4.3 Quality Control, Inspections, and Closeout

Quality Control vs. Quality Assurance

• Quality Control (QC) — the contractor's in-process checks that work meets the Contract Documents (e.g., slump tests, torque checks).
• Quality Assurance (QA) — the owner/A/E program that verifies the QC system works (audits, third-party testing).

Exam trap: testing labs hired by the owner perform QA; the GC still owns QC and the means and methods.

Special Inspections (IBC Chapter 17)

IBC Chapter 17 requires Special Inspections for designated work — concrete, masonry, structural steel/welding, high-strength bolting, soils/deep foundations, and fire-resistant materials. The Special Inspector is qualified, approved by the building official, and reports directly to the building official and the A/E, not the contractor. A Statement of Special Inspections is part of the permit set, and a Final Report is required before the Certificate of Occupancy.

Concrete QC numerics

• Slump test — ASTM C143; typical structural slump 3–5 in.
• Compressive cylinders — ASTM C39; standard set broken at 7 and 28 days; f'c acceptance based on 28-day strength.
• Water-cement (w/c) ratio — lower w/c = higher strength/durability; a 0.45 w/c gives higher strength than 0.55.

Worked yield: 1 yd³ concrete = 27 ft³. A slab 40 ft × 30 ft × 4 in (0.333 ft) = 400 ft³ ÷ 27 = 14.8 yd³; order ~16 yd³ (≈8% waste).

Masonry and mortar QC

Mortar types follow ASTM C270 proportions. Higher letter strength = more Portland cement:

Trap: do not use Type O below grade; use Type M or S where soil and water loads act.

Punch List and Substantial Completion

• Substantial Completion — the owner can occupy/use the project for its intended purpose; it starts warranties, transfers risk of loss, and stops most liquidated damages.
• Punch List — the A/E's list of incomplete/defective items finished before final payment.
• Final Completion — all punch items done, closeout documents delivered.

Closeout Documents

Deliver before final payment and Certificate of Occupancy:

1. As-built / record drawings showing field changes
2. O&M (Operation & Maintenance) manuals
3. Warranties and guarantees
4. Affidavit of payment / lien waivers from subs and suppliers
5. Consent of surety to final payment
6. Special Inspection final report and certificates of compliance
7. Attic stock / spare materials and keys

Retainage and final payment

Retainage (commonly 5–10%) is withheld from each progress payment and released at or after substantial/final completion. On a $1,200,000 contract at 10% retainage, $120,000 is held; partial release at substantial completion often reduces it (e.g., to 5%). Final payment generally requires lien waivers and the consent of surety to protect the owner.

QA vs. QC and Special Inspections

Distinguish the pair: Quality Assurance (QA) is the system of procedures that prevents defects (planning, training, audits); Quality Control (QC) is the inspection/testing that detects them (concrete cylinder breaks, weld inspection, density tests). Under IBC Chapter 17, special inspections by an independent agency are required for high-risk work — structural welding, high-strength bolting, concrete, masonry, and soils — with a signed final report of special inspections before the certificate of occupancy.

Punch List, Substantial vs. Final Completion

Near the end, the architect prepares a punch list of items to correct. Substantial completion means the owner can occupy and use the work for its intended purpose; it triggers the start of warranties, transfer of risk/insurance, and release of part of retainage. Final completion follows after the punch list is cleared and all closeout documents are in. Liquidated damages typically stop at substantial, not final, completion.

Closeout Documents

Closeout delivers: as-built (record) drawings, O&M manuals, warranties/guarantees, final lien waivers, affidavit of payment, consent of surety to final payment, and the certificate of occupancy (CO). Retainage is released after final completion and receipt of these. Missing closeout documents are the usual reason final payment is withheld.

Common Exam Traps

• Trap: QA and QC are the same. QA = prevention system; QC = inspection/testing.
• Trap: Warranties start at final completion. They start at substantial completion.
• Trap: The contractor may occupy revenue space at substantial completion — it is the owner who may occupy.
• Trap: A CO can be issued before special inspection final reports are filed.

Testing Agencies, Mock-Ups, and Warranty Periods

An independent testing/inspection agency (engaged by owner under IBC Ch. 17) performs material tests; the contractor must provide access and cure non-conforming work at its cost. For critical assemblies, a mock-up is built and approved as the quality benchmark before full production. Distinguish warranty tiers: the standard one-year correction period (contractor returns to fix defects), longer manufacturer warranties (e.g., 20-year roofing membrane), and any extended/bonded warranties the spec requires. Know who holds and enforces each.

Non-Conformance and Corrective Action

When inspection finds defective work, the QC system issues a Non-Conformance Report (NCR) documenting the deficiency, the spec it violates, and the corrective action. Resolution options are repair, rework, use-as-is (with engineer approval), or reject/replace. The contractor cannot bury a known defect; doing so converts a warranty repair into a fraud exposure. Tracking NCRs to closure before the punch list is part of demonstrating that QA prevented, and QC caught, deviations from the contract documents.