Sadoline microporus used to be bloody brilliant dad bought a new tin 2/3 years back guess what it's now low VOC
and lasted one season (on his bench that he's had forever and repainted every 5 years or so with a jar of old formula stuff he begged off a old school joiner shop he used to deliver to until he run out and retired and unable to waltz in and beg some more 
Real killer of sheds is the tongue not been treated well as this rots away first been trapped in the groove it takes a long time to dry out
Guttering and down pipes increases life too
