Geometric lattice joinery

Gereh-chini assembles small wooden pieces without glue or nails into geometric lattices for doors, windows and orosi sashes, often with coloured glass.

Patterns derive from girih star-and-polygon systems shared with tile and stucco; masters work from compass-drawn layouts.

Joints loosen with humidity changes; avoid forcing sashes and keep wood dry.

Lattice-joinery in the Iranian architectural sphere is widely considered an outgrowth of earlier Islamic architectural timber framing, reaching sophisticated expression from the Timurid into the Safavid and Qajar eras. While surviving early structural woodwork is scarce due to fire and climate, historical accounts suggest that intricately pieced screens developed as practical climate modifiers across the Iranian plateau. In sun-drenched central oasis cities such as Isfahan, Kashan, and Yazd, as well as western centers like Sanandaj and Tabriz, wooden lattice screens served to diffuse harsh desert sunlight, reduce solar heat gain, and maintain privacy without obstructing ventilation. The integration of mouth-blown tinted glass into vertical sash windows, known as orosi, is often associated with the late eighteenth and nineteenth centuries, reflecting changing domestic aesthetics. Regional variations emerged primarily through available timber species, ranging from plane and walnut in mountain zones to cypress or poplar elsewhere, reflecting local builders' responses to thermal expansion, seasonal humidity, and interior lighting needs.

When examining historic or traditional lattice-joinery, observers should first inspect the joinery methodology at intersections. True traditional gereh-chini relies entirely on friction-fitted tongue-and-groove or notched wooden members without modern metal staples, synthetic glues, or concealed pins. Connoisseurs examine whether individual wooden struts display slight structural irregularities, gentle plane marks, and soft edges typical of hand-chiseled craft, contrasting with the strictly uniform, burnt, or perfectly perpendicular cuts of laser or automated saws. In glazed sashes, inspecting the glass pane edges where they meet wooden grooves helps determine age; early mouth-blown cylinder glass reveals thickness variations, wavy undulations, and trapped seed bubbles, whereas modern float glass is completely flat. Structural conservation requires careful humidity regulation, as abrupt desiccation causes shrinkage and joint separation, while excess dampness prompts swelling and buckling. Rather than applying surface varnishes that seal the wood pores, custodians traditionally rely on minimal dry brush cleaning and passive climate stabilization to preserve structural flexibility.