Semiunitized (also referred to as Semi-Unitized or Hybrid Stick-Unitized) glazing is a facade system that combines elements of both stick curtain wall and unitized systems. Individual frames or sub-frames are pre-assembled and glazed in the factory, then transported and stacked onto floor-slab anchors or mullion carriers on site, offering faster erection than stick systems while retaining flexibility for tall or complex buildings.

1.1 Key Characteristics

• Panels are pre-glazed in the factory under controlled conditions
• Lateral load and gravity load transfer to slab brackets or structural steelwork
• Interlocking male/female pressure plates provide weather seals at every joint
• Accommodates building tolerances via slotted/adjustable connections
• Suitable for mid-rise to high-rise commercial, hospitality & residential towers
• Faster installation than stick system; more economical than full unitized

1.2 Typical Panel Configuration

2.1 Design Inputs & Criteria

• Building category, occupancy & height classification
• Wind zone & basic wind speed (IS 875 Part 3 / ASCE 7)
• Seismic zone and inter-storey drift requirements
• Thermal performance — U-value, SHGC, visible light transmittance
• Acoustic performance — Rw rating targets (dB)
• Floor-to-floor height, slab edge condition and structural grid
• Facade articulation — setbacks, reveals, projections
• Fire compartmentalization & spandrel height requirements

2.2 Structural Design

Semiunitized panels must be engineered for wind pressure (positive & negative), dead load (self-weight) and live loads (maintenance access). Key structural checks include:

• Frame section modulus & moment of inertia for spans up to 4500 mm
• Deflection limits: L/175 for glass edges; L/200 for panel overall
• Glass thickness design per EN 13474 or ASTM E1300 (4-side / 2-side supported)
• Bracket capacity and weld/bolt group calculations
• Differential movement — thermal expansion Δ = α × L × ΔT; min. 10 mm movement joint
• Wind-on-glass: design pressure Cp = ±1.3 for corner zones

2.3 Thermal & Energy Design

• Low-E coating on Glass Position 2 (outer surface of inner pane for DGU)
• SHGC calculation per ISO 9050 / ASHRAE 90.1 compliance check
• Condensation risk analysis on frame/glass inner surface

2.4 Acoustic Design

• Selection of glass build-up (e.g., 6+12A+6 DGU vs. 6.4 PVB+12A+6 laminated)
• EPDM/neoprene acoustic gaskets at perimeter joints
• Acoustic test (Rw, Ctr) per ISO 140-3 / ASTM E90 from accredited lab

2.5 Drawings & Documentation

• Architectural Facade Elevation & Section Drawings (Scale 1:50 / 1:20)
• Shop Drawings — Typical & atypical panels, connections (Scale 1:5 / 1:2)
• Fabrication Drawings — cut lists, drilling patterns, notching
• Structural Calculation Report (stamped by Professional Engineer)
• Energy Performance Report
• BIM Model (LOD 400) — clash detection with structure and MEP

3.1 Scope of Estimate

• Supply and installation of semiunitized facade panels
• Anchor/bracket system and structural steelwork
• Glass units — primary, spandrel, vision areas
• Joint sealing (silicone, fire-rated sealant at spandrel)
• Shop drawings, engineering, testing & certification
• Temporary protection, cleaning and commissioning

3.2 Quantity Takeoff Parameters

3.3 Pricing Components

• Material cost — extrusion, glass, hardware, consumables
• Fabrication cost — cutting, machining, glazing, QC, packaging
• Engineering & shop drawings — typically 1.5–2.5% of contract value
• Third-party testing (lab + site) — budgeted as lump sum per specification
• Logistics — factory to site, crane hire, storage
• Installation labour — scaffold or gondola, equipment
• Overheads, profit margin and contingency (10–15%)
• Statutory approvals, insurance and bonds

3.4 Estimation Checklist

• Obtain approved architectural drawings and specifications
• Identify all panel types (typical, corner, curved, spandrel, vented)
• Quantify each panel type separately with elevations
• Obtain structural slab survey report for tolerance assessment
• Request glass mock-up and lab test budget from glazing supplier
• Check import duties on aluminium extrusions if imported
• Confirm local labour norms (installation rate m²/man-day)

A precise site survey ensures the fabricated panels will fit the as-built structure and that the anchor bracket design accounts for real-world deviations from the architectural grid.

4.2 Survey Instruments

• Total Station (accuracy ±2 mm at 50 m) for primary grid and floor levels
• 3D Laser Scanner (point cloud, ±3 mm) for complex geometry
• Spirit Level and plumb bob for local checks
• Digital Vernier Caliper for embed plate dimensions
• Pull-out tester for anchor verification in concrete

4.3 Survey Parameters

4.4 Survey Process

1. Establish a primary datum and control grid at each floor level
2. Survey all slab edges, columns and embed plates floor by floor
3. Record deviations in a tabulated survey report with AutoCAD overlays
4. Issue survey report to design team for bracket adjustment
5. Obtain structural clearance before commencing fabrication
6. Conduct a final pre-installation check survey before panel delivery

4.5 Survey Documentation

• As-built survey report (per floor, per grid), signed by licensed surveyor
• Deviation map — colour-coded AutoCAD floor plans
• Photographic record of slab edge, embed conditions
• Anchor pull-out test certificates for cast-in or chemical anchors

5.1 Factory Setup Requirements

• Clean, covered fabrication bay with controlled temperature (15–35°C)
• Assembly tables with precision surface flatness ≤ 2 mm over 3 m
• CNC machining centres for drilling, routing, notching
• Dedicated structural glazing bay with downdraft ventilation for silicone application
• Glass storage — vertical A-frames with felt padding, minimum 200 mm clearance

5.2 Fabrication Sequence

1. Receive and verify aluminium extrusion to shop drawing cut list
2. Cutting to length — double mitre or square cut per frame detail
3. CNC drilling, routing, notch and hole punching
4. De-burring and surface cleaning; anodising or powder coating (if applicable)
5. Thermal break strip insertion and roll-crimping (PA66 GF25)
6. Frame assembly — corner keys, splice bars, end caps
7. Weatherstrip / EPDM gasket insertion into extrusion grooves
8. Structural silicone application for structural glazing (if SSG type)
9. Glass insertion and mechanical capping or pressure plate fixing
10. Final QC inspection per panel — visual, dimension, torque check
11. Panel numbering, wrapping and loading for dispatch

5.3 Quality Control in Fabrication

5.4 Mock-up Panel

Prior to full production, a full-size mock-up panel shall be fabricated and subjected to lab testing (Section 8). Only upon satisfactory test results shall production commence. All production panels shall replicate the approved mock-up exactly in terms of materials, section profiles, fixing details and sealant specifications.

6.1 Pre-Installation Requirements

• Structural works complete and cleared — concrete cure ≥ 28 days
• Embed plates / cast-in channels surveyed and accepted
• Safe working platform — scaffold, gondola or mast climber
• Crane or material hoist for panel lifting
• Rigging plan and lift study approved by site safety officer
• All panels inspected on delivery; damaged panels rejected and replaced

6.2 Installation Sequence

1. Set-out primary installation gridlines at every floor using total station
2. Install slab brackets / anchor cleats per approved bracket schedule
3. Fix lower transom carrier or sill track at base of each floor
4. Hoist and set first panel — align to grid; adjust 3-axis via slotted holes
5. Install interlock / stack joint cover strip at horizontal joint
6. Hoist and set subsequent panels on same floor — align horizontally
7. Fix pressure plates / capping strips; torque to specified value
8. Apply wet silicone to vertical movement joints between panels
9. Progress floor by floor; check plumb and level after each floor
10. Install any fire-stop mineral wool + intumescent at spandrel zone
11. Install operable vent sashes and hardware
12. Final alignment check — string line, spirit level, total station
13. Remove temporary protection film from glass and frame

6.3 Handling & Lifting

• Vacuum lifters or purpose-made panel clamps — capacity ≥ 2× panel weight
• No bare metal contact with glass or anodised/powder-coated frames
• Panels stored vertically on padded A-frames on site; max 10° from vertical
• Do not stack panels horizontally
• Wind speed limit for panel installation: maximum 40 km/h

6.4 Sealant Application at Joints

• Joint surfaces cleaned with isopropanol wipe — allow 15 min before sealing
• Apply bond-breaker tape at joint back; prime substrate per sealant manufacturer
• Tool joint to concave profile; width : depth ratio = 2:1 minimum
• No sealant application below 5°C or above 40°C ambient
• Curing period: 21 days before water testing (weather permitting)

6.5 Protection During Construction

• Maintain factory-applied polyethylene protection film until handover cleaning
• Remove within 60 days of installation to prevent adhesive bonding to surface
• Cover exposed glass during concrete or plaster pours above
• Tag and track any cracked glass discovered during installation for replacement

7.1 Pre-Handover Checklist

• 100% visual inspection of all panels — glass, frame, sealant, hardware
• Water test completed (floor-by-floor) and passed — test certificates available
• All operable vents/doors operate freely with correct hardware adjustment
• Protection film removed; facade cleaned with approved detergent
• All temporary brackets, clips, wedges and aids removed
• Touch-up of minor finish damages with approved touch-up paint/anodising pen
• Snag list raised and closed — sign-off by client or main contractor's QA

7.2 Handover Documentation Package

7.3 Maintenance Schedule

A comprehensive warranty programme for semiunitized glazing covers the performance of individual components as well as the integrated installed facade system. Warranties must be backed by the original manufacturers and the facade contractor respectively.

8.2 Warranty Matrix — By Product

8.3 Warranty Activation Requirements

1. All materials must be sourced from approved manufacturers and verified by Mill Test Certificates (MTC)
2. Silicone sealant adhesion tests (7-day and 21-day peel) must pass and be documented
3. Lab mock-up test report must be submitted and approved before production
4. Installation must be carried out by trained and certified applicators for structural silicone
5. Site water test must be completed and passed before handover
6. O&M manual must be received and acknowledged by building owner/FM team

8.4 Warranty Claim Process

All laboratory tests are conducted on full-size mock-up assemblies representing the most critical panel configuration. Tests are performed at an internationally accredited facility (NABL / UKAS / A2LA) before production release.

9.1 Sequence of Tests (ASTM Standards)

9.2 Additional Material Tests

9.3 Test Failure Protocol

• Identify root cause — design deficiency, material non-conformance or workmanship error
• Issue NCR (Non-Conformance Report); implement corrective action
• Rectify mock-up and re-test the failed sequence only
• Maximum two re-test attempts; persistent failure triggers design review

Site water testing verifies the installed facade's watertightness under simulated wind-driven rain conditions. It is performed after panel installation and sealant cure, but before protection film removal and handover. Testing shall be progressive — floor by floor — with results recorded and signed off by the client's representative.

10.2 Test Methods

10.3 Testing Parameters & Acceptance Criteria

10.4 Testing Protocol

1. Identify all joint types: vertical movement joints, horizontal stack joints, corner joints, window-door perimeters
2. Seal internal areas with polythene sheeting to detect and trace any ingress precisely
3. Apply test pressure / hose — start from bottom of facade, work upward
4. Observer inside building monitors for any water ingress at joints, frame intersections and fastener locations
5. Any ingress found: stop test, mark location, record on floor sketch
6. Investigate and rectify — additional silicone, gasket replacement, or bracket adjustment as needed
7. Re-test rectified areas after minimum 48-hour cure
8. Issue test certificate per floor — signed by facade contractor QA and client representative

10.5 Common Failure Locations & Remedies

10.6 Test Records to be Maintained

• Water test register: date, floor, zone, method, pressure applied, result, witness signatures
• Photographic log: before, during and after each test zone
• Leak sketch plan: exact location of any ingress marked on floor plan
• Remediation record: repair method, sealant batch number, re-test result
• Final test certificate per floor: issued only when all areas pass without active leaks

11.1 Process Summary

11.2 Key Standards Referenced