What is a B3 control report?

Where the B2 plan sets out what needs to be checked, the B3 report follows the plan's points one by one and records when each control was carried out, who carried it out, and what the result was - approved, or a deviation with a description of how it was handled.

The connection between the two documents is tight: if a control point from the B2 plan is entirely missing from the B3 report, neither the structural engineer nor any independent inspector can see whether that point was checked at all.

Most building cases that run into trouble here are missing exactly this ongoing update. It typically happens because responsibility for documenting the control is spread across several people on site, with no overall picture - and the gap is only discovered once the structural engineer reviews the report close to handover.

Another common cause is that the control is actually carried out, but never written down clearly enough to be usable: the date or executing party is missing, or the control point isn't clearly matched to the corresponding point in the B2 plan.

Not all control ends in a simple "approved". If the executing party discovers a deviation - incorrect dimensions or the wrong material, for example - it needs to be recorded in the B3 report along with a description of how the deviation was handled and what consequence it has for the structure's load-bearing capacity.

A well-documented deviation is rarely a problem in itself. It only becomes a problem if the deviation isn't recorded, or if it only surfaces in the A5 documentation at handover, without having been addressed along the way.

The most reliable solution is to gather the documentation in one place and match each point directly against the B2 plan, as work progresses - rather than trying to reconstruct the process afterwards, once the structural engineer asks for it.

It also helps to make documentation a fixed part of the executing party's workflow, rather than an administrative task handled separately and often too late. The closer documentation sits to the actual control work, the smaller the risk that a point falls through the cracks.

When we take over a case with an incomplete B3 report, we start by comparing it against the B2 plan to see which specific points are missing. In many cases, the missing points can still be documented - either because the work can be re-inspected, or because other documentation exists that can serve as a basis.

For each control point in the B2 plan, a well-kept B3 report includes the date of the control, the name of the executing party, a short description of what was checked, and a clear result. If there's a deviation, it's described concretely - for example "reinforcement spacing measured at 28 mm against a planned 25 mm, assessed as having no effect on load-bearing capacity by the designing engineer".

A report like this lets the structural engineer follow the whole process without having to ask about individual parts - which typically speeds up approval.

More construction firms have started keeping the B3 report digitally, with photos and timestamps taken directly on site, rather than gathering paper notes afterwards. That reduces the risk of a control point being forgotten or documented unclearly, because the recording happens while the control is carried out - not the day after.

Besides the structural engineer, the building owner often has an interest in following the B3 report on an ongoing basis, particularly on larger projects, to keep an overview of how far the control work has progressed. Insurance companies may also request it in connection with a damage claim, where it's relevant to be able to document that the control was actually carried out as planned.

That's another reason to keep the report updated on an ongoing basis, rather than treating it as an internal working document that only matters at handover.

If, at some point after handover, damage arises that could relate to the load-bearing structures, the B3 report is often the first thing an insurance company or an independent assessor will ask for. A complete, clear report makes it possible to quickly establish whether the structure in question was checked as planned.

That's yet another reason to keep the B3 report together with the rest of the building's documentation for many years after handover - not just for the period construction was underway.

The construction teams that least often run into gaps in the B3 report have usually made documentation part of the working day itself - a short daily check where the day's completed controls are reviewed and logged, rather than letting it pile up for a weekly or monthly clean-up. That daily routine tends to matter more than the specific tool chosen to record it.

It makes sense to distinguish between a formal control of a named point from the B2 plan, and a general observation a worker makes on site without it relating to a specific point. Both kinds of information can be useful, but only the first belongs in the B3 report as a formal control - mixing the two together makes it harder for the structural engineer to see whether every point in the plan is genuinely covered.

If different trades use different tools to document their part of the B3 report - one an app for concrete, another a spreadsheet for carpentry - it pays to agree early how the different sources will be combined into one coherent report at handover, rather than discovering late that the formats don't fit together.

If you work with an international workforce, it helps to make sure the control points in the B3 report can be correctly understood by everyone who needs to document them - an unclear translation of a technical term can, in practice, lead to a control point being documented incorrectly without anyone noticing until the structural engineer reviews the case.

It should be clear from the B2 plan or the overall agreement who is responsible for retaining the finished B3 report after handover - the building owner, the main contractor, or an external party. Without that clarity, there's a real risk that none of the parties actually takes on the long-term storage, even though everyone assumed someone else was handling it.

Setting the reporting rhythm at the very start of the project - who logs what, and how often - saves considerable friction later, because everyone involved already knows the expectation rather than discovering it partway through. Teams that leave this undefined tend to see reporting quality drop as the project gets busier, exactly when it matters most.

A short kick-off conversation covering just this point is usually enough to establish the habit for the rest of the project.