Durability classes of different wood species


Classes	Type of wood
highest: 1	Ipe \| Teak \| Camaru \| Impregnated wood A class
2	Noawood
	Merbau \| Chengal \| Balau \| Iroko
3	Western Red Cedar (WRC) \| Siberian Larch \| Douglas Fir
4	Norway Spruce \| Scots Pine \| Douglas Fir
weakest: 5	Birch \| Aspen \| European Ash

Timber in durability class 2 is suitable for exterior applications above ground without the need for further treatment.