This guide supports preliminary discussion. It is not a structural assessment, subsurface investigation, repair design or statement that a particular treatment is suitable.

1. Define the observed response

Record where movement is visible or felt, the loading that triggers it, and whether the response occurs at joints, cracks, edges or within a panel. Map affected and apparently unaffected areas using a consistent reference system.

  • Note the date, operating condition and applied load during each observation.
  • Record cracking, joint condition, surface level differences, pumping, water paths and previous repairs.
  • Separate audible response, measurable deflection and permanent level change.

2. Keep several mechanisms open

Possible contributors may include incomplete support, erosion or migration of fines, shrinkage or consolidation of supporting material, drainage defects, construction discontinuities, changing loads, or deterioration within the slab and joints. The presence of a void does not by itself identify why it formed or whether it is still developing.

3. Select evidence for the decision

The investigation should follow the question. If the decision depends on the extent of suspected loss of support, coverage and correlation matter. If it depends on structural capacity, the slab system and loading require separate engineering consideration.

  1. Review drawings, floor loading and repair history.
  2. Complete a systematic condition and level survey.
  3. Use appropriate non-destructive methods to identify patterns and targets.
  4. Correlate interpretation with known features or proportionate confirmation where required.
  5. Document uncertainty and areas where access or material conditions limit confidence.

4. Define boundaries before intervention

A treatment scope should state the target zone, intended function, interfaces, access constraints, service risks and exclusions. Filling a detected space and correcting the cause of support loss are not necessarily the same task.

5. Agree verification in advance

Set baseline observations and measurable acceptance criteria before work. Depending on the objective, verification may include controlled response checks, levels, material-consumption records, injection logs, repeat survey data and post-work monitoring. The chosen checks must match the promised outcome.

Continue to verification planning →