In excavations made in Lauenburg, Germany, there are indications that buildings were thatched with straw as long ago as 750-400 BC. In Denmark, this type of roof is believed to have been in use for at least 2000 years. The use of thatched roofs has decreased considerably; this is partially due to insurance companies demanding higher premiums for what is perceived as a high fire risk, and partially because of the mechanization of agriculture (straw that has gone through a combine harvester is unusable). In Germany and the Netherlands, reeds have almost become non-existent due to land drainage. In Western Europe today the raw material is imported from Poland, Bulgaria and Romania. Even Denmark has difficulty supplying its local needs. Conversely, in Africa and Asia, roofs built from local plants still dominate many cultures. In India, for example, 40 million houses are covered with palm leaves, reeds and straw.
Ecologically speaking, grass materials for surface applications are very attractive. They are renewable resources taken from uncultivated areas, or else by-products of agriculture and food production. The production processes do not require much energy or generate pollution.
In buildings, grass materials don't usually have problems. Building boards, however, often have adhesives added, such as polyurethane glue which can emit small amounts of unreacted isocyanates. Fresh linoleum can emit aldehydes. There has also been evidence of emissions from added solvents, glues and plastic-based surface coatings if these have been used. The differences in these emissions can be large, depending on the manufacturer.
As waste, the pure products can be composted or burned for energy recovery. When composted, special care should be taken to avoid eutrophication of ground water. For products containing adhesives, special waste treatment and incineration is required.
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