(a) Applicability. The rules in this section apply to the transportation of bundles of dressed lumber, packaged lumber, building products such as plywood, gypsum board or other materials of similar shape. Lumber or building products which are not bundled or packaged must be treated as loose items and transported in accordance with §§393.100 through 393.114 of this subpart. For the purpose of this section, “bundle” refers to packages of lumber, building materials or similar products which are unitized for securement as a single article of cargo. (b) Positioning of bundles. Bundles must be placed side by side in direct contact with each other, or a means must be provided to prevent bundles from shifting towards each other. (c) Securement of bundles transported using no more than one tier. Bundles carried on one tier must be secured in accordance with the general provisions of §§393.100 through 393.114. (d) Securement of bundles transported using more than one tier. Bundles carried in mor