What are the best BIM strategies to capture irregular geometries and deteriorated elements in historic façades?

For historic façades, the most reliable strategy is to start with high-density LiDAR scanning. It captures all the irregularities, sagging lines, and deformations that old buildings always have. Photogrammetry works great as a supplement, especially for capturing carved details, cracks, or texture loss that scanners may miss.

Once you have the point cloud, avoid “forcing” perfect geometry. Keep an as-is model and a cleaned model:

The as-is version preserves all the distortions for documentation and conservation.
The cleaned BIM version simplifies only what’s needed for design, analysis, or clash checks.

Also helpful: tag deteriorated zones directly in the BIM model (cracks, spalling, displacement), so conservation teams can quantify areas and link repair notes.