How point clouds relate to BIM
Laser scanning records points on visible surfaces. Those points form a point cloud, which can be linked into authoring software as an existing-condition reference. Creating a usable BIM model is a separate task that involves interpreting and modeling the agreed elements.
Existing drawings remain useful. They may describe concealed construction, previous alterations or design intent that a surface scan cannot show. The project team should compare the available records, scans and site investigations rather than assume one source is complete.
Using BIM for demolition planning
1. Documenting existing conditions
A model can show the geometry captured by the survey and help the team identify differences from record drawings. Its reliability depends on scan coverage, registration, modeling tolerance and the information supplied for concealed areas.
A point cloud does not by itself identify material strength, hidden reinforcement or structural deterioration. Those questions need appropriate investigation and professional assessment.
2. Communicating the proposed sequence
Views and staged models can help explain removal areas, retained elements, access routes and temporary works. They give the team a common reference for reviewing the plan and recording unresolved questions.
The model supports communication; the competent project team still needs to develop, check and control the demolition method.
3. Coordinating machinery and retrofit work
Geometry can help teams review equipment envelopes, access and potential interferences. Navisworks Manage clash detection can report conflicts between selected model elements or point clouds.
Geometric clearance is different from load capacity. The weight a floor or support can carry requires engineering evaluation of the actual structure and loading. A scan or clash report does not supply that approval.
Keep the engineering assessment separate
For work covered by U.S. OSHA demolition rules, 29 CFR 1926.850 requires an engineering survey by a competent person before employees begin demolition. It also addresses matters such as utilities and damaged structures. A digital model does not replace those requirements.
For scan-to-BIM drafting, agree on the source data, modeled elements, tolerances, exclusions and review process. Identify unverified or inaccessible areas so the demolition and engineering teams can decide what further investigation is needed.
