TOKYO, Japan --  The Ministry of Land, Infrastructure and Transport has suggested a large-scale draft revision of the notification on technical standards for building log houses. The major point of the revision will be expansion of building types that the log house method will be allowed to construct.

Under the current standards, construction of log houses are limited as follows; 1) buildings shall be lower than two stories excluding basement floor, 2) total area shall be less than 300 square meters and 3) height of buildings shall be lower than 8.5 meters.

The revised standards will show more detailed conditions that will be permitted: 1) Two-story log houses being lower than 8.5 meters in height that use an attic as the second floor; 2) two-story wooden mixed structure--houses built by the log house system on the first level and by wooden post & beam or 2x4 method on the second; 3) three-story mixed structure of reinforced concrete or steel frame on the first level and log house engineering on the second story and above, whose third floor is an attic; 4) two-story log houses; 5) two-story houses of mixed structure--the first level is built by log house method and the second story is built with combination of log system and wooden post & beam (or 2x4).

In case that overall area is more than 300 square meters or that a building meets the conditions from the (2) to (5), the structural safety shall be proven in accordance with calculation of allowable unit stress.