Planning for Deconstruction
The amount of material that can be salvaged for reuse or recycling is largely dependent on the type of building being deconstructed, time constraints and the local recycling market. Good planning will help to improve salvage and reduce waste.
Planning for deconstruction includes:
- undertaking an initial assessment of the site and building to determine whether the building will be a good candidate for deconstruction - this includes assessing the cost-benefit of deconstruction versus demolition
- developing an inventory of materials and finding out what materials are recyclable or reusable and, if possible, arranging prior sales for salvaged and recyclable material
- ensuring sufficient time is scheduled for deconstruction
- developing a deconstruction plan
- training staff and subcontractors prior to working on site to maximise the volume and quality of materials salvaged.
An initial assessment of the building and the site will help identify salvage opportunities. At this stage, consider whether to sell the whole building or dismantle and sell individual parts.
Types of buildings likely to be good candidates for removal for reuse are structurally sound (i.e. generally weathertight to minimise rotted and decayed materials, and with minimal borer damage) and able to be removed from the site (protected trees or other buildings may hinder removal).
Examples of buildings that currently have a market for reuse include greenhouses, steel-framed warehouses, temporary buildings and houses that are good specimens e.g. timber-framed villas.
Types of buildings likely to be good candidates for deconstruction
- Timber-framed with heavy timbers and beams, or with unique timbers.
- 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.
- Constructed with high-quality brick laid with low-quality mortar (to allow relatively easy break-up and cleaning) - ensure that mortar strength meets the minimum requirements from a standard such as ASTM C39-86 Compressive strength of mortar.
- Commercial buildings constructed using high-quality reusable items such as steel beams and steel cladding.
- Some types of concrete tilt-slab construction
A review of paperwork to determine types of materials, construction techniques and the location of all services is a good place to start. Review plans, working drawings, and engineer's reports obtained from your city or district council or from your client. The architect or engineer may have already prepared a deconstruction plan that includes a list of building materials and components (as well as their design or service life and the best options for reuse, refurbishment or recycling) and instructions on how to deconstruct elements.
Site survey and building assessment
A survey of the site should be made to determine whether the building will be removed for reuse or deconstructed, and to identify salvage opportunities and hazardous materials.
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.
- Tradesperson 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 client and/or the design team may also want to be part of the assessment.
Tools you'll need to perform a building assessment include:
- 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 should be worn whenever any cutting, drilling or removal of materials is done.
Document the following information using the REBRI Waste Management Plan:
- Develop an inventory of types and quantities of materials to be salvaged, recycled or disposed of and determine markets for materials prior to the project starting.
- Determine costs and savings associated with reuse, recycling and disposal. Make sure you include payment for recyclables and reusable materials, reduced landfill/cleanfill disposal costs, transport costs, and time required for sorting or preparing materials for reuse or recycling.
- Identify components from the old building for reuse in the new building. Compile a detailed list to pass to relevant contractors.
- Photograph joinery and other building components in place prior to removal to indicate potential reuse and to give purchasers a better idea of how the joinery would look in place.
The amount, type and condition of materials salvaged is affected by the time available to do the work and the methodology and sequencing of deconstruction. To maximise recovery rates and avoid contaminating or damaging materials (which then precludes reuse), it is important to:
- use plans and working drawings to help determine how to deconstruct using reverse construction sequencing
- ensure adequate time is scheduled for deconstruction methods
- explain to clients that, because deconstruction involves careful planning and preparation and is more labour intensive than demolition, more time is required.
Have a plan for the project that aims to maximise resource recovery.
Collate all the deconstruction planning work into the REBRI Waste Management Plan or adapt it to your own business. The plan can then be used when tendering for contracts, to provide staff with information on the project and can be included as part of the application for a building consent, required for demolition of all buildings in New Zealand.
The plan should include:
- quantities of materials to be salvaged for reuse, recycled and sent for disposal.
- destination and/or intended end use of the buildings 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 of materials handling and removal procedures, particularly on project sites with space constraints.
Training demolition staff and subcontractors is a key success factor for high recovery of building components. By understanding the process of transforming demolition materials into valuable products, workers take more care in recovering as much material as possible while ensuring minimal contamination. Most training in the industry is done on the job, so your training programme should reflect this.
Consider these things:
- Ensure employees and subcontractors are aware of what they need to do and how they should do it. Consider providing documentation on resource recovery requirements, deconstruction techniques, and sorting and storage requirements.
- Formalise the roles of senior staff as trainers, and provide any training to enable them to be more effective on-the-job trainers.
- Emphasise the benefits of deconstruction and maximising resource recovery.
- Ensure accurate identification and planning for hazardous substances - the increased manual nature of deconstruction means that this is even more important. Occupational health and safety advisers may be able to assist.
- Consider using a formal job training programme through industry training organisations and/or apprenticeships.
- Consider the mix of staff experience on any project, to ensure less experienced staff are mentored and managed by more experienced staff.
- Check documentation regularly and keep a record of training.