European Oak has a long tradition of use in the UK left unfinished and allowed to weather to a natural silver grey, in which state it has lasted for many centuries without maintenance.
External Cladding - Fixings should be designed to allow some movement to avoid splits developing, e.g. oversize screw holes etc, and be of non-ferrous or plated steel to avoid staining. The surface finish is likely to develop small checks and some moisture movement will take place in the sections. Oak dries very slowly with a marked tendency to split and check, particularly in the early stages of drying, there is also considerable risk of tanning exudation in the first year of exposure
75 years +