A very quick DWF impression of the structure for a small Anglo Saxon house can be found here. (As with any other DWF you will need the Autodesk Design Review software.) This model is based on a reconstruction at the Bentley Wildfowl and Motor Museum.

You can see the house is set into the ground lined with wood and the roof is made of fairly carefully placed straight branches woven together. The 'roof' would often then be covered with wooden tiles or bark or something that was similarly easy to find. The roof tiles are not shown in this diagram.

Some of the richer people in Anglo Saxon times might have had proper walls to their houses, but even fairly large houses would seem uncomfortable to us.