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Designing Out Construction Waste – Tactics to Employ

Finding uses for waste, diverting it from landfill, is valuable but it is surely preferable to avoid creating that waste in the first place? The construction sector is a priority for Scottish Government so it worth knowing that it is possible to design buildings which will generate almost no waste over their lifetime if we really want to.

The key is to anticipate the likely changes when designing all aspects of the building. There are four main groups of tactics to employ.

 

Adaptability

Most buildings are not demolished because they are structurally dangerous or have some other fundamental technical problems, but because it is not economic to adapt them to new layouts and aspirations. The most effective tactic we can employ as designers therefore to avoid demolition waste, is to anticipate potential changes and make this as easy as possible – reducing both waste and costs in the future. Adaptable buildings allow for different layouts to be easily created, in turn allowing for a wider variety of potential uses of the spaces.

Examples include:

  • Anticipating possible extensions to a building, in particular this affects site latyout and location of corridor or access routes
  • Arranging building layouts to be used in different ways, grouping serviced zones and considering adjacencies in association with structural lines
  • In individual rooms dimension and design in access to services to allow for different layouts, including the careful placement of windows and doors, such as in the attached sketches
  • Building in extra height in section, which would allow for future adaption to include raised floors or dropped ceilings in future.
  • Limiting structural intrusion into a space, – minimise or group columns to give more flexibility in a space.

Layering and Access

Components in a building can only be repaired or replaced if they can be accessed and, where necessary removed. Much of the waste lying in skips across the country wasn’t the material that needed to be upgraded, it was the fabric that needed to be removed to get at the material to be removed. Buildings can be designed to avoid this sort of waste by anticipating what might need to be accessed and making that easy, without the need for disruption and waste. Incidentally, this also future-proofs building owners against potential future costs.

The diagram shows how this can be achieved conceptually, and this gives rise to a variety of tactics such as:

  • Access hatches and cover plates at places to hidden services
  • Service access rooms, such as between public toilets with all cisterns and pipework accessible
  • Entirely removable – and replaceable – surfaces allowing free access to spaces behind
  • Designing components to be removable from a safe place (eg from inside rather than from a scaffold). This includes ensuring that fixing points are accessible too.
  • Allowing tolerance and space to remove items – ensure they are not tightly butted to surrounding framework for example.
  • Allowing for replacement of parts of a layer due to wear and tear, or weathering. Forward thinking companies like Interface not only allow for simply removable carpet tiles, they also design the patterns to make it more difficult to tell worn tiles from new ones.

Components

Most components in theory could be reused or recycled, but it is rarely economical for anyone to actually carry this out, and disposal charges remain low. Our role as designers is to make it as easy and cost effective as possible to reuse or recycle everything we specify. Components should be:

  • Durable – robust enough to be removed whole and undamaged.
  • Standardised – making it easier for them to be reused in other places, or interchangeably.
  • Easy to Handle – bricks and blocks are safe and easy to handle, large components needing specialist lifting gear may be technically removable, but it is unlikely that it will ever be cost effective to do so.
  • Higher value materials and components which are financially worth repairing and reusing are clearly more likely to find their way into new projects.
  • Repairable – many commonly used materials and components are not cost-effective to repair if they are damaged.
  • Some components are polymeric and too strongly glued together, making each part unfeasible to reclaim, whereas monomeric options may exist for the same role.
  • Coatings can extend the life of some materials but can severely disrupt the potential for reuse or recycling
  • Toxicity in materials and components, often added for added functionality (like fire, stain or decay resistance) may in future represent a burden as environmental legislation increases costs associated with disposal
  • Biodegradable or compostable building materials can be used for almost every conceivable part of a building and clearly represent a zero waste option even if they are otherwise impossible to repair or reuse
  • Some companies operate leasing schemes in which they will take back and reuse / recycle their products
  • Reused and recycled components of course represent an improvement on alternatives using virgin or mostly virgin materials. The key however, is to ensure that these materials or components have a service life into the future as well…

Fixings

Components are often fixed together with far more mechanical or adhesive strength than is really needed. In order for components to be cost effectively repaired or reused, it has to be easy to remove them. Tactics include:

  • ‘Non-fixings’ such as gravity or friction fittings, as well as magnetism (for example as used on certain secondary glazing systems)
  • ‘Weak fixings’ such as mortars which are weaker than the components (like lime mortar) or the ‘Tac-tiles’ provided by Interface carpets which avoid spreading adhesive across the whole floor
  • Reusable or compostable mixes which represent a zero waste option
  • Durable fixings which are robust enough to be removed and reused several times
  • Mechanical fixings which can be undone: screws in preference to nails, bolts in preference to welds and rivets
  • It helps greatly if the fixings, and tools needed are standard types

Chris Morgan is a Director at John Gilbert Architects in Glasgow. This article is based on material provided for Resource Efficient Scotland for their publication ‘Designing Out Construction Waste’ available from https://www.resourceefficientscotland.com/Construction/design-out-waste

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