Material Use

More waste is produced when a home is demolished than at any other stage in its life. Significant waste is also generated during renovation/remodelling of a home. The most effective way to minimise waste is to prolong the building’s life by relocating or refurbishing it, incorporating old materials where sound into the new.

By planning ahead and ensuring through contract documentation that care is taken during the deconstruction/demolition process, a significant amount of waste can be diverted for re-use or recycling.

Top tips for minimising waste during demolition/deconstruction

Before a design that involves deconstruction/demolition is started:

• assess the site and building – where a building’s demolition is proposed, determine whether the building can be relocated and, if it can’t, make an inventory of materials and consider what can be re-used in the new building, what can be re-used elsewhere, and what can be recycled
• find markets for materials that can be re-used or recycled
• write a plan to document your intentions
• discuss your intentions with your client – make sure the client is aware of the costs and benefits involved.

During deconstruction/demolition:

• allow enough time within contract periods for dismantling
• identify on a site plan clearly marked storage areas for each type of material – these should be located so they are convenient for workers and provide protection from the weather and from other sources of potential damage
• specify dismantling components in reverse order to construction
• specify that the soft strip of interiors is done manually to reduce damage
• specify that all latches, hinges, framing etc are kept with the window, door or other building component
• specify that all salvaged items are to be removed carefully from the site to reduce damage and contamination.

After deconstruction/demolition, market any salvaged items that haven’t already been sold. Use the Yellow Pages, industry directories (from the Recycling Organisation of NZ and Waste Management Institute of NZ websites) or trade magazines and websites.

Site/building assessment

1. Review of plans and other paperwork

The next step is to review plans, working drawings, and engineers’ reports obtained from the local council or your client. This will help to determine the types of materials and construction techniques used, and the location of all services in the existing building.

2. Building survey

A survey should be made to determine whether the building will be relocated or deconstructed, identify materials and components that can be salvaged, and identify any hazardous materials.

Buildings that are structurally sound can be relocated, so long as it’s practical to move them. There’s a market for good timber-framed/timber homes, as well as for other types of building such as greenhouses and temporary buildings.

Types of buildings that are likely to be good candidates for deconstruction include:

• wood-framed buildings with heavy timbers and beams, or with unique woods
• buildings constructed with specialty materials such as native or hardwood flooring or wall timbers, multi-paned windows, architectural mouldings, and unique doors or plumbing/electrical fixtures
• buildings constructed with high-quality brick laid with low-strength mortar (to allow relatively easy break-up and cleaning)
• buildings incorporating high-quality re-usable items such as steel beams or steel cladding.

Consider involving some of the following people in the building assessment:

• builder, carpenter, architect or anyone with expertise in the methods and materials of construction
• tradespeople experienced in repair/restoration of equipment, appliances, materials
• structural engineer/materials inspector who can provide information on the structural integrity of building components and/or the existence of hazardous materials requiring special handling
• someone who has a good understanding of the salvage value of building materials in the local market.

The following tools may be useful when performing a building assessment:

• inspection forms – to ensure that you have collected all the information you need
• camera – photographs can be helpful in recalling important characteristics of the building and the site
• hand/power tools – it may be useful to look behind walls or beneath flooring to verify the size and condition of structural components or the existence of hazardous materials
• respirators or dust masks – these must be worn whenever any cutting, drilling or removal of materials is done.

As part of the building assessment, make an inventory of materials. Each material type should be quantified using industry standard units of measurement. Evaluate each material to determine whether it should be:

• salvaged for reuse
• recycled
• disposed of.

Determine the costs and savings associated with re-use, recycling and disposal. Include payment for recyclables and re-usable materials, reduced landfill/cleanfill disposal costs, transport costs, and time required for sorting or preparing materials for re-use or recycling.

3. Deconstruction plan

The architect or engineer should prepare a deconstruction plan that includes:

• a final list of building materials and components that must be removed for reuse within the new design, removed carefully but not for reuse within the new work, or sent to recycling
• the specification for the refurbishment work to be undertaken
• instructions on how to deconstruct elements.

Document the information in a deconstruction plan. This can be used when tendering for contracts, to provide staff with information about the project, and as part of the application for a building consent for demolition. The plan should explain:

• quantities of materials to be salvaged for reuse, recycled and sent for disposal
• destination and/or intended end use of the building’s various components, including appropriate disposal of residual waste
• deconstruction methodology and sequencing
• schedule for deconstruction
• location, security and protection of storage areas (if materials are to be stored on site – clearly mark location of all storage areas on a site plan if this is available
• details on materials handling and removal procedures, particularly on project sites with space constraints.

The REBRI website has a downloadable template for a waste management record (PDF, 624 kb)    .

For your clients

To help your clients understand the benefits of reducing construction waste, refer them to www.smarterhomes.org.nz/construction.