What is A5 / as-built documentation?

Compared to B2 and B3, A5 is relatively simple: it gathers what's already been documented along the way, in one final, closing step. It isn't the place where new control work happens - it's the wrap-up that shows the structural engineer that the overall picture holds together.

Precisely because it's simpler than the two preceding documents, it often gets deprioritised in planning - which can become a problem if B2 and B3 haven't been kept up either, because then there's nothing solid to gather from.

It's rare for a building to end up exactly as drawn, and that isn't a problem in itself. It only becomes a problem if the deviation isn't described and assessed in the A5 documentation - for example if a material choice or a dimension changed along the way, without the consequence for load-bearing capacity being documented.

A deviation can arise for many reasons: a supplier didn't have the specified material in stock, a detail proved impractical to build as drawn, or an error was caught and corrected along the way. What they all have in common is that they need to be described, assessed and approved - not simply noted in passing.

Because A5 builds directly on B2 and B3, it becomes hard to assemble if those two preceding documents haven't been kept up to date along the way. This is where most delays at handover actually arise - not in the A5 work itself, but in reconstructing missing parts of B2 and B3 before A5 can even begin.

In practice, this means A5 is rarely a standalone problem. It's a symptom of whether the rest of the documentation chain has been maintained correctly through construction.

The A5 documentation gathers an overview of the controls carried out from B3, a description of each recorded deviation and how it was handled, plus an overall assessment of whether the finished building meets the structural assumptions. The structural engineer uses this combined picture - not the individual B2 and B3 documents in isolation - to approve the building at handover.

The most effective way to ensure a smooth A5 process is to keep B2 and B3 up to date throughout construction, so A5 becomes a genuine wrap-up rather than a reconstruction. If you're already close to handover without a clear A5 plan, it's still possible to catch up - but it typically requires reviewing B2 and B3 thoroughly first, to work out what's actually missing.

On one project, it turned out during construction that a planned beam dimension wasn't available from the supplier within the schedule. The designing engineer was brought in, assessed an alternative dimension as sufficient, and the change was approved and documented in the B3 report before work continued.

In the A5 documentation, the deviation appears as a clear, pre-approved decision - not a surprise discovered only at handover. That's exactly the difference that decides whether a deviation is unproblematic or becomes an obstacle to approval.

If a deviation is only discovered at handover, without having been assessed along the way, the designing engineer has to assess it retrospectively - which can require supplementary investigation of the completed work before the structural engineer can approve the building. That's slower and often more expensive than ongoing approval.

The structural engineer typically checks whether every control point from the B2 plan has a corresponding result in the B3 report, whether any deviations are described and assessed, and whether the overall picture makes sense against the structure's assumptions. It's rarely individual details examined in isolation - it's the coherence between the three documents.

That's why the most common reason A5 gets sent back isn't an error in the A5 document itself, but inconsistencies between A5 and the underlying B2 and B3 documents.

A5 documentation has value beyond handover itself. If the building is later extended, altered, or sold, A5 is often the document a new advisor or buyer will ask for, to understand what was actually built and which deviations from the original project were approved along the way.

It therefore makes sense to keep the A5 documentation together with the building's other drawings and papers for the building's entire lifetime - not just for the period the DS1140 case was active.

On projects where DS1140 doesn't apply, handover typically happens without the same formal requirement for a complete as-built record of the load-bearing structure. That makes A5 something specific to DS1140-regulated projects - an extra level of thoroughness that isn't standard in an ordinary handover, but which delivers a far better-documented building to work with afterwards.

If it emerges late that a control point lacks documentation, and the relevant structure is already covered by subsequent work, a conservative assessment from the design engineer is usually the fastest way forward - supplemented by a destructive investigation if the assessment can't be made with sufficient confidence otherwise.

If an A5 case is rejected or delayed, it makes sense to spend some time identifying whether the cause lies in the A5 work itself, or actually originates from gaps in B2 or B3 earlier in the process. That insight is often more valuable for the next project than fixing the current case alone.

If it's unclear who is responsible for assembling the A5 documentation at handover - the building owner, the main contractor or an external advisor - it should be clarified early in the project, not just as handover approaches. Naming a responsible party for this specific task reduces the risk of it being overlooked amid the general busyness around handover.

A5 documentation goes more smoothly when it's treated as an ongoing task through the final phase of construction, rather than a single push in the last week before handover. Teams that leave it entirely to the end tend to discover gaps at the worst possible moment, when there's least time left to fix them.

Building A5 into the project's overall timeline, with a clear point at which it needs to be substantially complete, avoids this last-minute scramble.

Photographs are often the most useful part of A5 documentation, precisely because they capture a moment that will otherwise be permanently hidden once the next stage of work covers it. It pays to agree early who is responsible for taking these photos, and to what standard - a blurry, poorly labelled image is barely more useful than no image at all when the structural engineer reviews the file months later.

Once a recurring gap in A5 documentation has been identified on one project - missing photo evidence of a particular type of joint, for instance - it helps to build it into the checklist for the next project as a fixed item, rather than trusting the same mistake won't repeat itself. Systematically carrying lessons across projects is often what separates organisations with consistently strong A5 documentation from those where quality swings from job to job.