Waste wood of category IV is defined as wood treated with wood preservatives or which – due to its pollution level – cannot be assigned to the categories A I, A II or A III. This substance group includes wood assortments, the wood preservation treatment of which has been determined by means of analyses or has to be assumed due to its origin. Even if a wood preservative treatment is visible (staining) or sensory (odour), this points to A IV wood.
The best-known category IV waste woods include railway sleepers and utility poles as well as hydraulic engineering timbers. But also windows and outside doors, garden furniture, timber framework, rafters as well as construction and demolition timber from outdor areas can be found in this category. Cable drums whose date of manufacture is before 1989 are also classified as A IV wood.
Waste wood of category IV can only be utilised in licensed large power plants ( 17th Ordinance for the Implementation of the Federal Immission Control Act). Category IV waste wood is considered hazardous waste and must be shipped with proof of disposal.