Remains of roofs are rarely preserved so we know little about them. They may have been thatched but at that time people did not grow corn with long stalks as rye later in Middle Ages and modern times and the people also cut the corn below the ear rather than cut the whole stalks. They could have been made from reed but we do not know if there was enough of it. There is the possibility (for prehistory generally) that they used, for example, strips of bark, it was experimentally tested. From the lake settlements of late Bronze Age shingles are documented.