In residential construction, framing is the skeleton of the building. It supports the roof, walls, and floors, providing the structure with strength and stability. Section 2 of the Australian Standard 1684.2:2021 offers clear guidance for builders on the key elements that make up timber-framed houses. In this post, we’ll break down the essential concepts of this section, which covers everything from terminology to structural requirements, making it easier to understand even for those who aren’t familiar with construction.
In residential construction, framing is the skeleton of the building. It supports the roof, walls, and floors, providing the structure with strength and stability. Section 2 of the Australian Standard 1684.2:2021 offers clear guidance for builders on the key elements that make up timber-framed houses. In this post, we’ll break down the essential concepts of this section, which covers everything from terminology to structural requirements, making it easier to understand even for those who aren’t familiar with construction.
In residential construction, framing is the skeleton of the building. It supports the roof, walls, and floors, providing the structure with strength and stability. Section 2 of the Australian Standard 1684.2:2021 offers clear guidance for builders on the key elements that make up timber-framed houses. In this post, we’ll break down the essential concepts of this section, which covers everything from terminology to structural requirements, making it easier to understand even for those who aren’t familiar with construction.
Section 2 begins by introducing the general principles behind framing members. It outlines the key parts of a timber-framed house and defines their roles within the structure. This includes everything from the floor and wall framing to the roof framing, emphasizing how these components work together to bear the loads of a building. The goal here is to ensure that all framing members are sized and assembled correctly to carry the expected loads and provide sufficient support. A strong frame is crucial for a home’s durability and safety, especially in areas with challenging weather conditions.
This section introduces the terminology related to various framing components, illustrated by a series of diagrams. The terms are crucial for understanding how different parts of the house's structure interact. Here’s a breakdown of some key terms: Rafter: A sloped beam that supports the roof. Fascia: The horizontal board attached at the end of roof rafters. Lintel: A horizontal beam placed over openings like windows and doors. Stud: Vertical beams that form the walls, holding up the ceiling and roof. Termite Shield (Antcap): A metal barrier placed between the foundation and the building to prevent termites from entering. Figures 2.1 through 2.7 offer detailed diagrams of various framing configurations, including floor, wall, and roof framing, making it easier for builders to visualize how these components fit together in a house.
Lamination refers to combining multiple pieces of timber to create a stronger, larger section. This section explains how vertical lamination is used to meet the required sizes for larger structural elements. There are two key types of vertical lamination: Vertical Nail Lamination: This process uses thinner pieces of timber nailed together to achieve the necessary width and strength. The laminations must be from the same timber type and stress grade, and nails or screws are staggered to ensure stability. Lamination of Spaced Ring Beams: Ring beams made up of spaced members are laminated with nails or screws to provide strong support in walls or roofs, especially around large openings.
This subsection covers how studs (the vertical beams that support walls) can be laminated in areas requiring extra strength, such as near windows or doors, where concentrated loads occur. Stud lamination uses multiple timber pieces nailed together to create a wider support beam. The spacing and type of nails are specified to ensure the structure can handle the additional weight.
Introduction In residential timber-framed construction, the substructure is the part of the building below the floor, supporting the entire structure. It includes footings, stumps, and posts that transfer the load of the building down to the ground. Proper site preparation and the right selection of substructure components are crucial for stability and durability. Section 3 of the Australian Standard 1684.2:2021 outlines the requirements for preparing the site, ensuring good drainage, and selecting appropriate footings and supports based on the soil conditions.
This section establishes the basic requirements for site preparation and subfloor supports for timber-framed houses. It uses soil-bearing capacities to determine suitable footing sizes, referencing AS 2870 for guidance. The goal here is to ensure that the substructure can handle the weight of the building, both from above (roof, walls, floors) and from lateral forces like wind.
Before construction begins, it's essential to clear the site and ensure that the timber framing is protected from dampness and pests, such as termites. This involves careful drainage and clearing of any potential hazards to the footings or the building’s drainage systems.
The site must be cleared of any logs, stumps, roots, or other debris that could attract termites or damage the building’s footings. Construction waste and other materials should also be removed to minimize termite risks.
Effective drainage is critical to prevent water pooling under the structure. Surface water must be directed away from the building using grading, filling, or drainage channels. This helps protect the substructure from water damage and prolongs the building's lifespan.
This section ensures that there is enough clearance between the ground and the subfloor to allow proper ventilation. Good ventilation is important to prevent damp conditions that could lead to rot or termite infestation. For specific requirements, builders should refer to the National Construction Code.
Termite protection is a vital consideration in timber-framed construction. Builders need to follow the National Construction Code for specific guidelines on protecting the substructure from termites, which can severely damage timber.
Various timber species and durability classes can be used for the floor and subfloor framing, provided there is adequate ventilation and protection from moisture. In more damp environments or where timber is in contact with the ground, builders need to refer to Appendix B for additional guidance on timber selection.
The substructure must be adequately braced to resist the loads applied to it, including vertical and lateral forces. This includes making sure that the footings and subfloor supports are strong enough to keep the building stable. Section 8 of the standard provides detailed guidance on bracing requirements.
Subfloor supports include stumps, posts, and piers that bear the vertical loads from the structure above. This section outlines the process for determining the correct size and capacity of these supports based on the load they need to carry.
The capacity of subfloor supports is closely tied to the soil type. This section applies to soil types classified as A, S, M, or H with a minimum bearing capacity of 100 kPa. More difficult soil conditions (like types E or P) require professional advice.
To size the footings properly, builders must follow a three-step process: Determine the dead loads (permanent weight of the building). Calculate the live loads (weight from furniture, people, etc.). Use these values to determine the required size for footings and subfloor supports.
This section helps builders calculate the total vertical load on footings, considering both permanent (dead) loads and temporary (live) loads. It provides formulas for calculating the load contributions from the floor, walls, and roof.
The total vertical gravity load is calculated using the formula: P = G + 0.5Q, where G is the sum of the permanent loads, and Q is the sum of the live loads.
Once the load is known, the required size of the footing can be determined using Table 3.2, or the footing’s bearing area can be calculated with the formula: A = P / 100, where P is the total vertical bearing load in kN.
In areas classified as wind classifications N1 or N2, specific requirements are provided for selecting stumps, posts, and footings. The footings need to transfer both vertical and lateral loads to the foundation to ensure the structure can withstand wind forces.
Footings are categorized into five types, depending on the bearing capacity of the soil. This classification helps builders choose the right footing type for a given soil condition.
This subsection outlines the requirements for stumps and posts, including their size, height, and embedment depth. Stump and post sizes vary based on the footing type, and the embedment must be at least 450 mm deep.
This subsection provides tables that show the maximum permissible load widths and bearer spans for each footing type. These values help ensure that the footings and supports are correctly sized to handle the building’s load.