Technical Booklet D Structure·Page 36·4B.13
Rafter and purlin span assumptions
Rafter spans assume simple support between purlin and wallplate or between purlin and ridgeboard; purlin spans assume continuous rafters.
In the tables for rafters, the permissible clear spans are for rafters simply supported between a purlin and wallplate or between a purlin and the ridgeboard. However, in the tables for purlins, the permissible clear spans are based on the assumption that the rafters are to be continuous.
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