Deformation-accurate as-built survey

A deformation-accurate as-built survey does not only capture the intended geometry of a building. It precisely documents the actual condition, including deformations, deviations and unevenness. It is used in particular for historic buildings, existing structures and complex renovation projects where real geometries differ from idealized plan dimensions. Unlike a simplified measured building survey, a deformation-accurate as-built survey documents the actual building geometry as a reliable basis for planning, fabrication, existing building renovation and as-built documentation.

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Why is a deformation-accurate as-built survey important?

• Capturing real building structures: Leaning walls, deflections or settlements are documented precisely.
• Reducing planning risks: Surprises during conversion and renovation work are minimized.
• Enabling custom-fit fabrication: It provides the basis for individual components, facade elements or interior fit-out.
• Supporting heritage conservation: Historic buildings can be documented in detail and in a traceable way.
• Creating reliable BIM models: The digital model represents the actual existing building instead of idealized geometries.

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When is a deformation-accurate as-built survey required?

• Listed or heritage-protected buildings: Historic structures often show deformations that have developed over decades or centuries.
• Renovation and conversion: In existing buildings, available plans often no longer match the actual condition.
• Facade and roof renovations: Even small deviations can cause significant installation problems when prefabricated components are used.
• Industrial buildings and complex existing structures: Large spans, settlements or previous conversions often lead to geometric deviations that are relevant for planning.

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How a deformation-accurate as-built survey is created in practice

1. Data Capture

The geometry is captured using high-precision measurement methods, for example:

• Terrestrial laser scanning (TLS)
• LiDAR systems
• Photogrammetry
• Tacheometric surveying

2. Quality Assurance

The measurement data is registered, checked and reviewed for completeness.

Important criteria include:

• Documented tolerances
• Checkpoints and control measurements
• Traceable data registration

3. Evaluation

The actual building geometry is analyzed and modeled in a deformation-accurate way.

This includes, for example:

• Inclinations of walls
• Deflections of ceilings and slabs
• Deformations of roof structures
• Settlements and unevenness

4. Derivation of Results

Depending on the project, the following outputs may be created:

• Deformation-accurate as-built plans
• Facade elevations and developments
• CAD models
• BIM models
• Digital twins

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Typical Mistakes

• Deformations are smoothed or simplified during modeling.
• The required accuracy is not defined before the project begins.
• Existing planning documents are adopted without verification.
• Measurement data is not quality-assured sufficiently.
• The desired level of detail is not coordinated.

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