Native softwood species are naturally not durable or not very durable, which is why they need to be treated in an autoclave to be protected against insects and putrefaction. Any wood which is kept outside has to be treated under pressure when its humidity is lower than 20-25 %.
All the timber that Huet treats gets systematically checked before impregnation (even in an autoclave, damp or frozen wood will not get penetrated properly by the treatment product which cannot enter into waterlogged cells).