4×4 Ft black Ground nstruction mats 100 tons load capacity TN-9 Load Tables for l&Bea - Twin Creeks Log Home S The design loads for 4x4 and 4x6 lumber for the mm used grades are listed in Table 2, and for incised lumber in Table 3. Tables 4, 5, and 6 ntain design loads for 6x, 8x, 10x and 12x timbers.