Recycling advisory group Wrap has released a guide on using materials from demolished buildings to build those repalcing them. Its head of waste minimisation talks us through the new document

The construction industry creates 120 million tonnes of waste every year. Only half of this is recycled, with most turned into aggregates. Wrap, the recycling and materials advisory group, aims to change that, and this week launched a guide to help clients, designers and contractors maximise the reused and recycled elements of their buildings. Phil Wilson, construction project manager for waste minimisation at Wrap, gives us a sneak preview.

What’s different about the Wrap guide?

It draws on the Institution of Civil Engineers’ demolition protocol, site waste management plans and Wrap’s Quick Wins recycled contents approach, and integrates them into a common framework.

It is intended as a toolkit for clients, contractors and designers working on regeneration projects that involve demolition and new build.

What are you trying to achieve?

We’re trying to link demolition and new build for regeneration projects. In other words, getting the buildings being pulled down to contribute materials to the ones going up in their place.

Is recycling and re-use cost effective?

There is a business case. Money can be saved because of the lower price of using recovered materials as well as by avoiding waste disposal charges, landfill tax and transport costs. One case we looked at, Langley Park Homes in Kent, saved £480,000 by reclaiming the roof tiles and recycling the concrete of the existing buildings – that was 3.5% of the project cost.

There are also environmental and social benefits, such as less traffic to site. The CTRL avoided 8,000 lorry journeys to and from central London by recycling on site.

What is the starting point?

The design team needs to draw up a list of the type and quantity of materials that can be recovered. This information can be gathered during a pre-demolition audit or using knowledge of similar projects. A list can then be produced of what can be used in the new build, on site and elsewhere. Planning should take place at the design stage, with the demolition contractor.

What can contractors and specifiers do?

About 10-15% of materials ordered end up in skips, in the form of off-cuts, and over-ordered and damaged products. Architects and engineers can address this by sizing and designing buildings to reduce off-cuts and the variety of materials used.

They can reclaim elements such as drains, foundations, facades, frames, beams and roof tiles for re-use. If design is considered early, it can make use of existing elements.

Off-site construction is also a good way to reduce waste as the process is much more controlled. It also means elements can be delivered to site just in time, which reduces risk of damage and the need for packaging.

What should happen during demolition?

The key to success is giving the demolition contractor enough time. A soft strip on site during demolition can be used to recover things such as architectural features, light fittings and sanitaryware. The segregation of waste, such as metal, glass, timber and plastic avoids contamination and double-handling, and allows efficient recovery and lower disposal costs.

How do you ensure it happens?

The guide outlines indicators to assess performance. The demolition recovery index is a KPI that describes the efficiency of material recovered and is based on the weight of the recovered material divided by the total weight of the demolished materials.