Understand how Quality Control and Monitoring in Construction Process

Quality control (QC) and monitoring guarantee that the end product corresponds to the drawings and specifications, follows the codes, and meets customer expectations. The impact of poor quality leads to rework, delays, extra costs, safety problems, and controversial situations. The process of good quality management starts from day one and is managed through the entire process until handover.

This article looks at the ideas and the methods and the practices concerning monitoring of quality at different stages.

Quality Planning (QP)

Formulating rules, methods, duties, and means prior to the commencement of work

Quality Assurance (QA)

Preemptive measures aimed at giving an assurance that requirements will be fulfilled (methods/audits/courses)

Quality Control (QC)

Testing work and materials to uncover defects

Monitoring

Consistent observation of progress, quality, cost, and safety versus the plan

Corrective action

Correction of the detected defect and its root cause

Preventive action

Revision of the procedures in such a way that the anomaly does not appear again

The Quality Management Cycle (PDCA)

1. Plan: set quality objectives, standards, and inspection points.

2. Do: execute the work using approved methods and materials.

3. Check: inspect, test, measure, and audit.

4. Act: correct defects, update procedures, and improve.

This cycle repeats for every activity, such as excavation, reinforcement, concreting, and masonry.

Stage 1: Quality Planning (Pre-Construction)

Documents prepared

• Project Quality Plan (PQP): the master document defining the quality system, roles, standards, and procedures

• Inspection and Test Plan (ITP): lists each activity, what is checked, the method, the acceptance criteria, the frequency, and who inspects or approves

• Method statements: step-by-step procedures for key activities

• Material approval submittals: samples, test certificates, and data sheets

• Quality checklists for each activity

• Quality organization chart: QA/QC manager, engineers, inspectors, and their authority

Hold point Work should not proceed until the approval is received from inspector or client (for example, prior to laying concrete).

Witness point Should the client or consultant be informed, it is noted as a witness point but work may continue if the client does not attend.

Review point The documents are looked at.

Surveillance Occasional checks.

Standards and codes
The applicable codes (for example IS codes, ASTM, BS, or Eurocodes) and project specifications are listed so that acceptance limits are clear.

Stage 2: Material Quality Control

Materials are checked before they reach the work.

Approval and receiving

• Source approval and sample testing

• Manufacturer test certificates

• Inspection on delivery: quantity, condition, brand, grade, batch, and expiry

• Rejected material is tagged and removed from site

• Proper storage: cement off the ground and dry, steel protected from rust, aggregates separated

Typical tests

Stage 3: Quality Control of Construction Activities

Survey and layout

• Verify benchmark, grid lines, and levels

• Check diagonals, offsets, and setbacks

• Record and approve before excavation

Earthwork and excavation

• Check dimensions, depth, and bottom level

• Verify founding stratum against the geotechnical report

• Compaction testing: Proctor and field density (commonly 95 to 98 percent)

• Dewatering and slope or shoring checks

Foundation and concrete work

Before concreting (hold point checks)

• Excavation level and cleanliness, and the PCC layer

• Reinforcement: bar diameter, spacing, laps, cover blocks, anchorage, bending shapes

• Formwork: alignment, dimensions, rigidity, tightness, oiling or release agent

• Embedded items: sleeves, conduits, inserts

• Concrete pour card approval

During concreting

• Verify the concrete mix design and delivery ticket

• Slump or flow test on each truck or batch

• Temperature measurement in hot or cold weather

• Cube sampling: commonly a set of cubes for each batch volume per code, tested at 7 and 28 days

• Check placement, compaction (vibrators), height of drop, and segregation

• Maintain pour records: time, volume, location, and weather

After concreting

• Curing: wet curing, ponding, curing compound, or wrapping for the specified period (commonly at least 7 days for ordinary cement)

• Formwork removal only after the minimum strike period or strength

• Visual inspection for honeycombing, cracks, and surface defects

• Non-destructive testing where needed: rebound hammer, ultrasonic pulse velocity, core tests

• Acceptance based on cube results and code criteria

Reinforcement and steel structures

• Welding inspection, bolt torque, and joint checks

• Non-destructive testing of welds: dye penetrant, magnetic particle, ultrasonic, or radiography

• Paint and corrosion protection thickness

• Alignment and verticality checks (plumb and level) during erection

Masonry and plastering

• Block or brick grade, mortar mix, and joint thickness

• Alignment, plumb, level, and bonding with columns

• Curing of masonry and plaster

• Plaster thickness, flatness (straight-edge test), and absence of hollow sounds

Waterproofing

• Surface preparation and primer

• Membrane thickness, overlaps, and detailing at corners and drains

• Flood or ponding test (commonly 24 to 72 hours) before covering with screed or tiles

MEP works

• Electrical: conduit routing, wire sizing, insulation resistance (megger) test, earth resistance test, circuit continuity, and load testing

• Plumbing: hydrostatic or pressure test of supply lines, leak tests, drain slope, and flow tests

• HVAC: duct leakage test, air balancing, and equipment commissioning

• Fire systems: sprinkler hydro test, alarm system function test, and hydrant flow test

Finishing works

• Flooring: level, slope, hollow sound test, joint alignment, and shade matching

• Painting: surface preparation, number of coats, coverage, and uniformity

• Doors, windows, and joinery: alignment, operation, sealing, and hardware

• Mock-up approvals for facades, toilets, and typical rooms before bulk work

Stage 4: Inspection Process Flow

A typical workflow for each activity:

1. Contractor completes the activity and the site engineer self-inspects using a checklist.

2. Request for Inspection (RFI) is raised to the consultant or client.

3. Inspection is carried out against drawings, specifications, and the ITP.

4. Outcome:

   • Approved: work proceeds

   • Approved with comments: minor items fixed without a stop

   • Rejected: rectify and re-inspect

5. Records are signed and filed.

Stage 5: Non-Conformance Management

When work or material does not meet requirements:

1. Identify and record the issue in a Non-Conformance Report (NCR), with location, description, photos, and the clause breached.

2. Contain the problem by stopping related work and isolating suspect material.

3. Root cause analysis: methods such as the 5 Whys or a fishbone (Ishikawa) diagram.

4. Decide disposition: accept as is (with engineer approval), repair, rework, or reject and replace.

5. Corrective and preventive actions are implemented.

6. Verification and closure by the QC or consultant.

7. Track NCRs in a register, and review trends monthly.

Stage 6: Monitoring Progress, Quality, and Performance

Monitoring is the control side of project management. It compares actual performance against the plan and triggers action.

What is monitored

Monitoring tools

• Daily and weekly progress reports with photographs

• Site diaries recording weather, labor, equipment, and events

• Weekly coordination and monthly review meetings

• Planning software such as Primavera P6 or MS Project

• BIM and 4D/5D models linking schedule and cost to the model

• Project management platforms such as Procore or similar systems for RFIs, snag lists, and approvals

• Site technology: drones for progress surveys, laser scanning to check as-built geometry, and IoT sensors for concrete temperature and maturity

• Earned Value Management (EVM): compares planned value, earned value, and actual cost to measure schedule and cost performance (SPI and CPI)

Key performance indicators (KPIs)

• Schedule Performance Index (SPI) = Earned Value / Planned Value

• Cost Performance Index (CPI) = Earned Value / Actual Cost

• Rework cost as a percentage of the contract value

• First-time pass rate of inspections

• NCR closure time

• Number of open snags at handover

An SPI or CPI below 1 signals trouble and calls for corrective action.

Stage 7: Audits and Reviews

• Internal quality audits check that site practice follows the quality plan

• Third-party and client audits provide independent assurance

• Supplier and subcontractor audits

• Management reviews examine trends and decide on improvements

Findings are logged, assigned, and closed with evidence.

Stage 8: Testing, Commissioning, and Handover Quality

• Individual system testing, followed by integrated system testing

• Commissioning with witnessed performance tests

• Snagging: detailed walk-through to build a defect list, followed by rectification and re-inspection

• Documentation handover:

  • As-built drawings

  • Test certificates and inspection records

  • Material approvals and warranties

  • O&M manuals

  • NCR closure records

• Completion certification from authorities

Stage 9: Post-Handover

• Defects liability period (commonly 6 to 12 months), with tracking of defect reports and response times

• Warranty claims management

• Post-occupancy feedback

• Lessons learned review fed into the next project's quality plan

Documentation and Records

Quality is only provable with records. Keep:

• Inspection and test plans and completed checklists

• Material test reports and approvals

• Concrete pour records and cube results

• Survey and level records

• NCR register and closure reports

• Calibration certificates for testing and measuring equipment

• Photographs, with date and location

• Meeting minutes and correspondence

Good records protect all parties in disputes and warranty claims.

Roles and Responsibilities

Common Quality Problems and Prevention