Pre-redevelopment audits and what they have to record

A pre-redevelopment audit records what an existing building is made of, in what quantity and in what condition, and where each of those materials and components could go if the building is taken down or stripped out. It is produced before any decision about demolition is finalised, which is the point: an audit written after the demolition contractor is appointed has no influence on anything. The output is an inventory with quantities, a condition assessment and a set of identified routes for retention, reuse, recycling or disposal, together with an estimate of what proportion of the building by mass can realistically be kept in use.

It is a different document from a site waste management plan. The audit looks backwards at what exists. A Site Waste Management Plan looks forward at the waste the construction process will generate.

What the audit is for

Three things drive the requirement. The first is circular economy policy, which is most developed in London, where the London Plan requires referable applications to address waste and the circular economy and the Mayor's guidance expects a pre-redevelopment audit where demolition or substantial strip-out is proposed. The second is whole life carbon, because the embodied carbon already in a structure is only counted as avoided if the material is demonstrably retained or reused. The third is more prosaic: demolition arisings have value, and an audit done early turns a disposal cost into a materials budget.

The audit also provides the evidence for the option appraisal that officers increasingly ask for, comparing retention and refurbishment with demolition and rebuild. Where that comparison is not done, a scheme can be asked to justify demolition at committee without any figures to hand.

Surveying the existing building fabric

Walk the building with the drawings and expect them to be wrong. Record what is there element by element: substructure, frame, floors, external walls, roof, windows and external doors, internal walls and partitions, finishes, fittings, mechanical and electrical plant, lifts, external works and hard landscape.

For each element, capture material type, quantity, dimensions where components could be reused whole, fixing method, accessibility for removal, and condition. Fixing method matters more than anything else in the survey: a brick wall in lime mortar can be dismantled and the bricks reused, the same wall in cement mortar usually cannot. Bolted steel comes apart, welded steel does not.

Intrusive investigation is needed for the parts that matter. Opening up a sample of floors, soffits and wall build-ups is the only way to know what the construction actually is, and the audit should state clearly which findings are from inspection and which are inferred.

Hazardous material surveys run alongside and are not optional. A refurbishment and demolition asbestos survey is required before work that will disturb the fabric, under the Control of Asbestos Regulations 2012, and the findings change what can be reused. Lead paint, treated timber, deleterious insulants and contaminated plant all have the same effect.

Recording quantities and material condition

Quantities should be given in units that a reuse market understands: tonnes for aggregate, masonry and metals, square metres for sheet materials and finishes, linear metres for timber sections, and item counts for components such as doors, sanitaryware, radiators, luminaires and structural steel members.

Condition is best reported on a simple consistent scale with the criterion stated, for example whether a component is reusable as is, reusable after refurbishment, suitable for recycling only, or suitable for disposal only. Add a confidence rating, because a roof that has not been opened up carries a different level of certainty from a steel frame that has been surveyed and tested.

Keep the inventory as a spreadsheet with a stable element reference, and report the summary in the planning document. An audit submitted as 80 pages of prose with no schedule is unusable by the people who need it.

Identifying reuse and recovery routes

The hierarchy is the same everywhere, and the audit should test the options in order:

1. Retain the element in situ, which avoids the carbon and the cost entirely.
2. Reuse it on the same site in the new scheme, which needs the design team to commit early.
3. Reuse it off site, which needs a named market, a buyer or a reclamation route.
4. Recycle it into a new product, which is where most concrete, brick and glass ends up.
5. Recover energy from it.
6. Dispose of it.

Options two and three are where audits are weakest. Saying material "will be reused where practicable" commits nobody. Naming the element, the quantity, the proposed destination and the decision date does. For structural steel in particular, reuse depends on traceability and testing, so the audit should record what documentation exists for the original material.

Retention is worth modelling properly even where it looks unattractive, because the carbon saving is large and the detailing consequences are manageable. Where a structure or facade is kept, the thermal upgrade becomes the live design question, which is why thermal bridging detail at planning stage belongs in the same conversation.

Reporting formats councils expect

Where an authority has adopted a format, use it. In London that means following the Mayor's guidance structure so the audit sits alongside the Circular Economy Statement and the Whole Life Carbon Assessment and uses consistent figures across all three. Inconsistent tonnages between the three documents is the most common review comment.

Outside London, there is usually no prescribed format, and a proportionate structure works:

• a description of the building and its construction, with the survey method and date
• the element-by-element inventory, with quantities, condition and confidence
• hazardous materials summary and its effect on reuse
• the options appraisal, with the retention case tested
• committed reuse and recovery routes, with quantities and destinations
• a headline recovery rate by mass, with the exclusions stated
• what will be reported after completion

Give one figure prominence: the proportion of the existing building by mass that will be retained in situ or reused, with the basis of calculation shown. That is the number officers quote.

How the audit feeds the circular economy strategy

The audit is the evidence base, and the circular economy strategy is the commitment. The strategy should carry forward the specific items the audit identified, say where they will be used in the new building, and set out the design decisions that enable future disassembly of the new structure: mechanical fixings over adhesives, exposed services, standard component sizes, and a materials record for the completed building.

Where quantities change between the audit and the strategy, explain why. A reviewer comparing the two documents will notice.

A Pre-redevelopment Audit drafted as a structured document with the inventory schedule attached is the practical output. PlanScope produces the narrative, policy framing and reporting structure from your answers about the building, and flags every quantity it does not have so the surveyor's figures go into the right places. Reports should be reviewed before submission, and PlanScope does not guarantee planning approval.

Conditions requiring post-completion reporting

Expect a condition requiring a post-completion report comparing what was actually retained, reused, recycled and disposed of against the audit and the strategy, supported by waste transfer documentation. Waste duty of care records are the usual evidence, and they need to be collected as the work proceeds rather than reconstructed afterwards.

Two practical measures make that condition survivable. Set up the record-keeping in the demolition and enabling works contract, with the contractor obliged to report by element rather than by skip. And agree the reporting template with the case officer before commencement, because a condition that asks for a comparison against the audit is much easier to discharge when both documents use the same element references.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. For specialist technical reports, qualified professional input may be required.