Timber Design A timber building, using timber floor joists spanning 5.0m, are required to be loaded for a duration of medium-term loading. The timber floor with total dead loads of 1.55 kN/m' and 1. imposed live loads respectively is to be constructed on a simply supported timber floor joists of grade GS, Caribbean Pitch Pine. Ignoring the joists self-weight, select an adequate section to support the above loads for the joist which are spaced at 400mm centre to centre. The sections are also to be checked for bending, deflection and shear capacity.