Vikings dwelt in single-family longhouses. A single family would usually include many children, servants and perhaps grandparents. The longhouses consisted of one long room with a fire pit in the middle; there might have been a wooden partition to screen off the bed of the master and his wife. If the household was wealthy, the house might have had a bed with wooden sides and a locking door. Windows were rare and the doorway would be so low you had to stoop to enter. This made the house easier to defend.
Mark off the area of the house. It can be no wider than one and a half times the length of the roof poles.
Make the frame of the house by digging a 3-foot-deep hole every 4 feet along the wall of the house and standing a log in it. Pack the soil tightly around the logs. Cut notches in another set of logs so that they will sit securely on top of these logs. These logs will be the top of the walls and will support the roof. Nail these logs in place.
Nail log rafters in place across the tops of the walls over every vertical log. This will keep the building square. Nail a low threshold over the doorway in the centre of one of the short ends..
Cut four logs to the length of your roof poles. Notch two of them 6 inches from one end so they will fit together at a 135-degree angle. Notch the outer end of the angle so that it will fit over the top of the outer wall at the front end of the building. Put these logs up to form the front gable of the building. Nail them in place. Form the back gable in the same way.
Nail together poles to form the ridgepole of the roof. The ridgepole should be 2 feet longer than the house. Center the ridgepole in the angle formed by the logs at the top of the gables. Nail it in place.
Place long sticks every 6 inches between the vertical logs. Weave flexible branches over and under these sticks. When you reach the end of a stick add another one. Fill all the walls, including the space over the door and the gables. Plaster the woven sticks with mud on both the inside and the outside. The mud will dry to make a sort of plaster. This is called "wattle and daub" construction.
Nail the long poles from the ridgepole to the sides of the roof. Make panels of woven sticks to cover the poles. Cover the roof with sod. Leave a smoke hole in the centre of the roof.