Last edited 05 Jun 2019

Deconstruction

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Contents

[edit] Introduction

Deconstruction has been defined as ‘construction in reverse’. As construction involves assembling and erecting buildings, so deconstruction is the complete opposite: it involves taking buildings apart piece by piece, avoiding damage by extracting carefully what is required. This contrasts with demolition which tends to be a relatively arbitrary and destructive process, although generally quicker. Falling materials, noise, nuisance and dust often accompany conventional demolitions, not to mention large amounts of waste.

A building may be deconstructed if it is located in a sensitive area and its demolition would involve danger to the immediate vicinity, or if it has been designed for deconstruction so that its parts can be re-used or recycled.

[edit] Benefits

Deconstruction offers the following benefits compared to demolition:

[edit] Why deconstruct?

Deconstruction allows the reuse of materials, which is more environmentally friendly and results in less waste going to landfill – this is critical as construction and demolition waste can comprise up to 20% of all solid waste that ends up in landfills. In addition, some materials may have become more valuable at the time of deconstruction than they were during the original construction, such as some types of brick, decorative cast iron and so on.

When materials are reused/recycled, the resulting building can have less embodied energy and so a smaller carbon footprint. Designing for deconstruction (DfD) requires that designers focus on sustainability, durability and lifecycle analysis, especially when choosing materials and ensuring that the construction process does not render future deconstruction an impractical process. High quality materials integrated into a construction that is as simple as possible can be effective as well as avoiding the use of techniques that rely on nailing and adhesives.

Deconstruction may also keep alive traditional building crafts, such as the use of lime mortars and stone dressings. Furthermore, it can provide opportunities for trainees and apprentices to learn how buildings are put together and to gain skills, such as in basic carpentry, critical thinking and teamwork.

However, not all materials can be salvaged for reuse. Of these, some can be recycled on- or off-site otherwise they may have to be taken to landfill, while hazardous materials, such as asbestos and lead paint, require expert disposal.

Deconstruction tends to be a labour-intensive process given its selective nature. It can take weeks to harvest materials from a structure, whereas demolition can be completed in as little as a day.

A typical deconstruction process involves first removing windows, doors, appliances and finishes from the structure, much of which may be reused or resold. Then the structure is dismantled, usually from the roof, through the middle floors, down to the foundations.

[edit] DfD design principles

Ten common principles of design for deconstruction are:

[edit] Timber

Timber lends itself to easier reuse than say, brick, stone or metal. The benefits of avoiding timber waste mean fewer disposal costs, a reduction in greenhouse gas emissions (methane) from decomposition. The process typically has a 33% efficiency rate: it is estimated that every three square-feet of deconstructed timber will yield around one square foot of new timber construction.

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