also developed symbolic functions similar like the Chinese YinYang. Without human intention 'semantic architecture' autonomously produced an aesthetico-philosophical model. Assuming that neolithic farmers for existential reasons had to deal intensely with this symbol in their environment led to a prototype of human culture.
It produced a model of 'categorical polarity' and thus became the prototype of art and aesthetics (PRO-portion). Basically this was used in early cognition by analogy of semantic architecture and natural forms (top + trunk = tree). Increasing in density, this became a basic philosophy of the harmony of all things (Greece: hen kai pan).
In other words: this neolithic spatial localism or 'toposemanticism' formed a cluster of autonomous and harmonious village-cultures in many regions which was structured by cyclically renewed fibroconstructive semantic architecture.
In some regions of the globe, struggles for domination began in these clusters. We call this the beginning of civilisation. The most ancient village had chances to become the state centre. Its founderhouse provided the palace, its representant the regional duke, the king, the pharaoh, etc..Very likely its semantic architecture - hewn into stone - became the central sanctuary of the new state.
This transition from polycentric localism to a monocentric state had tremendous implications for the human condition. Mainly, because, what we mentioned at the beginning, a definite social class system was established which set up new values to dominate the others. Thus, the values of local traditions became devalued. However, some of them were preserved, even using them for power: semantic architecture hewn in stone!
With the spatial extension from village localism to state territory, many villages lost their autonomy. Their aesthetic values lost their meaning, because the fibroconstructive materials and cyclic tradition were devalued. Art and architectue became monumental, that is, formed in durable materials for eternal continuity! Polarity was vertically extended into planetary and macrocosmic dimensions. Aesthetics became an 'ideology'. The absolutely spiritual was projected into planetary heigts (Akhenaton syndrome). Early states became theocracies governed by a king who represented the theocratic line.
Foundation rites were interpreted as creation, a system which was gradually enlarged to macrocosmic dimensions. Philosophically too polarity was dissected into a spirtual world and an empirical or materialistic world. Science dissolved the system of polar harmony. It began to isolate things spiritually and empirically.
'Harmony of heaven and earth? Or, a world that has become too large, a world that ran out of control?
Thus, 'traditional architecture' can tell us in new ways how architecture evolved, how it developed fibroconstructive semantic, domestic and sedentary forms and, at the same time, how aesthetics and art evolved from semantic architecture, and how this was preserved through enormous times by those local traditional inhabitants of neolithic villages by cyclically renewing the ephemeral material of the primary artful forms.
Suddenly we become aware that we owe a lot to the content of the term 'traditional architecture'. It means much more than 'local architectural dialect' as the term 'vernacular architecture' implies.
Human beings seem to have conserved elements of this anthropological depth of 'traditional architecture' showing some sort of archetypes in their heads. Maybe tourism is an indicator: many peoples living in cities prefer traditional rural environments for their recreation periods.
Premodern architecture preserved many of these 'archtype-forms: Doors, gates etc. as signs indicating transition from space to place, from public to private. Roofs as catgorically polar symbols indicating the local world of a family. Windows as 'buildings in the building' allowing visual 'transcendence' of the microcosmic inside into the macrocosmic outside! Evidently, there is some profound need for this ancient aestheticism of categorical polarity.
And, finally, the toposemantic element! The house as a sign of my own life in the natural environment! What a difference compared to urban mass housing!
But, neither the art historian, nor the modern architect know about these things. The art historian is a 'civilised' historian, trying to rationally interprete art which in fact is irrational, and the architect has adapted to technology and functionalism which he quite naively declares as aesthetic. A boring aestheticism without any temporal depth!
Aesthetics, as we tried to show, have temporally deep cultural roots. The ever changing architectural styles in recent decades show clearly that neither art historians nor architects know about the deep-rooted meanings of aesthetics.
If we assume that the subjective search for art today has something to do with this transition from a 'toposemantic' local world to a larger imperial, continental, global and macrocosmic world, with its extended spatial concepts of order, then we might try to do more research into this anthropological domain of 'traditional architecture'.
Sacred Symbols of Reed and Bamboo; Annually built cult- torches as spatial signs and symbols. Swiss Asiatic Studies Monographs vol. 4, Zürich
Architectural Anthropology - Research Series, vol. 1 >The Present Relevance of the Primitive in Architecture< (edition in 3 languages: English - French - German). Editions Structura Mundi, Lausanne
Architectural Anthropology. Semantic and Symbolic Architecture. An architectural ethnological survey into hundred villages of central Japan. Structura Mundi, Lausanne
Semantic Architecture and the interpretation of prehistoric rock art: An ethno-(pre-)historical approach. In: Semiotica 100-2/4:201-266
The Deep Structure of Architecture: Constructivity and Human Evolution. In Amerlinck, Mari-Jose: Architectural Anthropology. Bergin & Garvey Westport CT London
Vernacular architecture - where do the symbolic meanings come from? In: Architecture, Research, Ljubljana
ca. 70 papers: http://home.worldcom.ch/negenter/005_ResSerOnline.html
Title page: http://home.worldcom.ch/negenter/
Architectural Anthropology (vol. 1) figures among ca. 200 books under the title
*Theory of the world*