Deconstruction versus demolition. What is the best option?
Sustainability awareness has rapidly changed the way we think about demolition. What was once a sector dominated by heavy machines and piles of rubble is now a space where we think more strategically about the salvageability of materials and our impact on the environment.
Investors, builders and developers now have a choice when faced with removing an old structure from a project site: demolition or deconstruction?
Demolishing buildings
Demolition involves the familiar process of razing a structure in such a way that its components are reduced to manageable piles of waste. The process is often preferred when working with a tight budget or a strict project deadline. Knocking a building down is quicker than dismantling and it requires less manual labour. It allows a project site to be cleared quickly, and can contribute to a more efficient construction process.
Demolition, however, presents a challenge for recycling and sustainable construction. Rubble can be collected and processed into construction products like aggregate, road base or crusher dust, but the demolition process is less discriminatory and there is a high probability that potentially recyclable materials are mixed with untreatable or hazardous waste.
The value of deconstruction
Deconstruction, or ‘unbuilding’, uses labour and sometimes mechanical equipment to disassemble structures and salvage building materials, firstly for reuse and secondly for recycling. Some of the key materials that can be salvaged and recycled for future use include:
bricks and concrete
terracotta tiles
wood products like trusses, framework and floorboards
good quality fixtures and fittings.
Deconstruction significantly reduces the amount of construction waste that goes to landfill. This is important because construction and demolition are major landfill contributors. According to the National Waste Report 2020, 3,137 kilotonnes of masonry materials generated from construction and demolition went to landfill in 2018-19. Construction and demolition overall contributed 27 million tonnes of waste, or 44 per cent of the total core waste generated in the same period[1].
Deconstruction, however, requires a greater time investment than demolition. According to the NSW Environment Protection Authority, deconstruction takes 55-60 per cent longer than demolition[2]. This is because recyclable materials need to be removed and separated, and materials that can be sold for reuse must be handled carefully to ensure their quality for the next project. This often requires more labour time and specialised machinery, which can impact project timelines.
However, there are four key benefits to deconstruction that makes it an increasingly popular option:
Companies can save on the significant disposal and transport costs associated with sending waste to landfill, while conserving landfill space and extending the life of landfills.
Salvaging recyclable building materials reduces the demand for raw material and resource extraction.
Deconstruction can help the economy. Providing recycled alternatives can create more jobs and lower the cost of building materials for the community.
Companies that deconstruct buildings and recycle materials gain goodwill and can market their sustainable approach to environmentally aware customers and investors[3].
Key considerations for demolition and deconstruction
Whether demolition or deconstruction is the best option depends on several factors:
Time and cost. What is the project timeframe? How will deconstruction affect timelines, and how will demolition and disposal affect project costs?
On-site health and safety. How big is the site: will heavy machines be able to manoeuvre? What type of structure is involved? Does it contain hazardous materials, or an abundance of recyclable materials?
Company reputation. Could an environmentally-savvy waste disposal strategy, which includes salvaging materials, improve your company’s reputation in the eyes of customers and industry partners?
The environment. What type of impact will your company have on the construction industry, and the environment, by choosing either to demolish a building or salvage its materials?
The choice between demolition and deconstruction is ultimately based on how these factors impact a project; however, the economic and environmental benefits of recycling has shifted the way we think in the construction industry. Construction and development will always generate waste, but it’s become increasingly important to consider how much waste we generate and what we do with it.
[1] https://environment.gov.au/system/files/pages/5a160ae2-d3a9-480e-9344-4eac42ef9001/files/national-waste-report-2020.pdf
[2] https://www.epa.nsw.gov.au/-/media/epa/corporate-site/resources/managewaste/100080-house-deconstruction.pdf?la=en&hash=CD70BEEF7EC72CEBC3641F46F1DBE19862DAED1D
[3] https://www.epa.nsw.gov.au/-/media/epa/corporate-site/resources/managewaste/100080-house-deconstruction.pdf?la=en&hash=CD70BEEF7EC72CEBC3641F46F1DBE19862DAED1D