The intensity of a conflagration that consumed an early Iron Age public building at Tel-Hadar, on the eastern shore of the Sea of Galilee, Israel, was determined by thermal simulation. A thick slag layer was found in some ground floor rooms of the building. Fragments of burnt brick were found in the slag layer while unfired mud bricks were found outside these rooms. - The maximum firing temperature of the conflagration is estimated from the mineral assemblage in the slag. The slag was formed by partial melting of the mud bricks at about 1200°C. The burnt brick was heated to 1100 °C. - The duration of the conflagration is estimated from the relative amount of cristobalite in flint pebbles that were found in the slag and burnt brick. The cristobalite was formed by the heating and its amount indicates that the maximum temperature reached, 1200°C, was maintained for a short time (less than one hour), indicating a short intense conflagration. - The intensity and the high temperature of the conflagration indicates that the rooms contained large amounts of combustible material. Carbonized grain found in the ash may indicate that a storeroom full of grain was burnt.