Joya de Cerén

Joya de Cerén is a small pre-Hispanic Maya farming village in El Salvador that was buried by an eruption of the Loma Caldera vent around 600 CE. Because the village was covered quickly by fine, moist volcanic ash, it preserved everyday buildings, their contents and the remains of their roofs in a way that is very rare in the humid tropics. It was inscribed on the UNESCO World Heritage List in 1993.

The site was found by accident in 1976, when a bulldozer driver levelling ground for a government agricultural project uncovered buried structures. Archaeological survey has identified 18 structures, of which 10 have been fully or partly excavated, according to UNESCO.

Buildings

All the buildings are made of earth. UNESCO notes that public buildings and the sweat bath used rammed earth, while household buildings used wattle and daub (bajareque), a technique of poles and woven sticks plastered with clay that copes well with earthquakes. Crack patterns in the walls suggest a small earthquake struck shortly before the eruption.

Excavated buildings include a large communal building beside a plaza, two dwellings, three storehouses, a kitchen, a sweat bath and two religious buildings. Each household used several separate small structures rather than a single house.

Roofs

The roofs were thick thatch carried on a timber frame. In their 1990 report on household archaeology at Cerén, Payson Sheets and colleagues describe wall poles that rose above the clay to support the roof, vertical posts tied into the ceiling system, and in places a raised pole platform (tabanco) spanning between walls. Adobe columns sometimes served as bases for roof posts. The roofs of some structures projected well beyond the walls, giving deep eaves that kept rain off the earthen walls, and pottery was found in fallen roofing material under the eaves.

When the ash fell, the thatch collapsed onto the floors but remained identifiable, and the excavators collected large amounts of roofing material for radiocarbon dating. Residents also tucked obsidian blades into the thatch for storage, and some were recovered there with organic residues still on them.

Why it matters for roofing history

Thatched roofs rarely survive more than a few decades, so most knowledge of ancient Mesoamerican house roofs comes from post holes, depictions in stone or modern ethnography. Cerén provides direct physical evidence of how ordinary Classic-period roofs were framed, how far eaves projected, and how roof space was used for storage. Its combination of earthen walls, separate small buildings and steep thatch is similar to rural houses still built in parts of Central America.