An as-built plan documents the built state of a building as of a particular plan revision – as a drawing, scan or PDF in the archive. A survey checks that state on site and re-measures it. Between the two lies the question that decides every project on existing buildings: how far can the plan be trusted, and where must one measure?
In short
- The plan is a document with a date; the building has changed since or was never built exactly that way.
- The survey is the measurement – laborious, but binding.
- A screening from the plan sorts out where measuring is worthwhile.
Definition
As-built plans come from different stages: permit design, construction documentation, as-built record drawings (“as built”). Only the last are meant to show the actual state, and even they only as of their creation. Deviations arise from unrecorded changes during construction, later conversions, the difference between shell and fit-out dimensions, distorted scans, and plans without a dimension chain whose scale has to be estimated.
The survey replaces assumptions with measurement: manual measurement, total station or laser scan deliver room dimensions, heights and the actual fit-out state – quantities that no floor plan carries. It is the basis for binding documented proof such as a signed living area calculation.
Distinction
| Criterion | As-built plan | Area screening | Survey |
|---|---|---|---|
| Source | archive (drawing, scan, PDF) | the as-built plan, evaluated | the building on site |
| Result | rooms and areas as of the plan revision | areas per room with a flag where the plan is uncertain | measured rooms, heights, fit-out |
| Effort | already available | minutes per plan | hours per dwelling or floor |
| Reliability | document, not state | working basis | evidence |
In practice
A housing company with thousands of floor plans cannot survey everything and should not believe everything. The practicable rule: evaluate all plans, compare the results with the existing areas from lease or ERP, and measure where the deviation is large or the plan source uncertain. A survey is always mandatory when a figure carries legal weight – lease, service charge statement, disposal – and the plan predates the last conversion.
Anyone working from the plan documents plan revision and source per room so that the line between “from the plan” and “measured” stays visible – in the room book as its own column.
Normraum relevance
Normraum works with the as-built plan as it sits in the archive – scan, PDF or photo – and turns it into rooms and areas under DIN 277 or WoFlV with confidence and source reference. That is screening and a working basis, not a survey: what the plan does not show – later conversions, heights, fit-out state – no software can read from it. The check log flags where the plan source is uncertain and a survey becomes necessary.