What is a B2 control plan?

For each control point, the B2 document must state the control type - how it's checked, for example visual inspection, physical measurement or calculation control. Next, the control level - how thorough the check needs to be, based on the building's structural class. And finally the control scope - how much of the structure is checked, and how often.

Miss any of the three, or describe them too loosely for someone on site to act on directly, and the structural engineer can't approve the plan. It's one of the most common reasons building projects stall early on.

Most rejections come down to one of three things. The control scope doesn't match the structural class - for example, spot-checks where the class requires systematic control. The control points are described too loosely for anyone to actually carry out the check against them - "check the joints" without specifying which ones, or how. Or the responsibility for each check is missing entirely, leaving it unclear who's actually meant to carry it out and document it.

A fourth, less common problem is that the plan was written against an incorrectly assumed structural class. This typically surfaces only once the engineer reviews the case, and usually means large parts of the plan need reworking.

The B2 plan is typically prepared early in the project - ideally before construction begins - based on the project material and the established structural class. It can be prepared by an advisor, by the contractor themselves, or jointly between several parties, but it always has to be approved by the certified structural engineer before control work on site begins.

Timing matters: a plan written only once the building is already underway can rarely cover control points that have already passed without documentation.

Once B2 is approved, self-inspection is carried out against the plan's control points - the contractor's ongoing, practical control work on site. The result is documented in the B3 control report, point by point. If the structural class requires it, an independent inspector also verifies whether the self-inspection holds up. B2 is, in other words, the starting gun - the rest of the DS1140 documentation builds directly on it, and a weak B2 plan carries through into everything that follows.

The most effective way to avoid rejection is to have the structural class clarified before the plan is written, not during. Beyond that, it helps to describe every control point specifically enough that someone on site can act on it directly, without having to interpret what's meant.

Finally, it makes sense to nam a responsible person for each control point from the start, rather than leaving responsibility informally shared between several people on site. That's often exactly the ambiguity that later shows up as gaps in the B3 report.

For a reinforced concrete slab, a control point in the B2 plan might read: control type is visual inspection of reinforcement placement before pouring, supplemented by cover-depth measurement. Control level is high, because a failure in the slab has serious consequences. Control scope is 100 percent of the reinforcement in that slab, not spot-checks.

A point like this gives the person on site a clear task - what to check, how thoroughly, and how much - with no room for interpretation.

A precise, well-structured B2 plan doesn't just avoid rejection - it also makes self-inspection faster on site, because the people carrying out the work know exactly what's expected of them without needing to ask. It similarly makes the structural engineer's later review of the B3 report quicker, since every entry can be checked directly against a clear, corresponding control point.

The time spent getting B2 right at the start is rarely wasted: it's recovered many times over in fewer questions, fewer disputes about what was actually required, and a smoother path to approval at handover.

Beyond being the document the structural engineer needs to approve, a good control plan also works as an internal management tool for the site team - it shows which control points remain open and can be used to schedule exactly when each control needs to happen on site. Used this way throughout the project, the plan becomes far more useful than a document that's only consulted once, at submission.

Teams that treat the plan purely as a formality tend to rediscover its content late in the project, at the point it's least convenient to act on gaps.

Although the control plan is primarily a technical document, it can also matter in a legal context if a dispute later arises over whether control was carried out as agreed. A precisely worded plan isn't only useful for the engineer's approval - it also serves as a clear reference point if the parties later need to agree on what was originally intended.

If the plan has been drafted internally, a colleague or an external advisor should usually read it through before it goes to the structural engineer. Whoever wrote the plan easily overlooks their own ambiguities, simply because they already know what was meant - a fresh reader spots far more quickly where a control point is actually described too loosely.

Whether the plan is kept in a spreadsheet, a text document or a digital app, the most important thing is that the structure stays consistent throughout - the same layout for every control point, all the way through the document. A plan that changes format or level of detail partway through is harder for the engineer to review systematically, even when the actual content is sound.

It's common for a project's actual conditions to diverge from what was assumed when the plan was first drafted - a supplier substitution, a design change, or a site condition nobody anticipated. When that happens, the plan should be updated and reissued to the structural engineer, rather than quietly worked around on site while the paperwork stays unchanged. An out-of-date plan is one of the most common reasons a submission gets sent back.

The plan works best when it's drafted from an actual walk-through of the building's load-bearing structure, rather than from a generic checklist applied without adjustment. A plan built directly around the specific building tends to need far fewer revisions once the structural engineer reviews it.

It pays to allocat real time to this drafting stage rather than treating it as paperwork to get through quickly - the plan sets the frame for everything that follows in the project.

Over the course of a project, small practical decisions on site can quietly diverge from what the plan describes, without anyone deciding to change the plan itself. Left unchecked, this drift is one of the most common reasons a B3 report doesn't match the B2 plan when the structural engineer compares the two at handover.

A short, regular check - comparing what the plan says against what's actually happening on site - catches this early, when it's still cheap to correct.

Before submitting the plan for approval, run a final check that every control point actually names a control type, level and scope - a point left vague, even briefly, is one of the most common reasons a structural engineer sends a plan back for clarification rather than approving it outright.