Whether you're constructing a new house, adding onto an existing property, or working on a multi-unit project, the kind of roof truss you choose plays a crucial role.
But what exactly is a roof truss? In this guide, we?ll explain what roof trusses are and what to consider when selecting the ideal one for your building needs.
What Function Does a Roof Truss Serve?
A roof truss is a pre-engineered framework designed to support the roof of a structure. These systems are carefully calculated and built to provide both strength and visual appeal to a building.
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Roof trusses are typically made from timber, steel, or a mix of both. They consist of connected components that are fastened together to bear the weight of roofing materials like tiles or shingles.
Unlike traditional rafters, roof trusses are designed using computer software and assembled in controlled factory settings, resulting in consistent quality, structural reliability, and reduced cost?contributing to their growing popularity.
Each roof truss consists of three primary elements: top chords, bottom chords, and internal bracing (webs). The size and spacing of trusses are determined based on the required load, span, and building design.
Advantages of Roof Trusses
Roof trusses are fundamental components in modern construction and offer numerous benefits:
Strong and Supportive
A roof truss evenly distributes the roof load, enhancing the building?s structural soundness and overall safety.
Adaptable
With a wide range of truss styles available, they can accommodate any architectural size?from small garden sheds to large residential properties. Trusses can also be tailored to match specific project requirements.
Lightweight
Thanks to the materials used, roof trusses are light in weight, making them easy to transport and install on-site.
Budget-Friendly
Because roof trusses are produced off-site, on-site labor demands are lower, helping to cut down on overall building expenses.
Ideal for Open Floor Plans
Some types of roof trusses support long spans, making open-concept designs possible without interior load-bearing walls.
Key Parts of a Roof Truss
While roof trusses vary in design and size, they all include core
structural components:
- Bottom Chord: The horizontal member along the base of the truss.
- Top Chord: The angled beams at the top (also called rafters).
- Webs: Diagonal or vertical members that connect the top and bottom chords, adding strength and stability.
- Apex (Peak): The highest point where top chords meet.
- Joints: Points where chords and webs intersect and are joined.
- King Post: A central vertical post used in simpler truss styles.
- Overhang: The extension of the top chord beyond the edge of the truss.
- Heel: The area where the top and bottom chords connect near the wall plate.
Different Types of Roof Trusses
There are several types of roof trusses, each offering specific advantages. Selecting the right one depends on your budget, design goals, and structural needs. A professional roofing contractor can help guide you through the decision process.
King Post Truss
One of the most frequently used options, king post trusses span 16 to 26 feet and are ideal for small to mid-sized residential properties.
Queen Post Truss
Queen post trusses span between 16 and 40 feet. They are a stable and straightforward solution, suitable for a variety of residential designs.
Fink Truss
Widely used in homes, Fink roof trusses are perfect for achieving longer spans and steep roof pitches.
Raised Heel Truss
This truss improves energy efficiency by allowing ample space for attic insulation and ventilation, especially in modern energy-conscious builds.
Scissor Truss
Known for enabling dramatic vaulted ceilings, scissor roof trusses have angled bottom chords that create a unique open look.
Hip Truss
With sloped sides meeting at a central ridge, hip trusses are excellent for areas with high winds or heavy snowfall due to their added stability.
Attic Truss
Also called ?room-in-attic? trusses, these are designed to provide additional interior space?ideal for garages, sheds, or homes needing an extra room.
Mono Truss
Shaped like half of a full truss, mono trusses are often used for roof extensions or to add secondary tiers to an existing roof.
Gambrel Truss
Common in barns and farmhouse-style buildings, gambrel trusses allow for extra overhead space thanks to their two-slope design.
Gable Truss
Typically placed at each end of the roof structure, gable trusses help secure siding and maintain the integrity of the overall framework.
Roof Truss vs. Rafters: What?s the Difference?
Both trusses and rafters provide roof support, but they differ in design and construction.
- Trusses are pre-fabricated using CAD software and assembled off-site, offering greater uniformity and lower costs. However, they require delivery and may be challenging to install in remote or difficult-to-access areas.
- Rafters are custom-built on-site by skilled laborers. While more labor-intensive, rafters offer greater attic space and future modification flexibility.
In short, roof trusses are cost-effective and time-saving but less adaptable post-installation. Rafters provide customization potential but require more on-site work and higher labor costs.