Building Products and Types Overview

Timber building products fall into three broad categories: solid timber, engineered wood products (EWPs), and hybrid or composite systems. Each offers distinct advantages based on application, scale, and performance requirements. Selecting the right product is the first step in delivering structural, aesthetic, and environmental performance.

1.1 Solid Timber Products

Sawn timber refers to solid wood milled directly from logs into structural sections. It is widely used for framing, cladding, decking, and joinery.

Sawn Timber

• Common species:
  • Radiata Pine (softwood); Spotted Gum, Blackbutt (hardwoods)
• Strengths:
  • Readily available, cost-effective, easily worked
• Considerations:
  • Typically requires grading and, in many cases, treatment for durability and termite resistance.

Figure 1: Sawn timber profiles (WS TDG 46 p71)

Timber Rounds and Poles

These products are minimally processed from whole logs and used in fencing, piling, landscaping, and utility structures.

• Strengths: High natural strength and visual appeal in rustic or rural applications
• Considerations: Irregular geometry limits standardisation and engineered connection options.

Figure 2: Timber Rounds and Poles (WS TDG 46 p71)

1.2 Engineered Wood Products (EWPs)

EWPs are manufactured timber products optimised for high strength, dimensional stability, and efficient material use. They play a critical role in both conventional and advanced timber construction systems.

Laminated Veneer Lumber (LVL)

Made by bonding multiple thin veneers of wood together with adhesives, LVL offers consistent strength and stiffness across long spans.

• Applications: Beams, lintels, trusses, formwork
• Notes: Factory-controlled production ensures predictability; often used in hybrid systems.

Figure 3: LVL Elements (WS TDG 46 p69)

Glue Laminated Timber (Glulam or GLT)

Formed by laminating individual timber laminations into structural members, Glulam allows for curved or cambered shapes and long spans.

• Applications: Beams, columns, arches
• Notes: May be supplied in appearance grades for exposed use.

Figure 4: GLT elements (WS TDG 46 p73)

Cross-Laminated Timber (CLT)

CLT consists of layers of timber boards glued at right angles, forming structural panels for floors, walls, and roofs.

• Applications: Mass timber buildings, prefabricated structures
• Notes: Offers excellent stiffness, dimensional stability, and rapid assembly potential.

Figure 5: CLT elements (WS TDG 46 p74)

Oriented Strand Board (OSB) & Plywood

Sheet-based timber panels formed from veneers (plywood) or compressed strands (OSB).

• Applications: Bracing, flooring, roofing, linings
• Notes: Select Type A or B bonds as required for exterior or interior use.

Figure 6: OSB elements (WS TDG 46 p81)

1.3 Composite & Hybrid Timber Systems

Timber-Concrete Composite (TCC) Floors

Combine timber panels or joists with a concrete topping slab to achieve greater strength and stiffness.

• Applications: Mid-rise floors, commercial buildings
• Notes: Requires specialist connectors and acoustic detailing.

Figure 7: TCC floors (WS TDG 46 p87)

Steel-Timber Hybrid Systems

Use steel frames in combination with timber elements to support long spans or high loads.

• Applications: Warehouses, shopping centres, atria
• Notes: Coordination of connection detailing is critical.

Key Takeaways

• Solid timber products (e.g. sawn timber, poles) are widely used for framing, joinery, and cladding, but may require treatment or grading depending on exposure and structural needs.
• Engineered wood products (EWPs) such as LVL, Glulam, and CLT offer enhanced strength, stability, and prefabrication potential. Each product type suits different structural roles-beams, panels, or curved forms.
• CLT is unique among EWPs as a planar system used for walls, floors, and roofs in mass timber construction. It enables rapid assembly and integrated detailing.
• Composite and hybrid systems combine timber with concrete or steel for improved span capacity, acoustic control, and fire separation in complex buildings.
• Product selection should be based on application and system role-not just material type.

Performance characteristics such as moisture resistance, fire safety, and durability are covered in detail on related subpages.

Timber construction is rapidly evolving, bridging traditional techniques with modern engineering innovations. Choosing the right structural system ensures code compliance, cost-effectiveness, and long-term performance in timber buildings.

Timber construction systems range from lightweight framing to large-format mass timber and hybrid assemblies. The choice of structural system depends on building type, height, desired speed of construction, and performance requirements such as fire resistance, acoustic separation, and thermal efficiency.

This section introduces the primary timber systems in use across Australia and provides links to detailed design and compliance guidance.

2.1 Light Timber Frame Construction

Overview
Lightweight timber framing is the dominant construction method for Class 1 residential buildings and increasingly used in low-rise and medium-rise commercial and institutional projects. Framing typically uses MGP or F-grade softwoods, assembled into walls, floors, and roof trusses.

Features

• Built with repetitive stick-framed elements (studs, joists, rafters)
• Bracing is provided by sheet products like plywood or fibre cement
• Compatible with prefabricated wall and floor cassettes

Figure 8: Timber Framed Construction (Speedpanel and USG Boral) (WS TDG 01 p5)

2.2 Massive Timber Systems 

Overview:
Mass timber refers to any timber element with a minimum cross-section thickness ≥75 mm. This includes products like CLT, Glulam panels, and thick LVL, which form structural walls, floors, or roofs.

Panel-Based Systems
CLT and other panelised systems are used for loadbearing walls, floors, and roofs. They are dimensionally stable and suitable for prefabrication.

Post-and-Beam Systems
Massive Glulam or LVL members are used in grid layouts to support long-span roofs or open-plan interiors.

Figure 9: CLT Construction (Strongbuild) (WS TDG 16 p7)

2.3 Post-and-Beam Construction

Overview
This system uses discrete vertical and horizontal members (columns and beams) to form a structural frame. It is ideal for buildings requiring long spans or flexible internal layouts, such as offices, halls, or commercial tenancies.

Features

• Typically uses Glulam or LVL for structural members
• Allows for exposed timber interiors with visual-grade finishes
• Compatible with prefabricated infill walls, floor panels, or roof diaphragms

Figure 10: Post and Beam construction (WS TDG 46 p48)

2.4 Prefabricated and Modular Timber Construction

Overview
Prefabricated systems use off-site manufacturing to deliver walls, floors, and even complete room modules (volumetric units). This approach improves quality control, reduces site labour, and shortens construction timelines.

System Types

• Panelised: wall, floor, and roof cassettes including insulation and services
• Volumetric: 3D modules like hotel rooms or classrooms craned into place
• CLT Modular: increasingly used for mid-rise housing and repeatable units

Key Takeaways

• Light timber framing remains the most common solution for housing and low-rise buildings, supporting fast, cost-effective construction.
• Mass timber systems (CLT, Glulam, LVL) provide robust structural solutions for mid-rise and hybrid buildings, with integrated fire and acoustic design potential.
• Post-and-beam systems support wide spans and flexible layouts, especially in commercial and institutional projects.
• Prefabricated and modular timber offers precision, speed, and repeatability-suitable for both residential and public infrastructure.
• Choose the system based on building type, span needs, and construction logistics-not just product type.

Timber’s lightweight nature, prefabrication potential, and fire-resistant capabilities make it an ideal material for modern, sustainable construction across all major building classes.

Timber construction systems are now used across nearly all NCC building classes-from detached houses to mid-rise apartments and large-span commercial buildings. Each building type places different demands on timber systems in terms of structure, fire resistance, durability, acoustics, and moisture control.

This section outlines the most common structural approaches by building class, with links to deeper design guidance.

3.1 Residential Buildings (Class 1, 2, 3 & 4)

Class 1a/1b: Detached Houses, Townhouses, Granny Flats

Typical systems:

• Light timber frame with timber trussed roofs
• Joisted or cassette timber floors
• Timber decking, stairs, and window joinery

Advantages:

• Fast, cost-effective construction using widely available materials
• Compatible with prefabricated wall and roof panels
• Readily meets Deemed-to-Satisfy (DTS) solutions for fire and energy compliance
• Supports high-performance detailing for thermal comfort and passive design

Performance:

• NCC-aligned framing and detailing guides are widely available
• Requires moisture-aware detailing at subfloors, balconies, and cladding interfaces
• H1 or H2-treated framing required in termite-prone zones

Class 2/3: Apartments and Hotels (Multi-residential)

Typical systems:

• Fire-protected CLT and LVL wall and floor systems (up to 25 m effective height)
• Light timber frame construction for 3-4 storey walk-ups
• Cassette floors, modular bathrooms, and prefabricated wall assemblies

Advantages:

• Rapid construction using prefabricated timber systems
• Reduced structural weight supports vertical extensions and soft-soil sites
• Excellent acoustic separation and thermal performance with correct build-ups
• Lower site disruption for infill and tight-access developments

Performance:

• NCC Volume 1 permits fire-protected timber construction up to 8 storeys
• Acoustic performance must be designed to meet Rw + Ctr and Ln,w targets
• Vapour control is critical in sealed or highly insulated buildings

Class 4: Mixed-use Residential Over Commercial

Typical systems:

• Concrete or steel podium
• Timber residential levels above using CLT or light framing
• Separation layers for fire and acoustic compliance between uses

Advantages:

• Efficient vertical zoning with lightweight superstructure
• Simplified detailing at interfaces with properly coordinated hybrid systems

Performance:

• Requires fire separation and acoustic decoupling between Class 5/6 and Class 2/3 zones
• Structural interfaces must manage differential movement and moisture exposure

3.2 Commercial Buildings (Class 5 & 6)

Class 5: Offices

Typical systems:

• Glulam or LVL post-and-beam frame
• CLT or cassette floor systems
• Integrated acoustic and services zones within floor build-ups

Advantages:

• Long-span layouts with minimal internal supports
• Visual-grade timber enhances biophilic and wellness outcomes
• Prefabrication supports tight construction timelines and low-disruption upgrades

Performance:

• Fire compliance via encapsulation or Performance Solution with charring
• Acoustic zoning required between tenancy levels and meeting spaces
• Column-fire detailing and floor edge sealing are essential for NCC compliance

Class 6: Shops and Retail Premises

Typical systems:

• Portal frames (Glulam or LVL)
• CLT or cassette floors over shop fitouts
• Structural plywood for bracing and sheathing

Advantages:

• Open spans and flexible layouts
• Faster tenancy turnover with dry construction and minimal wet trades
• Reduced roof weight for suspended signage, services, or solar integration

Performance:

• NCC fire and smoke separation may require encapsulation or hybrid elements
• Impact sound and footfall vibration in mezzanine levels must be addressed

3.3 Education and Assembly (Class 9b)

Typical systems:

• CLT floors, walls, and roofs for modular classrooms or permanent facilities
• Glulam/LVL post-and-beam with acoustic soffits and ceiling systems
• Structural ply or OSB for bracing in hybrid applications

Advantages:

• Quiet, warm, and healthy interiors support concentration and occupant wellbeing
• Speed of construction suits school holidays or tight programs
• Modules can be delivered pre-lined with integrated services

Performance:

• NCC Volume 1 acoustic, fire and crowd safety requirements apply
• Mass timber systems require moisture protection and post-install inspection access

3.4 Industrial Buildings (Class 7 & 8)

Warehouses, Factories, Carparks

Typical systems:

• Glulam or LVL portal frames for long spans and open bays
• CLT mezzanines and walls in light-industrial fitouts
• Structural ply or OSB for shear walls and wind bracing

Advantages:

• Rapid erection of large-span structures with minimal wet trades
• Fire-resisting detailing for carparks and light-industrial workshops
• Low embodied carbon and long service life with correct maintenance

Performance:

• Fire Performance Solutions are typically required for open carparks or warehousing
• Detailing must address moisture, vibration, and chemical exposure risks

Key Takeaways

• Class 1 housing is well-supported by traditional light framing and prefabricated components.
• Mid-rise residential and hotels benefit from CLT and LVL systems that meet acoustic and fire requirements with rapid build times.
• Commercial and institutional buildings use exposed post-and-beam systems for long spans and natural interiors.
• Industrial timber structures are fast to construct and perform well with the right moisture, fire, and span detailing.

Understanding timber’s structural, fire, acoustic, and environmental performance ensures safe, compliant, and long-lasting timber buildings in modern construction.

Timber is a high-performance construction material and its behaviour under load, moisture, fire, sound, and thermal stress must be well understood and carefully managed. This section provides a concise overview of key performance areas in timber design and construction.

Each topic summarised here is explored in greater technical depth on dedicated subpages.

4.1 Structural Strength and Stability

Overview
Timber products-especially engineered products like CLT, LVL, and Glulam-offer excellent strength-to-weight ratios and can be used for both short-span and long-span structural systems.

Design Considerations

• CLT panels act as diaphragms and loadbearing plates
• LVL and Glulam act as high-performance beams and columns
• Framed systems rely on bracing and fixing patterns to resist racking and wind loads
• Creep, shrinkage, and interface movement must be accounted for in long-term design

4.2 Moisture Resistance and Durability

Overview
Timber is hygroscopic-it absorbs and releases moisture in response to humidity, rain, vapour diffusion, and condensation. Moisture is a defining factor in long-term serviceability.

Design Considerations

• Moisture above 20% enables fungal decay and corrosion of fasteners
• End grain must be sealed, and cavities must be ventilated
• Vapour-permeable membranes and drainage paths reduce risk
• Timber selection must match durability class and hazard exposure

4.3 Fire Performance

Overview
Timber-especially mass timber-performs predictably in fire due to its insulating char layer. Modern detailing allows timber buildings to meet Fire Resistance Levels (FRLs) up to 90 or 120 minutes.

Design Considerations

• CLT must be encapsulated or protected, or justified via Performance Solution
• Glulam and LVL require minimum section thickness or linings for compliance
• Charring rates and adhesive behaviour are critical in design
• Cavity barriers, penetrations, and joints must not undermine system integrity

4.4 Acoustic Performance

Overview
Timber’s low mass can lead to sound transmission unless layered and decoupled effectively. Acoustic detailing is essential in multi-occupancy buildings and schools.

Design Considerations

• Floors require floating screeds or suspended ceilings to control impact noise
• Walls should use staggered studs, batts, and double linings to manage flanking
• Penetrations (e.g. GPOs, pipes) must be sealed to maintain Rw ratings
• NCC requires compliance with airborne and impact sound targets for walls and floors

4.5 Thermal Performance and Energy Efficiency

Overview
Timber provides natural insulation and enables high-performance thermal assemblies. It supports net-zero energy goals with reduced thermal bridging and high airtightness.

Design Considerations

• Mass timber buffers internal temperature swings (thermal mass)
• Lightweight framing enables high R-value insulation in walls and roofs
• Detailing at junctions must prevent thermal bridging or air leakage
• Vapour control layers must be placed according to climate zone

Key Takeaways

• Timber systems must be designed with awareness of moisture, fire, and acoustic risks, especially in tightly sealed, multi-storey, or high-humidity applications.
• Mass timber systems must address detailing at joints, interfaces, and cavities for fire, acoustic, and moisture compliance.
• Durability depends on matching species or treatment class to the exposure risk, with good drainage and ventilation.
• Thermal and energy efficiency is a strength of timber, especially when prefabricated systems are sealed and detailed with care.

By integrating engineering, protective detailing, and compliance strategies, timber buildings can achieve exceptional durability, fire safety, sound insulation, and energy efficiency, ensuring long-term functionality and sustainability.

Timber buildings rely on a diverse array of connection systems to ensure strength, stability, and serviceability. From traditional joinery to modern engineered fasteners, the right connection method depends on the product type, structural system, and exposure conditions.

This section outlines the main categories of timber connections and how they’re applied across different building systems. More detailed design and fabrication guidance is provided in linked subpages.

5.1 Mechanical Fasteners (Nails, Screws, Bolts)

Overview
Mechanical fasteners are the most common connection type across light timber framing, engineered wood, and mass timber systems. They provide structural fixity, ease of installation, and flexibility on site.

Applications

• Nails: Framing, sheathing, decking
• Screws: CLT panels, flooring, concealed connections
• Bolts: Post-and-beam joints, long-span trusses, hybrid interfaces
• Self-tapping screws: Mass timber assemblies, including diagonal and inclined fasteners for moment resistance

Design Considerations

• Embedment length, edge distance, and spacing determine capacity
• Fastener material must be compatible with timber treatment (e.g. HDG or stainless for H3+ treated pine)
• Pre-drilling is recommended in dense or appearance-grade hardwoods

Figure 11: Nails, Screws, Bolts (WS TDG 52 p9)

5.2 Metal Connectors (Plates, Brackets, Hangers, Dowel Systems)

Overview
Metal connectors provide increased load-carrying capacity and can simplify assembly in both light and heavy timber systems.

Applications

• Gang-nail plates: Prefabricated trusses
• Joist hangers: Floor and deck framing
• Brackets and angle plates: Post-to-beam or wall-to-floor junctions
• Dowel-type connectors: High-strength connections in Glulam or CLT

Performance Notes

• Connections must allow for movement and seasonal shrinkage
• In fire-rated applications, connectors may need to be embedded or protected by charring timber or linings
• In exterior or moist environments, galvanised or stainless steel is required to prevent corrosion

5.3 Adhesive and Composite Bonding

Overview
Adhesives are used extensively in engineered wood products and increasingly in panel-based connections. They enable strong, invisible joints and improve air-tightness and vibration performance.

Applications

• CLT and LVL manufacture (PUR, MUF, PRF adhesives)
• Glued scarf or finger joints in long-span members
• Site-applied glues for acoustic or vapour sealing at CLT interfaces (used selectively)

Considerations

• Adhesive compatibility with coatings, treatments, and structural movement must be confirmed
• Site bonding requires tight moisture and temperature control to ensure curing and bond strength

5.4 Traditional Timber Joinery Methods

Overview
Although less common in commercial buildings, traditional joinery techniques are still relevant in architectural projects, restoration works, and dowel-laminated timber (DLT) systems.

Examples

• Mortise and tenon
• Lap and scarf joints
• Timber-only dowel and peg connections

Advantages

• No reliance on metal components-minimises thermal bridging and avoids galvanic corrosion
• Suits exposed timber architecture, heritage repairs, or carbon-sensitive design philosophies

5.5 Prefabrication and On-site Assembly Techniques

Overview
Prefabricated timber elements are precision-manufactured off-site and assembled rapidly on-site with pre-defined connection details. Connection accuracy and sequencing are critical for speed and performance.

Key Elements

• CLT panel edge profiles (half-laps, splines, scarf joints)
• Pre-installed hardware or sleeves for concealed connections
• Shop-drawn fastener locations to minimise site adjustment

Assembly Considerations

• Site tolerances must account for timber movement and minor misalignments
• Weather protection is essential during assembly, especially for CLT and Glulam
• Crane planning, lift points, and temporary bracing must be coordinated early

Key Takeaways

• Connection types vary by system: nails and screws in light framing; bolts, dowels, and concealed fixings in mass timber.
• Fire resistance, moisture exposure, and movement must be considered in connection detailing.
• Prefabrication requires exact tolerances and well-coordinated sequencing of connection points.
• Corrosion resistance is critical when working with treated timber or exposed environments.

Timber connections are essential for ensuring structural strength, fire compliance, durability, and construction efficiency. Understanding the right connection method for each timber system enables safe, cost-effective, and long-lasting timber buildings.