Datça vernacular houses as a rule-governed plan language: a shape grammar and J-graph reading

Vernacular housing studies have documented spatial patterns in detail, yet the rules that generate these patterns are less often formalised within a single analytical framework. This article examines how traditional Datça houses can be read as a rule-governed plan language, drawing on 13 analytically selected cases from a documented Reşadiye housing corpus. Shape grammar is used to extract formation, articulation and growth rules from the corpus; dual-root J-graph readings, supported by basic J-graph-derived topological indicators, are used to test topological consistency. The analysis reveals a core – growth – derivation logic: [GARDEN] and [ROOM 1] establish the corpus-wide core, while [ROOM 1] also drives primary growth. [ROOM 2] appears as a subtype-specific derivative unit; [KITCHEN] and [STORAGE] form a recurrent non-core service layer; and [HALL] acts as a conditional distributive node in more complex or vertical cases. Controlled derivation serves as a methodological proof-step, testing whether the extracted rules produce consistent intra-grammatical variation. The model shows that a local vernacular corpus can support rule extraction and topological verification within the same analytical framework, extending the analysis from descriptive documentation to plan-language formation.