The revision this time includes setting up of type A and type B for structural LVL. Type A is former structural LVL and type B allows more insertion of orthogonal layers.
By former rule, a percentage of orthogonal layers have to be less than 20% and insertion place has to be second layer from outside then the new rule says a percentage of orthogonal layer in thickness is less than 30% and it allows to insert into third layer from outside.
This prevents warping and curving of LVL and improves precision to make products for use as panel. Specifically, it works better for stressed skin panel (SSP- hexahedron beam) and wider board over 1,200 mm.
As to insertion of orthogonal layer, new standard follows the European rules since SSP is widely used for large furniture stores and roof of airport buildings. Compared to steel, it makes roof weight much lighter, which simplifies construction of base parts and reduces construction cost.
The new rule stipulates standard of cave-in performance (maximum of 18N/square millimeter/vertical use of type A only) so that it can be used for foundation of mid-rise buildings and lower frame of 2x4 buildings.
Classification of bending performance of structural LVL had ten classifications from 180 E to 60 E then the new rule adds lower grade of 50E in focusing use of domestic cedar.
There is potential use of LVL for interior with its unique design but fire proof performance is necessary in case of exposed use. It is necessary to have the Minister’s approval if it is used as panel so the Japan LVL Association made performance test in September to acquire quasi-fire proof approval on cedar product (30 mm in thickness, 150 mm in width and 4 meters in length).
The application has been submit to the Ministry of Land,
Infrastructure and Transport and the approval of the Minister can be obtained early next year.