Timber gone grey might look innocuous enough..

.. but
'UV radiation actually damages wood fibers. This process renders them less resilient and more prone to cracking or sloughing off. If left long enough, UV radiation will cause board warping, cracking, and cupping.'

The cladding alongside the barn had not weathered at all (7 years old). But this end was exposed to sunlight and had gone grey and was also covered with algae.
We stripped it back by various means both chemical and mechanical and now has 2 coats of wood preserver just like what we did all along the back, and will be getting two coats of Osmo protection oil.
Should last longer than we will...
Must be time for an ice-cream..