Iron-age Viking longhouses were burned and buried in funerals
(PHYSorg.com Archaeology & Fossils)

From the Bronze Age until the Viking Age, burial mounds could be placed on top of the remains of three-aisled longhouses. The internal posts that served as roof-supporting beams were sometimes removed before the house was set on fire. Once the house had burned to the ground, one or more burial mounds were placed on top of its remains.