Pre-redevelopment audit or structural survey

Pre-redevelopment audit vs structural survey is a comparison worth getting right, because the two documents answer different questions and a scheme that commissions one instead of the other usually finds out late. The audit records what the building is made of, so that material can be reused or recycled and hazardous substances identified before anyone starts breaking things. The structural survey assesses whether the frame and fabric can carry what you intend to put on them. One is about materials and risk. The other is about capacity.

On a refurbishment with a retention argument you will need both, and the sequence matters more than the cost of either.

What each document is for

A Pre-redevelopment Audit is an inventory. It records the quantities and types of material in the existing building, identifies which elements can be reused in situ, which can be reclaimed for use elsewhere, which are recyclable and which must be treated as waste. It also flags hazardous materials so that removal is planned rather than discovered.

A Structural Survey is an appraisal. It records the form of construction, the condition of the elements, evidence of movement, deterioration and past alteration, and it assesses whether the structure has capacity for the proposed use and loading. Where records are absent, it identifies what testing and opening up is needed to establish that capacity.

The overlap is narrow but real. Both look at the same building and both need access. Neither substitutes for the other, and a structural report that lists materials is not an audit, because it has not quantified them or considered their fate.

What each survey physically involves

The audit is largely a measuring and recording exercise. A walkover with drawings, element by element quantification, sampling where the construction is uncertain, and limited opening up to confirm build-ups behind finishes. Much of the quantity data comes from the drawings where record information survives, which is why the audit is quicker on a building with a good archive.

The structural survey is more intrusive. Visual inspection first, then opening up at agreed locations to expose connections, reinforcement and bearings. On a concrete frame that may mean cores for compressive strength, carbonation depth and chloride testing, cover meter surveys and reinforcement location. On a steel frame, connection exposure and material sampling to establish grade. On masonry, mortar analysis and wall tie investigation.

Both need access to the same places and both benefit from the building being empty. Coordinate the opening up schedule so that one set of access arrangements serves both, and so that the same opening is not made twice.

Asbestos and other hazardous materials

This is where the audit earns its keep, and where it interacts with a separate legal regime. The Control of Asbestos Regulations 2012 require a suitable and sufficient assessment of whether asbestos is or may be present before work that may disturb the fabric. For demolition or refurbishment, that means a refurbishment and demolition survey, which is destructive and has to be carried out by a competent surveyor.

The audit and the asbestos survey are different documents with different competence requirements, and the audit should reference the asbestos survey rather than attempt to replace it. Beyond asbestos, the audit should identify lead paint, deleterious materials in the original specification, refrigerants and oils in retained plant, contaminated ductwork, and any material that changes the waste classification of the arisings.

Timing is the practical point. A refurbishment and demolition asbestos survey is normally carried out once the building is vacant, because it involves breaking into the fabric. So the audit can start earlier, but the hazardous materials picture is not complete until vacant possession, and the demolition package cannot be priced accurately before then.

Reuse and retention arguments in a planning case

Retention is now a planning argument rather than only a cost argument, and both documents feed it.

Where a policy requires a circular economy approach, the audit supplies the evidence base. Quantities, reuse proportions and destinations are what a Circular Economy Statement is built on, and a statement that offers percentage targets without an audit behind it will be treated as aspiration.

Where embodied carbon is in issue, the audit feeds the existing building baseline and the structural survey establishes what can honestly be retained. A Whole Life Carbon Assessment comparing a retrofit option with a demolish and rebuild option is only credible if a structural engineer has confirmed which retention option is buildable. An assessment that assumes full frame retention where the survey shows the slabs cannot take the loading is not a comparison of real options.

The corollary is that a demolition case needs the same evidence. Where the argument is that the building cannot reasonably be retained, the structural survey is the document that says so, and it has to say so on the basis of investigation rather than assertion.

Timing relative to the design freeze

Both should be complete before the design is frozen, and in practice the structural survey has the earlier deadline.

1. Desk review of record drawings, previous surveys and any archive material, at the outset.
2. Structural visual inspection and a preliminary view on retention capacity, before massing is settled.
3. Pre-redevelopment audit walkover and quantification, running alongside.
4. Opening up and testing at agreed locations, once access allows.
5. Structural appraisal with capacity conclusions, feeding the design and the carbon comparison.
6. Refurbishment and demolition asbestos survey, on vacant possession.
7. Audit finalised with hazardous materials and destinations, feeding the waste and circular economy documents.

The error that costs most is freezing the massing before step two. A scheme designed on an assumption of two additional storeys, then surveyed, is a scheme that may have to be redesigned after the planning drawings are complete.

Who is competent for each

They are different professions. A structural appraisal of an existing building belongs to a chartered structural or civil engineer with experience of appraisal rather than of new design, and the professional institution's guidance on appraisal of existing structures is the reference point. Appraisal is a distinct skill, because it involves judgement about structures built to superseded codes with incomplete information.

The audit is usually carried out by a sustainability consultant, a quantity surveyor or a demolition specialist, and there is no protected title. Ask what method and reporting format will be used, and whether the quantities will be presented in a form the carbon assessor can use directly.

Asbestos surveying has its own competence regime, with accreditation and individual qualification, and you should ask for both. An audit author who offers to include the asbestos survey without that accreditation is offering something they should not.

Combining them on a refurbishment

Practical coordination saves more than negotiating either fee. Appoint both before the design is frozen, with a single access and opening up schedule. Require both to work from the same drawing set and the same element numbering, so that element 12 means the same thing in each report. Ask the structural engineer to identify which opening up locations would also serve the audit, since the engineer's locations are driven by structural logic and the auditor's by material distribution.

Then require a single combined schedule of interventions, listing every opening, its purpose, who attends and how it is made good. On an occupied building that schedule is what the tenant will actually be shown, and it is what keeps the survey programme from stalling.

One honest limitation. Both documents are based on sampling, and both will carry caveats about what could not be inspected. Where the caveats cover something the design depends on, resolve it before submission rather than treating it as a construction risk, because an unresolved retention assumption is exactly what turns into a section 73 application later.

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. For specialist technical reports, qualified professional input may be required, and both a structural appraisal and an asbestos survey are work councils and regulators expect suitably qualified authors to carry out.

Browse the report types on PlanScope to see how the audit, structural and carbon documents fit together on a refurbishment.