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Popular Media Promotes COFI’s Horizontal Diaphragm Design Manual for Dimension Lumber in Post & Beam Housing

Hidehiko Fumoto

By Hidehiko Fumoto

Deputy Director and Manager Technical Services, Canada Wood Japan

March 8, 2018

With 45,000 copies distributed to retail book stores nationwide, “Kenchiku Chishiki” is the most popular architectural magazine in Japan.  The magazine’s special feature in the March 2018 issue is wooden roof structures for post & beam houses.  In the context of roof structural design method, it reports that COFI’s structural design manual is the answer to the challenges that many structural designers are facing – to use dimension lumber as roof rafters in post & beam houses.  The article addresses the technical hurdles for dimension lumber use in “Greybook”, known as the most important design guide for wooden structural calculations in post and beam, which fails to specify dimension lumber sizes in the chapters dealing with roof and floor diaphragms.  To overcome this issue, Canada Wood developed a structural design manual which enables builders and architects to specify dimension lumber sizes in Japanese post and beam roof and floor assemblies.  To date we estimate that more than 70 structural engineers in Japan are currently using the manual in their daily design work.  The feature article of “Kenchiku Chishiki” is expected to accelerate the popularity of the manual.