Pre-demolition audits and reuse expectations in London

A pre-demolition audit records what is in a building before it comes down: the materials and components, their quantities, their condition and whether each one can realistically be reused rather than crushed. In London it is the evidence base for the circular economy case on a referable scheme, and it has to be done while the building is still standing and accessible. Commission it late and the audit becomes a desk exercise with estimated quantities, which is the version a Greater London Authority officer will send back.

The London Plan expects very high recovery rates for construction and demolition waste and for excavation material, and it expects retention of existing structures to be considered before replacement. The audit is how both arguments are made.

What the audit is expected to record

Think of it as a measured survey of material rather than of space. For each element of the building it should record the material, the quantity in tonnes or square metres, the condition, the method of removal, any contamination or fixing that prevents clean separation, and the proposed destination.

A usable audit covers:

• Structure: concrete, structural steel, timber frame, masonry, with quantities by element
• Envelope: cladding panels, curtain walling, glazing, insulation, roofing
• Internal fabric: partitions, doors, ironmongery, raised floors, ceilings, joinery
• Services: boilers, chillers, air handling units, lifts, cable, pipework and sanitaryware
• Hard landscape: paving, kerbs, walls, railings, boundary treatments
• Hazardous materials, identified through the separate asbestos survey required under the Control of Asbestos Regulations 2012

The destination column is where the audit earns its place. Reuse in situ, reuse elsewhere on the site, reuse off site by a named route, recycling into a lower value product, or disposal. An audit that marks everything as recycling has not been done properly.

Surveying materials before demolition

The survey needs access, time and someone who knows what reclaimed material is worth. Three practical points shape the result.

Access while the building is occupied is limited, so programme the survey into the vacant period between the last tenant leaving and the demolition contractor arriving. That window is usually short and usually missed.

Fixing methods determine reuse potential more than material type. Bricks laid in lime mortar can be reclaimed; bricks in cement mortar usually cannot. Bolted steel connections allow deconstruction; welded and encased sections rarely do. Record the connection, not just the component.

Traceability matters for structural reuse. Reused steel sections need documented provenance and testing before they can be used structurally again, and the cost of that process is part of the comparison with new material.

A pre-redevelopment audit is the document that carries this work, and it should be dated and tied to a site visit rather than assembled from drawings.

Reuse on site against off site

On-site reuse is almost always the better outcome, and the reason is transport. Crushing concrete on site for use as sub-base avoids two lorry movements per tonne, which shows up in the carbon numbers and in the construction traffic.

Off-site reuse fails for logistical reasons rather than technical ones. Careful deconstruction takes longer than demolition, reclaimed material needs storing somewhere, and there has to be a buyer at the point the material becomes available. Where off-site reuse is proposed, say who will take it and when.

How findings feed the circular economy case

The circular economy statement is the submission document for referable schemes, and the audit supplies its numbers. The statement should move from the audit to commitments, expressed as rates and tonnages rather than aspirations.

Four things make it credible. A quantified baseline from the audit. A stated percentage of arisings to be reused or recycled, with the split between the two shown separately because they are not equivalent. Named routes for the highest value material. And a design response, showing where the new building itself has been designed for disassembly, with reversible connections and standard component sizes.

The retention argument belongs here too. Where the scheme demolishes a structure that could have been retained, the statement has to explain why, and a bare assertion about floor to ceiling heights or structural grid will not carry it.

Links to the carbon assessment

The audit and the whole life carbon assessment draw on the same information and are often prepared by different teams, which produces inconsistencies an officer will notice.

Reuse reduces embodied carbon in the product stages of the new building, and demolition arisings appear in the end of life stages of the existing one. Benefits from material leaving the site for reuse elsewhere are reported separately rather than netted off the headline figure, which is a reporting convention worth getting right because netting it off inflates the result.

Keep one quantity schedule and have both documents reference it. Where the carbon assessment assumes 90 per cent recovery and the circular economy statement claims 95, someone has to explain the difference, and it will not be at a convenient moment.

Securing commitments by condition

Expect a condition requiring the circular economy commitments to be implemented, and a further requirement to report what was actually achieved after completion. That reporting obligation is the part developers underestimate, because it needs data collected during demolition by a contractor who was appointed before anyone mentioned it.

Build it into the procurement:

1. Include the audit and the stated recovery rates in the demolition tender documents
2. Require waste transfer notes and weighbridge tickets by material stream, not a single total
3. Require monthly reporting against the committed rates during demolition
4. Name the person responsible for collating the post-completion report
5. Keep the asbestos and hazardous waste records separate and complete

A site waste management plan is the document that organises this on site. The regulations that once made such plans compulsory in England were revoked, but the document remains the practical way to deliver and evidence a condition of this kind, and several authorities ask for one.

Reporting what was actually achieved

The post-completion report compares the committed rates with the measured outcome, stream by stream, and explains any shortfall. Officers read the explanations.

Two patterns recur in weak reports. Totals that cannot be reconciled with the waste transfer notes, and a reuse figure that turns out on inspection to be recycling. Both are avoidable with a reporting template agreed before demolition starts.

And one honest point: reuse rates for structural material remain low across the industry, and the market for reclaimed components is thin in some streams. A statement that commits to a modest, deliverable amount of genuine reuse with a named route reads better than one promising a large figure with no mechanism behind it.

Browse the report types to see which circular economy and carbon documents a London redevelopment is likely to need.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.