Applicability conditions for timber member design

The dimensions of a timber member may be determined by this Section where – (a) the dead and imposed loads to be sustained by the floor, ceiling or roof of which the member forms part, do not exceed the values given in the appropriate diagrams and tables; (b) the species and grade of timber for the strength class to which the table relates is either – (i) as given in Table 4B.1 for more common species; or (ii) as given in the more comprehensive tables of BS 5268: Part 2; (c) the timber is service class 1 or 2 and is clearly marked "Dry" or "KD" (kiln dried); and (d) floorboarding complying with BS 1297 is used.