Records
Review drawings, previous investigations, repair history, loading changes and dated reports. Record gaps and uncertain provenance.
Technical insights
Diagnose the mechanism before selecting the intervention.
Cracking, rocking slabs and uneven levels describe what can be observed. They do not, by themselves, identify why movement occurred or which response is suitable.
Start with the question
Is the issue in the slab, the support below it, or the foundation system?
Similar surface symptoms can result from different mechanisms. A preliminary review should separate the affected element from the possible loss of support, then test the working hypotheses with evidence appropriate to the site.
This framework supports scoping and discussion. It does not replace site investigation, engineering assessment or project-specific design.
- 01Define the symptomMap where it occurs, when it was first observed and whether it is stable, intermittent or changing.
- 02Identify plausible mechanismsConsider the structure, ground profile, drainage, loading, construction details, services and operating history.
- 03Test, do not assumeSelect observations and measurements that can distinguish between credible explanations.
Evidence ladder
Build confidence in stages
Observation
Document levels, joints, cracking, rocking, water pathways, local constraints and patterns across the affected area.
Investigation
Use proportionate testing to examine the leading hypotheses. The method and coverage should follow the decision that the evidence must support.
Monitoring
Establish baseline measurements, tolerances, review points and escalation rules before work where ongoing change could affect the decision.
Resource library
Practical guides for early-stage decisions.
Guide 01 · Floors
Voids and rocking slabs
Separate the observed floor response from the possible causes below it, then define the evidence needed before treatment.
Read the guide →Guide 02 · Foundations
Settlement diagnosis
Build a disciplined working hypothesis from movement patterns, site history, drainage, loading and ground information.
Read the guide →Guide 03 · Delivery
Verification planning
Define baselines, acceptance criteria, hold points and records before intervention starts—not after completion.
Read the guide →Guide 04 · Symptoms
Floor and foundation cracks
Document crack patterns and related movement without treating appearance or width alone as a diagnosis.
Read the guide →Guide 05 · Investigation
Selecting investigation methods
Start with the decision and uncertainty, then choose methods capable of testing the leading hypotheses.
Read the guide →Guide 06 · Treatment
Slab lifting versus void filling
Clarify whether the objective is support restoration, level recovery, or both before defining the treatment scope.
Read the guide →Tools in context
What non-destructive investigation can—and cannot—resolve
Methods such as ground-penetrating radar can help identify contrasts and patterns beneath accessible surfaces. Interpretation depends on material properties, site conditions, equipment, survey design and correlation with known features or other evidence.
Outputs should be treated as interpreted evidence rather than a direct picture of every subsurface condition. Where the decision requires greater certainty, intrusive confirmation, survey control or specialist investigation may still be necessary.
Before commissioning a survey, define:
- the decision the survey must inform;
- the target features and expected depth range;
- access, safety and operating constraints;
- known limitations and required corroboration;
- the format, traceability and review standard for results.
Selection discipline
Compare pathways against the same criteria.
- 01SuitabilityDoes the evidence support the proposed mechanism and treatment zone?
- 02ConstraintsCan access, utilities, operations, safety and environmental controls be managed?
- 03VerificationWhat will be measured, when, against which agreed acceptance criteria?
- 04BoundariesWhat is excluded, uncertain or dependent on conditions encountered?
Next step
Turn available evidence into a focused assessment brief.
Prepare the site context, observed condition, records and operating constraints before discussing possible pathways.
Treatment and operations
Compare pathways and control live-site risks.
Guide 07 · Comparison
Resin injection or underpinning?
Compare objectives, structural load paths, disruption, uncertainty and verification before choosing a pathway.
Read the guide →Guide 08 · Operations
Working facilities
Plan investigation and treatment around production, access, hygiene, utilities, safety and shutdown constraints.
Read the guide →Guide 09 · Water
Drainage, washout and settlement
Investigate water pathways and loss of ground together so that visible settlement is not treated in isolation.
Read the guide →Project FAQs
Define the brief, scope and promise clearly.
FAQ 10 · Assessment
What information is needed?
Prepare site context, symptoms, drawings, loads, history, ground information and operating constraints for the first review.
Read the FAQ →FAQ 11 · Scope
How are zones and quantities defined?
Understand why treatment zones are evidence-led and why final quantities can depend on conditions encountered.
Read the FAQ →FAQ 12 · Outcomes
What can be guaranteed?
Separate workmanship, process controls and measurable outcomes from conditions outside the treatment scope.
Read the FAQ →GPR technical resource library
Ground-penetrating radar for ground and slab assessment.
A cornerstone guide plus four focused modules covering survey planning, source-data integrity, processing controls, interpretation confidence, limitations, physical verification and defensible reporting. The complete library is also available in technical Vietnamese.
Evidence hierarchy
- Validate survey geometry and source data.
- Identify repeatable waveform changes.
- Test spatial and processing dependence.
- Compare competing explanations.
- Verify physically where the decision requires it.
Featured ground-improvement resource
Jet grouting: design, execution and verification.
An engineering guide to system selection, ground-model inputs, representative field trials, production controls, spoil and movement risks, QA/QC and objective-specific acceptance evidence.
Delivery sequence
- Define the engineering function.
- Build the project ground model.
- Validate the system through trials.
- Control and record every element.
- Verify geometry and performance.