A Turning Point in Retrofitting Projects: Flawless As-Built Documentation and Cost Management with Laser Scanning

Increasing the seismic safety of existing building stock and structural retrofitting projects are among the most critical areas of the construction industry. However, retrofitting a structure is a far more complex process than building from scratch. The most painful and error-prone phase of this process is documenting the existing condition, or the as-built survey. At this point, where traditional methods often fall short, 3D Laser Scanning (LiDAR) technology is changing the rules of the game with its millimeter precision and cost-effectiveness.

1. Millimeter Precision: Capturing Deformations

Measurements made with traditional tape measures and laser distance meters are prone to human error and tend to "idealize" the structure (e.g., assuming a column is perfectly vertical or a beam is straight). However, buildings undergoing retrofitting often exhibit settlements, torsion, or section loss due to corrosion.

3D Laser scanners capture millions of points per second, creating an exact digital twin (Point Cloud) of the structure. This technology documents:

• Plumb deviations in columns and beams,

• Deflections in floor slabs,

• Irregularities in walls with a precision of ±1-2 mm.

Ideally fitting retrofitting shear walls or steel jacketing to the existing structure is only possible with this level of detail.

2. Cost Effectiveness: The Hidden Cost of "Cheap" Surveying

Laser scanning services may appear more costly than traditional survey crews at first glance. However, this is a misleading comparison. A flawed survey taken with traditional methods leads to steel elements not fitting during installation, formwork blowouts, or the need for on-site cutting and adjustments.

Laser scanning technology eliminates the following costs:

• Re-mobilization Costs: Since the entire building is scanned completely, there is never a case of "we forgot to take a measurement."

• Manufacturing Errors: Retrofitting elements pre-fabricated in the factory fit 100% when they arrive on site.

• Time Loss: Measurement processes that would take days on site are completed in hours.

3. Speed and Safety

Taking surveys in damaged or risky buildings can be dangerous for technical personnel. Since laser scanners can collect data remotely, they can capture details of the riskiest columns or beams from a safe distance without requiring personnel to enter dangerous zones. Furthermore, scanning thousands of square meters is completed 70% faster than traditional methods, allowing for a rapid transition to the design phase.

4. BIM and Digital Integration

The collected point cloud data can be directly exported to BIM (Building Information Modeling) software such as Revit or Archicad. This allows the engineer designing the retrofitting project to work not just on a 2D plan, but on the 3D reality of the structure. Clashes between existing installations (electrical, mechanical) and structural elements are detected right at the desk.

Conclusion

Using laser scanning technology in retrofitting projects is not a luxury, but an engineering necessity. A correct project cannot be designed with incorrect data. Considering the millimeter detail, speed, and error-free production process, laser scanning systems provide significant savings in the total project budget and an increase in quality.