Expanded Opportunities for Dimension Use in 30 Minute P&B Fireproof Structures
The Wooden Home Builders Association of Japan (WHBA), consisting of the leading Post & Beam housing companies, has obtained a 30 minute fireproof roof/floor structure MLIT Ministerial Approvals. Generally speaking, Post & Beam housing uses traditional Japanese lumber sizes in roof and floor applications and tend to be exclusive of Canadian dimension lumber sizes. This is one of reasons that it is difficult for Canadian dimension lumber to be used in Pose & Beam structures in Japan. Canada Wood Technical Manager Yusuke Neriko has been working with the WHBA technical committee to facilitate broader acceptance of dimension lumber sizes in post and beam housing.
Several years ago the WHBA commenced a project and established a technical committee to obtain Ministerial Approvals for roof and floor diaphragms in post and beam fireproof structures. Yusuke Neriko participated in the committee from the beginning, and convinced committee members and consultants to add Canadian dimension lumber to the specification and succeeded. 204, 206, 208, 210 can be used as rafters and joists in the new MLIT ministerial approvals. While the standard thicknesses for rafters and joists typically have a minimum of 45mm, Canada Wood was successful in having a minimum 38mm thickness specified. Thanks to these ministerial approvals, Canadian dimension lumber now has new opportunities to be used in fireproof Post & Beam housing.