Abstract: A prefabricated wall unit for log building construction is produced on a specially-constructed assembly frame by sequentially stacking a plurality of individual log units co-planarly and joining each log unit in sequence to the previously stacked log unit by lag bolts driven through the log units to integrate the logs in the wall unit. Longitudinal studs are affixed in relatively spaced relation to one side of the integrated logs and supplementary insulation is sprayed between the studs. A plurality of wall units are vertically arranged in relative abutting relation on and affixed to a conventional building foundation to produce a log structure, the wall units being joined to each other by the interdigitation of respective log units of abutting wall units and the driving of lag bolts through such interdigitated log units.