Timber house Demolition waste can be a toxic problem...
The above illustration shows the enormous and growing volume of material produced from housing demolition carried out after the Christchurch Earthquakes. This disaster occurred in a small city of a 350,000 population. The demolition material shown represents demolition of less than 5% of the local housing stock and less than 20% of the expected demolition volume.
While certain materials can be manually removed, the predominant material by volume is timber. The timber waste is considered contaminated, containing various toxic preservatives and other materials. Therefore it cannot be safely buried, burnt or processed as fuel as this will contaminate natural soils, aquifers and air quality. Demolition timber also contains rot, funguses and insect damage and therefore cannot be practically or economically re-used in any worthwhile manner.
On the other hand concrete waste has proven useful in providing clean fill to greatly expand the local shipping container terminal. This expansion reclaims areas of natural harbour, with the demolition waste passing stringent environmental management requirements as a suitable material. Reinforced concrete has proven itself as an entirely recyclable material with reinforcing steel locally recycled into new steel products and crushed concrete used as both safe fill and aggregate for other new concrete and building uses.
The information, data and illustrations that disaster events produce can inform thinking of how buildings and structures are designed and built, and reveal that it is the process of Design at the front-end that can define how and where materials are sourced and how they are used in ways that can help eliminate redundant future waste.