The fundamental difference between joists and noggins lies in their primary function, orientation, and placement within a timber framework. Joists are primary structural members that support loads, while noggins are shorter, secondary members installed between joists (or studs) to increase strength and stability.
Understanding Joists
Joists are horizontal structural components, typically made of timber, engineered wood, or steel, used to support floors, ceilings, or roofs. They are laid parallel to each other at regular intervals, spanning between walls, beams, or foundations, and are designed to transfer the imposed loads (dead loads from the structure itself and live loads from occupants and furnishings) to the supporting elements below.
- Primary Function: To carry and distribute vertical loads.
- Orientation: Typically run horizontally and parallel to each other.
- Key Characteristics:
- Form the main support for a floor or ceiling deck.
- Are sized based on span length, load requirements, and material properties.
- Crucial for the structural integrity of a building's horizontal surfaces.
Understanding Noggins
Noggins, also known as blocking or dwangs in some regions, are shorter pieces of timber or metal installed horizontally and perpendicularly between joists or studs. As per the reference, "Noggins are fixed between joists or studs to increase the strength and stiffness of the framework." They act as bracing and stiffening elements, preventing the primary members from twisting, buckling, or moving independently.
- Primary Function: To provide bracing, prevent twisting, and enhance the overall stiffness and strength of the framework.
- Orientation: Fixed horizontally, perpendicular to the joists or studs they connect.
- Key Characteristics:
- Improve load distribution across multiple joists.
- Reduce bounce and vibration in floors.
- Can provide fire breaks or fixing points for services.
- Are essential for creating a rigid and stable structural system.
Key Differences at a Glance
To illustrate the distinction clearly, here's a comparative table:
| Feature | Joist | Noggins |
|---|---|---|
| Primary Role | Main load-bearing structural support | Bracing, stiffening, and anti-twist support |
| Orientation | Horizontal and parallel | Horizontal and perpendicular to joists/studs |
| Placement | Forms the main span of a floor/ceiling | Fixed between joists or studs |
| Length | Long, spanning a distance | Short, fitting between two adjacent members |
| Function | Carries vertical loads directly | Enhances stability and strength, distributes load |
| Impact | Structural integrity of the surface | Reduces bounce, prevents twisting, adds rigidity |
Practical Applications and Importance
Both joists and noggins are integral to sound construction, working in synergy to create robust structures.
- Floor Construction: In a typical timber floor, joists run the length or width of the room, supporting the floorboards. Noggins are then inserted between these joists at mid-span or specified intervals. This setup significantly reduces floor bounce and helps distribute heavy point loads (like a large appliance) across several joists, rather than concentrating it on just one.
- Wall Framing: While the reference highlights their use with joists, noggins are also commonly used between wall studs. Here, they provide lateral bracing, preventing the studs from bowing or twisting, and also offer convenient fixing points for internal wall linings or fixtures.
- Roof Construction: Similar principles apply in some roof framing designs, where noggins can be used to brace rafters or ceiling joists.
By incorporating noggins, builders ensure that the structural framework is not only strong enough to bear vertical loads but also rigid and stable enough to prevent lateral movement and twisting, contributing to the longevity and safety of the building.
