Stage 1: Pre-demolition Audit

Demolition material can be integrated with a future works programme or at least be considered for use in other building projects.  A walkthrough example is provided for the Pre-demolition Audit (211 kb) , the audit forming an important part of the overall project management process.  It does so by identifying resources which can be recovered for future use rather than being lost to landfill. 

The walkthrough example takes the user through the detailed steps which allow the following to be established:

• The potential of a building to be assessed for maximum material recovery.
• A Demolition Bill of Quantities (D-BOQ) to be produced, which identifies tonnages and potential applications of materials.
• A Demolition Recovery Index (DRI) to be created from the D-BOQ, providing a quantifiable measure of the potential for recovery of the materials.
• An informed approach to material segregation, considering the potential impacts of contamination and cost benefits.

Information on the above is now provided in summary form below.

It should be noted that the HSE, Training & Risk Assessment (61 kb)  document provides information on how health & safety, training and awareness of contractors will also influence the resource recovery operations associated with demolition.

Resource Recovery Methodologies

In terms of resource efficiency the ICE Demolition Protocol is a key driver for more effective demolition methodologies. It allows a linkage to be made between the new build and demolition stages of developments, providing supply and demand mechanisms for demolition material recovery and the procurement of recovered materials.

Detailed requirements may be set in a variety of ways for demolition good practice, for example, through planning conditions and tender & contract clauses.  Examples of tender and contract clauses can be found in the Procurement Module.

The National Green Specification (NGS) has prepared a number of specification clauses to support the delivery of best practice.

Demolition Bill of Quantities (D-BOQ)

The D-BOQ allows the following to be determined:

• The Demolition Recovery Index (DRI)
• Demolition Recovered Material Potential (DRMP)

The DRI and DRMP allow the potential for recovering material from a building to be expressed in terms of a percentage and tonnage, respectively.  A target is then set for recovering demolition material based on the following:

• The cost benefits associated with the landfill, reclamation and recycling of materials
• The potential for contamination

This will then inform the preferred approach to material segregation and result in an assessment of the site layout to manage segregated material streams.  The Demolition Recovered Material Target (DRMT) can then be established.

As mentioned at the top of the page, the Pre-demolition Audit walkthrough example describes the steps required to produce the DRI & DRMP and DRMT. A template is also provided here illustrating the headings to be used for the D-BOQ.

• NB-BOQ & D-BOQ Templates (58 kb)  

Resource Recovery Plan

Managing Contamination: Two types of contamination should be identified with a view to potential impacts on resource recovery potential:

• Physical Contamination: the approval of recycled aggregates from demolition material in applications such as road sub-bases has required developing an awareness of the testing regime, and permissible organic, timber or gypsum content, frost-heave performance etc. In concrete, the physical contamination requirements of BS 8500 relate to maximum levels of fines, lightweight, material, asphalt, foreign material and acid soluble sulphate. 
• Chemical Contamination: is mentioned here mainly with regards to the potential for specifying demolition recyclate in concrete products. There are four main chemical contaminants regarding concrete. They are alkali/silica, carbonate, chloride and sulphate. There are limits for each of these potential chemical contaminants in concrete, and therefore it is important that these are considered to ensure that the material produced from demolition sites is uncontaminated and suitable for specification in high performance applications.

The Historical Building Use and Chemical Contaminants table in the ICE Demolition Protocol allows an assessment to be made of the contamination risks posed by different types of buildings. If there are potential contaminants associated with the building, use of the risk assessment flow charts in the Protocol facilitates the process of determining where to segregate contaminated from uncontaminated material.

Cost Benefit Analysis: The segregation of demolition materials can take place once a simple cost benefit analysis has been carried out to assess the level of segregation which makes economic sense.

A cost benefit analysis template is provided in the walkthrough example mentioned at the top of the page.  Completion of this will allow effective resource management practices (with clear financial benefits) to be identified. This could be achieved, for example, through approaches to soft-strip, segregation and recycling. 
 
Segregation & Soft Strip: The Resource Recovery Plan can complement the development of Site Waste Management Plans (SWMPS), which are currently a voluntary (soon to be compulsory as of April 2008) requirement  of the Clean Neighbourhoods and Environment Bill (2005). 

A number of pressures influence how material can be managed:

• Space constraints around and near to the site - see the Demolition Site Layout Plan;
• Timescales, i.e. the need for a fast-track project will impact on the potential for carrying out innovative approaches; 
• Financial incentive & markets; 
• Proximity to other properties such as residential, commercial buildings.

The soft strip methodology should strive to maximise the potential of materials, first for reuse, and secondly for recycling. The materials removed to allow access to concrete and masonry will often have value and should be assessed as such.

Download Pre-demolition Audit (211 kb)  section of the 'Implementing Best Practice' document

Download HSE, Training & Risk Assessment (61 kb)  sections of the 'Implementing Best Practice' document