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16265 Construction Technology 2

Week 1

Regulatory Implementation and Construction Concepts 

• Local Government (LG) 

  • Sets land use zoning (residential, industrial, commercial)

  • Controls: building size, setbacks, overshadowing, stormwater 

  • Powers under the Environmental Planning and Assessment Act

• National Construction Code (NCC):

  • Mandatory building regulation (10 building classes) 

  • LG administers; focus - performance outcomes 

  • Focus: Volume 1

• Principal Certifying Authorities (PCAs):

  • Health & Amenity: weatherproofing, noise, light, ventilation 

  • Safety: fire, egress, structural integrity, services 

  • Sustainability: energy + water 

  • Compliance 

Principal Certifying Authorities (PCA)

• LG or accredited certifier 

• Issue construction/compliance certificates 

• Ensure NCC + local compliance 

• Inspect at critical stages 

NCC & Reference Documents 

• Australian Standards: only mandatory  when NCC referenced them 

• Provide descriptive details (materials, processes) 

• Best practice ≠ DTS (demand to satisfy) (higher quality, costlier) 

  • F2P2: prevent water penetration (behind fittings, into cavities) 

  • F2D2: gives BTS methods to comply 

Multi-Residential Concepts

• Strata ownership: group land + structure, private units 

• Compartmentalisation: fire/noise separation via party walls/floors 

• SOU: sole occupancy unit 

• Types: 

  • Townhouses/row houses → 2 storey, common walls, state-titled 

  • Apartments → multi-storey, shared fire egress + carparks (main focus) 

Site Establishment & Materials Handling

• Aim: efficient + safe material movement

• Storage: compounds, sheds, basements, floor areas

• Tall buildings → loading platforms essential 

• Plan crane/truck/pump circulation 

• Problems 

  • Limited space 

  • Delivery vs crane coordination 

  • Prefer just-in-time delivery 

  • Need cranes/hoists 

Cranes

Week 2

Machine Type/Selection 

Detailed Excavation 

• Elements excavated: pad footings, piers, pile caps, strip footings, stormwater/services, crane & joist foundations

Dewatering 

• Water Table = soil saturated by groundwater.

• Needed to stabilise soil → prevent collapse.

• Methods:

  • Well Points → small tubes + vacuum pump; used in silts/sands; effective to ~6m depth

  • Wells → borehole with submersible pump; for more permeable soils

  • Horizontal Drainage → trenches with perforated pipe + pump (for surface water)

Remediation 

• Consultant testing → classify material

• Contaminated soil removed, leaving VENM only (under geotech supervision)

Removal & Disposal

• Cartage of soil via bogies or trucks & dogs 

• Truck type depends on disposal option + site conditions 

Shoring and Piling 

• Shoring: supports/retains soil to prevent collapse (temporary) 

• Piling: supports footings or forms retaining walls (e.g., diaphragm walls)

Reinforced concrete piles with shotcrete infill 

• Alternative to blockwork basements

• Cost: ~$800/m² (vs $500/m² for shoring) but provides permanent retaining wall

• Process (before bulk excavation):

  • Drill pile holes

  • Place reinforcing

  • Pour concrete (piles extend below floor for cantilevering)

  • Shotcrete infill wall between piles

Week 3

Concrete Properties 

• Durability: hardens with age 

• Shrinks slightly 

• Small dimensional variation (not fired) 

• Appearance: plain but uniform 

Masonry

• Advantages: flexible small units, easy to construct 

• Blocks (hollow): strong when reinforced; weak unreinforced, esp. Under horizontal loads 

Reinforcing Steel 

Codes:

• “N” = normal ductility

• Deformed bars (ribs) = main reinforcing, 500MPa

• Round bars “R” (smooth) = ligatures, cages, 250MPa

  • Example: N16-400 → 16mm diameter, 400mm spacing

• Other terms:

• Splice = overlap between bars

• Cogs/hooks = bends for anchorage & load transfer

Recycling in Masonry 

• Blocks up to 30% lighter 

• Aggregate replaced with bottom ash (coal furnaces) + slag sands (steel by-product)

• Cement partly replace with slagment (steel furnace paste) 

• Reduces use of natural river aggregates and sands 

Mortar Joints

• Functions: bedding, load transfer, bond strength 

• Requirements: 

  • Accurate batching 

  • Washed sands (avoid brickies mix → shrinkage) 

  • Hollow blocks laid with face shell bedding (no web mortar)

• Joint Finishes:

Grouting Cores 

• Methods: hand hoppers of pump nozzle 

• Preparation: clean cores, provide clean-out openings, cool with water in hot weather 

• Pouring rules: <3m per lift, 30 min apart if >2.4m 

• Specs: 

  • Strength: min 12MPa (prefer 20MPa) 

  • Cement: >300kg/m³

  • Aggregate: 10mm coarse gravel 

  • Consistency: flowable, surrounds reinforcement fully 

Control Joints 

• Purpose: prevent cracks from shrinkage, thermal movement, footing settlement, hogging/sagging

• Locations: changes in wall height/thickness, junctions, door/roof slabs, straight walls (special blocks available) 

Gravity Wall Systems 

• Features: free draining, flexible, cost effective, suits most soils 

• Can be upgraded with soil reinforcement for taller/stronger walls 

• Construction process: 

  • 1. Place aggregate leveling pad 

  • 2. Lay blocks with reinforcement + backfill 

Week 4 

Context

• Basements are common in multi-unit residential buildings for underground parking 

• Typically constructed with concrete block walls and poured in-situ concrete columns on strip and pad footings 

• The suspended ground floor slab acts as a diaphragm, resisting horizontal forces on basement walls from ground and hydrostatic pressure 

Pier and Pile Cap 

• Distributes load from the concrete block pier to the bored on-ground pile 

Strip Footings 

• Support engaged blade columns on the perimeter wall 

• Constructed with reinforced, core-filled concrete blocks 

• Include infill-slab, column, and isolation joint 

Blockwork Detail 

• Reinforced, core-filled concrete block construction 

• Strip footing supports the wall 

• Wet wall and retaining wall required 

• Clear load path from wall → strip footing 

• Isolation joint separates infill slab from main structure 

  • Used for infill/on-grade slabs 

  • Separates concrete slab from adjoining structures to prevent restraint 

  • Allows vertical and horizontal movement due to time or temperature changes 

  • Filled with compressible cellular materials 

Basement Walls - Strength and Waterproofing 

• Must ensure structural integrity and waterproofing 

• Hydrostatic pressure from groundwater creates high loads and potential leakage 

• Similar to an in-ground pool in reverse (water outside pressing inward) 

Early Decisions on Hydrostatic Load 

• Wet wall construction - soil is tight against wall; must resist moisture pressure 

• Separate retaining wall - built outside the main building; takes the hydrostatic load, protecting the basement wall 

General Issues 

• Wet walls require: 

  • Waterproofing, sub-soil drainage, structural design 

  • Goal: drain or shed groundwater to reduce hydrostatic pressure 

  • On sloped sites, the building may act as a dam to upstream water 

  • Civil and hydraulic engineers assist with drainage design 

Three Fundamentals of Wet Wall Systems 

• Structural Adequacy: resist hydrostatic pressure, earth pressure, and superimposed loads

• Relieve Hyostatic Pressure: ensure drainage paths and load relief

• Waterproofing: continuous, impervious membrane or drainage system to divert water 

Selecting Wet Wall Retaining Systems 

• Based on cost vs performance & durability (No NCC requirement for durability)

• Consider: 

  • NCC performance requirements 

  • Amount of water expected on site 

  • Water table height & variability 

  • Use of basement: 

    • Habitable: must be fully waterproofed 

    • Non-inhabitable: minimal waterproofing acceptable 

Site Factors 

• Rainwater run-off and drainage capacity 

• Soil type: sand drains better than clay 

• Water table height vs basement depth 

Habitable vs Non-Habitable Spaces 

Paint-On Liquid Membranes 

• Requires careful application (avoid thin or missed areas) 

• Used for low-risk areas: 

  • Low-risk basements, balconies, planter boxes, retaining walls, water tanks 

Self-Adhesive Sheet Membranes 

• More consistent than paint-on-types 

• No heating required 

• Uniform thickness ensures quality 

• Used for mid to high-performance: basements, retaining walls, ramps 

High Performance (Risk Level 1) – Sealed/Tanking Systems 

• For high-risk conditions (constant hydrostatic pressure) 

• Features: 

  • Thicker, robust membranes (resist pinholes)

  • Continuous “skin” around entire structure 

  • Enhanced detailing at joints and wall-floor junction 

  • Protection from sulphates in groundwater 

  • Comprehensive sub-soil drainage 

    • Drainage layer under floor slab 

    • Multiple agricultural drains 

    • Drainage cells/logs + geotextiles (prevent clogging) n

    • Protective layers (fibre cement, foam, screed) 

Torch-On Membranes 

• Typical for high-performance applications (tanking systems) 

• Best option but required skilled installation to heat-weld seams 

• Must include protection from damage and ensure adequate drainage 

• Used for: 

  • High-performance basements, lift pits, car parks, roofs, landscaped/green roofs

Week 5 

Introduction

• In multi-residential buildings, sound insulation often governs the choice of construction system more than fire resistance 

• Sound: everyday comfort issue 

• Fire: protection against extreme events 

• Goal: economically satisfy both fire and acoustic performance within a single construction solution 

Steps in Choosing a Construction System (NCC Framework) 

1. Define NCC Building Classification & Compliance Pathway 

• Determine the class of building (e.g. Class 2 apartments) 

• Identify the basis for compliance (Deemed-to-Satisfy, Performance Solution, etc) 

• Establish the arrangement of Sole Occupancy Units (SOUs)

2. Sole Occupancy Units (SOU) 

• Arrangement of SOUs affect both fire and sound performance 

• Walls, floors and ceilings are critical 

• SOU Configurations 

  • Side-by-side units → wall performance important 

  • Stacked vertically → floor/ceiling performance important 

  • Adjoining other spaces (corridor, stair, etc) → fire & acoustic separation required 

• Note: even internal SOU walls/floors may need fire-rating if they support fire-rated elements above 

3. Define Sound Performance Requirements 

• Governed by NCC Vol 1 - Section F, Part F7 (Sound Transmission and Insulation) 

• Performance Requirements F7P1: controls sound transmission through walls, floors, and ceilings between SOUs

• Deemed-to-Satisfy Provisions

  • Specify minimum sound insulation values (Rw + Ctr) for separating elements 

  • Key Steps: 

    • Identify which walls/floors bound SOUs 

    • Understand sound measurement and rating terms 

    • Select a system that meets or exceeds NCC minimum requirements 

4. Sound Insulation Strategies 

• Add Mass: heavier elements (concrete, masonry) block sound 

• Isolate sides: use double-stuf or cavity wall construction 

• Absorb sound: fill cavities with mineral wool or similar material 

• Seal penetrations: close gaps around services with acoustic sealant or expanding foam 

• For Windows and Doors

  • Weak points for noise leakage 

  • Use: 

    • Thicker or double glazing 

    • Acoustic sealant between wall and frame 

    • Gaskets around openable parts 

    • Solid-core doors for better sound resistance 

5. Define Fire Performance Requirements 

• Main Objectives 

  • Safeguard occupants during fire events 

  • Enable safe evacuation 

  • Facilitate emergency services access 

  • Prevent fire spread between buildings 

  • Protect the building from structural failure

6. Determine Fire Resistance Requirements 

• NCC Type of Construction (C2) 

  • Type A – Highest protection:

    • Structure must withstand full burnout 

  • Type B – Moderate protection: 

    • Partial structural protection 

  • Type C – Lowest protection 

    • Basic separation only (typically Class 1-2) 

    • Some concessions apply (eg sprinklers) 

7. Fire Resistance Level (FRL) 

• Expressed as structural adequacy / integrity / insulation (in minutes) 

• Eg.

  • 60 / 60 / 60 → all 3 properties required for 60min 

  • – / 60 / – → only integrity needed for 60 min 

  • Structural adequacy: element can carry load 

  • Integrity: stops flames/smoke/gases 

  • Insulation: limits temperature rise on the unexposed side

8. Other Fire Considerations 

• Non-combustible materials often required for external walls (Type A & B) 

• Smoke-proof walls for large buildings or long corridors 

• Roof ceilings resistance against early fire spread 

• Shafts (lifts, garbage chutes, services) need special detailing 

• Fire isolated stairs for evacuation routes 

9. Merging Sound and Fire Requirements 

• Final System must meet both performance criteria 

• Typically achieved by selecting tested manufacturer systems that: 

  • Are NCC-Compliant 

  • Have certificated for FRL and acoustic ratings (Rw + Ctr) 

• Manufacturers provide detailed tested system data to ensure compliance 

Week 6 

Introduction 

• Most common floor systems in multi-unit residential buildings

• Advantages: good noise/fire insulation, thermal mass, high strength, termite resistance, widely available, cost-effective 

• Disadvantages: labour-intensive (formwork), slower than prefab systems 

• Concrete: strong in compression, weak in tension/shear → steel added to resist tension 

Load Behaviour 

• One-way Slab 

  • Spans in one direction between walls 

  • Bottom steel resists tension; top steel for shrinkage/temperature 

• Two-way slabs 

  • Spans in two directions (nearly square panels) 

  • Bottom steel both ways (shorter span first); top steel for shrinkage control 

Reinforcing Types 

• Simple span

  • Between to support; tension at bottom → steel at slab base 

• Continuous span 

  • Over multiple supports; reverse bending at supports → extra top steel 

• Cantilever 

  • Overhangs support; tension at top → reinforcement at top face 

Shrinkage & Temperature Steel 

• mesh/fabric on top of slab 

• Controls cracks from shrinkage and thermal movement 

• More steel needed for long slabs 

Punching Shear (at Columns) 

• Localised failure where column pushes through slab 

• Prevented with extra reinforcement, drop panels, or shear heads 

Week 7

Brick Materials 

• Clay bricks - fired in kilns, expand after firing (‘E’ = expansion coefficient) 

  • Expansion joints every 6-12m to prevent cracking 

• Concrete bricks - moulded, steam-cured; shrink slowly as they dry 

• Calcium-silicate bricks - low-strength, porous, mostly obsolete 

• Avoid mixing clay (expanding) and concrete (shrinking) in one wall 

Sustainability Implications

• Old brick firing: charcoal/coal → pollution 

• Modern bricks: gas or electric kilns → cleaner but every-intensive 

• Concrete bricks use cement (high embodied energy) 

• Both brick types have high embodied energy but long life → reuseable/recyclable 

Damp Proof Course (DPC)

• Stops rising damp and salt attack 

• Common: polyethylene; tougher: bitumen-coated aluminium 

• Install 150mm above ground, allow sight wall projection 

Cavity Walls 

• Two skins: of brick with an air gap and wall ties 

• Outer skin: weather protection, aesthetics 

• Inner skin: load-bearing, often rendered 

• Cavity: prevent moisture transfer, adds insulation 

• Limit height to one storey; ensure flashings, weep holes, clean cavity 

• Avoid using conduits/pipes in cavity 

Flashings

• Prevent water entry around windows, doors, roofs, chimneys 

• Must drain to outer wall through weep holes 

• Fragile - inspect before covering; longer laps = better performance 

Brick and Mortar Properties 

• Durability: exposure grade for marine zones; general purpose elsewhere 

• Absorption lower = better resistance to damp 

• Expansion: up to 2mm/m; allow joints for growth 

• Mortar: 

  • Use GP/GB cement, clean sand/water 

  • Lime improves workability 

  • Avoid dishwashing liquid or excess additives 

• Mortar Classes (C:L:S)

Wall Ties 

• Tie skins together; resist tension/compression; stop water bridging 

• Spacing: 600mm centres (300mm near openings) 

• Embodiment: 50mm min 

• Classes: light → heavy; R1 - R5 for durability 

Movement Joints 

• Expansion / control joints: handle brick growth + thermal change 

  • Typically 10mm gaps with foam and mastic

• Slip joints: between brick walls & concrete slabs to allow horizontal movement 

• Articulation joints: isolate wall panels to manage footing movement - often near corners, doors, windows 

Lintels 

• Support masonry above openings 

• Engage ≥ 50mm each side (100mm for large spans) 

• Prop until mortar cures 

• Flat bar = non-load bearing; angle bar = bearing 

Brickwork Practice 

• Set-out: maintain bond (overlap pattern) & gauge (course height) 

• Bond: eg stretcher bond, ~230mm brick + 10mm joint 

• Gauge: ~86mm per course (brick + joint) 

• Trowel work: butter ends (“perpends”), keep plumb & level 

• Scaffolding: adds cost/time - use efficiently 

• Labour rates: 1 bricklayer ~ 750 bricks/day (ideal) 

Handling & Delivery 

• Delivered on pallets or slings, unloaded by crane 

• Distribute to sun-stacks near work area 

• Keep materials consistent (same sand/cement batches) 

Week 8 

Cross Laminated Timber (CLT)

• Large solid timber panels (e.g., 12 m × 2.4 m × 180 mm)

• Made of wide planks (≈ 250 mm) glued in alternating layers (cross-laminated)

• Used for walls, floors, and roofs in mid-rise timber buildings

Panelisation & Installation Process

• 3D model → reverse-engineered to individual panels (panelisation)

• Panels cut by CNC machine → labelled and sequenced for install

• Delivered just-in-time for crane lifting and install

• Wall-to-floor joints: brackets; wall-to-wall: long self-drilling screws

• Floors pulled tight using clamps

Screed Over CLT Floors 

• Used to improve acoustic performance 

• Material: gypsum/polymer concrete; 30-50mm thick. 30-40kg/m²

• Pumped self-levelling screed preferred 

• Adds weight-affects floor and stud design

Next Generation: Post & Plate Construction

• Ideal for 4–8 storey buildings (residential, commercial, institutional)

• No beams → cleaner ceiling; free underfloor service space

• Posts can be exposed (offices) or hidden (apartments)

• CLT floor plate thickness governs span

• Steel shear plate/post head = key connection

• Focus: “Design for Manufacturing & Assembly (DfMA)”

• Work breakdown: 35% waste, 45% indirect, 20% direct

Week 9 

NCC Requirement

• FP 1.4 Weatherproofing: Roofs/external walls must prevent water that causes unhealthy, dangerous or damp conditions

• Exemptions: Classes 7–8 (no need), garages, sheds, open stands, open-deck carparks

• Biggest failure cause: Inadequate pitch/fall.
  
  

NCC DTS Roof Coverings (F1.5)

• Concrete or terracotta tiles, fibre-cement, metal, or plastic sheet roofing—all per relevant AS standards

NCC on balcony and terrace waterproofing DTS: 

KEY DESIGN POINTS

• General Issues 

  • Waterproofing = high risk trade → small defects = leaks

  • Falls: 1 : 100 min, 1 : 60 better

  • Flat roofs / balconies act like shallow pools; outlets crucial

  • Penetrations (vents, balustrades) are weak points

  • Deemed-to-Satisfy standards for external above-ground membranes

• AS 4654.1 & 4654.2

  • Deemed-to-satisfy standards for external above-ground membranes 

• Fitness for Purpose

  • Membrane must:

    • Be compatible with adjacent materials

    • Bridge cracks/irregularities

    • Contain water (bathtub effect)

    • Resist UV, movement, chemicals, and abrasion

    • Last the life of the finish

• Design Principles

  • Apply membrane to substrate, not tile screed

  • Always provide falls to drain outlets

  • No ponding

  • Protect from UV/mechanical damage

  • Include slip-sheet/sound-layer where needed

DETAILING

• Drained Cavity (Best Practice)

  • Flat usable surface, concealed drains, serviceable membrane

  • Higher falls possible, no-step thresholds, easy maintenance

• Substances

  • Insitu concrete = best (two-way falls possible)

  • Precast = needs topping slab

  • Timber = avoid in wet zones; flexible membrane essential

• Falls

  • 1:80 – 1:100 typical

  • Tile size and screed thickness affect drainage

  • Accessibility may limit falls

EXPOSURE DESIGN

• Exposed (>3 storeys or ridgeline) → set-downs ≥ 100 mm, overflow pipes, weep holes @ 600 mm max

• Sheltered (<9 m, screened) → reduced detailing pressure

• Flashings ≥ 150 mm up cavity, sealed laps, proper sealants

EFFLORESCENCE CONTROL

• Caused by salt/lime migration from saturated tile beds

• Minimise via: positive substrate fall, stop water entry, penetrant sealer, waterproof adhesives

MEMBRANE PROTECTION

• Prevent construction & service damage using: drainage cells, geotextile fabric, pavers, tiles, or rubber mats

Types of Membrane 

Membrane Flexibility (AS 4654.1)

Terminations & Penetrations 

• Seal and cap leading edges to prevent water behind membrane

• Use reglets (cast-in, formed, or cut rebates)

• Cappings: metal flashings or liquid coatings

• Surface finishes: screed + tile, pavers, or decking

Alternative Systems 

• Crystalline admixtures (e.g., Contec C1): Grow crystals to block pores; cheaper but need careful detailing. Can self-heal small cracks (~1 mm).

Avoid complex joints or poorly controlled concrete.

Week 11

Purpose

• Enable access, movement between storeys and emergency egress

• BCA regulates exits under Section A - Access and Egress 

Stairways as Exits (BCA Definition) 

• Any element providing egress to a road/open space 

  • internal/external stairway 

  • Ramp 

  • Fire-isolated passageway 

  • Doorway to road/open space 

  • Horizontal exit 

Design Requirements 

• Number of stairways: must allow all occupants to evacuate safely 

• Width: sufficient for safe evacuation 

• Fire isolation: depends on: 

  • Building classification 

  • Fire safety systems 

  • Number of connected storeys 

• Governed by NCC Section D – Access and Egress

Stair Materials 

• Choice depends on fire-isolation needs 

• Concrete common: non-combustable, durable under fire exposure 

• Other materials: steel, timber (non-fire-isolated stairs only) 

Purpose of Render

• Provide smooth, decorative finish on masonry/concrete 

• Improve water resistance (not waterproof) 

• Improve sound insulation (thicker coats) 

• Common in apartments and commercial facades 

Render Composition 

Substrate Preparation 

• Clean, key the surface, remove dust/grease 

• Dampen wall before application to improve adhesion 

Application & Coats 

• 1-2 coats depending on substrate & conditions 

• Each coat ≤ 15mm thick 

• 3 days drying between coats 

• Keep render damp during curing to prevent cracking 

Alternative & Acrylic Renders

• Acrylic render: flexible, thin (3–6 mm), adheres to smooth surfaces

• High-build acrylic: forms elastic, waterproof, low-maintenance barrier; bridges cracks and resists CO₂/chemical attack

Render Strength & Compatibility 

• Match strength to substrate:

  • Too strong → cracking along mortar joints

  • 2nd coat must be equal or weaker than 1st

Decorative Finishes 

Control Joints 

• Control where cracking occurs due to drying or movement 

• Achieved via saw cut, tooled groove  or joint bead 

• Located at: 

  • Substrate joints 

  • Changes in material 

  • Large wall areas

Metal Lathe Reinforcing 

• Applied over weak areas or full walls 

• Prevents cracking and improves render strength 

Curing and Protection 

• Prevent rapid drying – causes shrinkage cracks 

• Keep render damp for 3 days; cover with clear plastic sheeting to restrain moisture