Sometime toward the end of the 18th Century, the people of Haida Gwaii developed a second type of house construction which more effectively married the post and beam structure to the exterior walls and roof. This six-beam house integrates all of the structural members and distributes the loads by employing more elaborate joinery, including mortis and tenon joints and interlocking features. The sheathing is further integrated into the post and beam frame by joinery. The extensive use of joinery in this type of house, with structural supports integrated into the exterior walls, adds structural strength as well as providing for column-free interior space. Because the six-beam house was built most commonly in the southerly Haida Gwaii settlements, the Anthony Island region has been identified as its birthplace. Perhaps this anomalous architectural contribution was stimulated by trading with European seamen, when new wealth enhanced artistic inventiveness among the Haida and they had obtained both metal tools and exposure to European and maritime joinery.
The unique six-beam house found only on Haida Gwaii intrigued the early photographer George Dawson when he visited there in the late 1800s. In these buildings, he observed, the roofs were not supported on central posts as in the more widespread two-beam construction system. They rested on the angled gable plates, the slotted corner posts, and six stout beams flattened on the lower side, which protruded beyond the plate beams on either side of the gable. Dawson’s photographs show how the vertical wall planks fit neatly into slots in both these gable plates and the base plates that ran along the ground. Sometimes the wall planks were bent by steaming and forced to overlap to produce a weather-tight wall. The six-beam system opened up the interior of the house, making its use more flexible, because interior free-standing house posts were no longer necessary.