Are you planning to install a new roof? If you’re a responsible homeowner, you must do your research first. Understand everything there is to know about your roofing system, such as what a roof truss is and why it is important.
As you read about roof design, it’s easy to become confused about the parts of a roof truss or the different types of trusses. We’ll equip you with all there is to know about roof trusses.
In this article, we’ll cover:
Roof Truss at a Glance
A roof truss is a triangular framing that supports the weight of the roof of a structure. Typically made from wood, steel, or both, trusses are bolted together to support the roof. The triangular webbing of these pieces not only supports the roof but also ties the exterior of the walls together.
When installed properly, roof trusses can provide the following benefits:
- Sturdy: Trusses distribute weight evenly, providing a safe and sturdy frame that increases structural integrity.
- Versatile: They can be custom-built to fit any design and scaled to fit any building.
- Lightweight: Created with lightweight materials that make them easy to carry and assemble.
- Cost-efficient: Labor costs are lower since trusses are made in a factory.
- Allows for open-concept design: A truss can support long spans for an open-concept home.
Parts of a Roof Truss
You can think of a roof truss as the sturdy skeleton holding your roof. It consists of a few essential pieces that each play a role in keeping your roof strong and steady. Let’s take a closer look at these parts, from the top chord to the bottom chord, and all the web members that connect them in between.
- Top chord: Placed on the uppermost part of the truss, these beams meet at a point to form the slope of the roof, then are connected to the bottom chord, completing the triangular shape.
- Bottom chord: This is the horizontal beam that defines the bottom part of the truss. The rest of the truss is built and supported by the bottom chord.
- Web bracing: These are beams that connect the top and bottom chords by creating triangular shapes.
- Panel points: Panel points are the locations where the web members intersect with the top and bottom chords. These points are critical for distributing loads effectively and maintaining the structural integrity of the truss.
- Heel: The heel of the truss is the point where the top chord and bottom chord meet at the ends of the truss. This area is typically attached to the building’s exterior walls.
- Peak (or ridge): The peak, also known as the ridge, is the highest point of the truss, where the top chords intersect. It defines the highest point of the roof’s slope.
- King post: In some truss designs, particularly those with a central vertical support member, there may be a king post extending from the top chord to the bottom chord. The king post adds additional support and stability to the truss.
Most Common Types of Roof Trusses
There are many different types of roof trusses that serve a multitude of purposes. Whether you are looking for vaulted ceilings or want the ever-practical attic space for added storage, there is a type of roof truss perfect for your living space needs.
1. Attic Truss
This roof truss uses its webbing to frame the walls of a room, making it easier to convert into a storage area or even a proper room. It usually features a raised heel at the bottom chord, allowing for a flat or sloped ceiling in the lower part of the structure.
2. Cathedral Truss
With this specialized roof truss, you can bring the dramatic effect of a cathedral-style ceiling to your home. It features sloping top chords that meet at the peak of the roof, creating an open and soaring interior space with a high, arched ceiling.
3. Fan Truss
Best used on medium-sized buildings, fan trusses are typically made from steel with webbing combining queen post trusses and fink trusses. This design creates a visually striking and symmetrical arrangement, often resembling the spokes of a wheel.
4. Fink Truss
Used for longer spans and high-pitched roofs, this is the most common roof truss found in residential homes. The webbing on this truss forms a W shape that allows for a heavier load.
5. Gambrel Truss
Designed to support a wide span, these trusses are very versatile but are most often used in farmhouse-style homes. This type of truss not only adds a touch of rustic charm but also offers practical advantages in terms of storage and usable space within the structure.
6. Half or Gable Truss
Forming a pitched or peaked roof, this type of truss consists of two top chords, a bottom chord, and posts. It’s often used for structures with simple and traditional architectural styles. Unlike full roof trusses that span the entire roof, a half truss is designed to cover only one side of the roof, extending from the eave to the ridge of the gable.
7. Hip Truss
A hip roof truss slants downward on all four sides, resembling a pyramid on a square building. This type of truss offers great stability and is often used in areas that often get high winds and snow.
8. King Post Truss
This is the most basic type of truss with the fewest components. With only one central vertical post, these trusses are used for smaller homes or garages that typically span 16 to 26 feet.
9. Mono Truss
This roof truss configuration is designed for buildings with a single-sloping roof surface. It typically consists of a horizontal bottom chord, an inclined top chord, and diagonal bracing members that form a triangular framework.
10. Prefab Truss
A prefab truss, short for prefabricated truss, is manufactured in a factory instead of constructed on-site. It’s only transported to the construction site once it’s ready for installation. These trusses are typically custom-designed to meet specific project requirements, taking into account factors like span, load-bearing capacity, and architectural considerations.
11. Queen Post Truss
Similar to a king post, this truss has two posts extending from the center along with a king post. These often are found in new home construction or larger home additions and can span 16 to 40 feet.
12. Raised Heel Truss
These trusses are raised slightly higher than other types of trusses, which allows for attic ventilation to create an energy-efficient home. They are particularly valued for their energy efficiency, as they provide extra room for insulation, reducing heat loss through the eaves and promoting better ventilation.
13. Scissor Truss
With this type of truss, the bottom chord posts cross each other and connect to the top chord, creating an open scissor shape. It is often used in homes with open floor plans and vaulted ceilings.
Pros and Cons of a Roof Truss
As with anything, there are always going to be positives and negatives. But as you will see from the list, the pros of a roof truss system well outweigh the cons.
Pros of a Roof Truss
- Span: Roof trusses are well-suited for spanning large distances without needing interior support columns or load-bearing walls. They can span up to 60 feet, double the 30-foot span of rafters.
- Strength: Designed to efficiently distribute the weight of the roof evenly, trusses provide strong structural support. They can withstand heavy snow loads, wind forces, and other external pressures, contributing to the long-term stability of the building.
- Eco-friendly: Roof trusses use about 30-50% less timber. Plus, most trusses provide additional space for insulation, contributing to improved energy efficiency by reducing heat loss through the eaves.
- Cost-effective: Reduced on-site labor can contribute to cost savings in both materials and construction time, making roof trusses a cost-effective choice for many projects.
- Somewhat DIY friendly: While it is still a big task, trusses do come with instructions to help with spacing and fastening, making it possible to do it yourself. However, due to the complexity of the project, it’s best to leave the roof construction to a professional roofer.
- Accuracy: Since roof trusses are made in the controlled environment of a factory, there is less room for mistakes. Specifications are put into the software, and the trusses are digitally measured and cut.
- Aesthetics: Some truss designs, like cathedral trusses or scissor trusses, can enhance the visual appeal of the interior space by creating unique architectural features and higher ceilings.
Cons of a Roof Truss
- Transportation and handling: Large truss components may require specialized transportation to the job site and certain equipment for handling and installation, which can add logistical challenges and costs to the project.
- Less flexibility: The structural webbing of a roof truss can limit options to later convert the space into an attic or make it into a room.
- Long-term maintenance: Although trusses are designed for durability, repairs or modifications to the truss system can be challenging and may require specialized expertise.
Cost of a Roof Truss
Naturally, the overall roof truss installation cost will vary depending on your location, as well as the size and type of truss. The typical price range for a new set of roof trusses generally costs around $10,500 to $13,500.
Wood trusses are often used in residential homes and generally cost less than steel. You can expect to pay around $6 to $8 per board foot for a wood truss and between $10 to $12 per board foot for a steel truss.
To give you a better idea, here’s a list of the typical price range for installing the most common types of trusses:
| Type of Roof Truss | Typical Price Range (materials only) |
| Attic | $157 – $467 |
| Cathedral | $250 – $400 |
| Fan | $150 – $175 |
| Fink | $100 – $270 |
| Half | $250 – $450 |
| Hip | $125 – $150 |
| Mono | $75 – $125 |
| Prefab | $100 – $300 |
| Queen post | $50 – $100 |
| Raised tie | $100 – $125 |
| Scissor | $148 – $367 |
Difference Between Roof Truss and Rafters
Roof Truss: 500 / Canva Pro / License
Roof Rafter: tfoxfoto / Canva Pro / License
You may think that a truss sounds a lot like a roof rafter since the two are both essential components in the construction of a roof, but they serve different purposes and have distinct characteristics. Here are the key differences between roof trusses and rafters:
Structure
- Roof trusses are prefabricated, triangular-shaped frames made of wood or steel. They consist of top chords (horizontal members), bottom chords (horizontal members), and diagonal web members that form triangles within the frame.
- Rafters are individual sloping beams that run from the top of the walls to the peak of the roof. They are typically made of wood and form the framework for the roof structure.
Construction
- Designed to meet specific engineering and structural requirements, trusses are typically manufactured off-site and then transported to the construction site.
- Cut and shaped on-site to fit the specific roof design, rafters require skilled carpentry work to ensure they are correctly sized and angled.
Installation
- Trusses are relatively easy to install because they are pre-made to precise specifications. They are lifted into place and secured, reducing the need for on-site cutting and shaping.
- Rafters are installed one by one and require careful measurement and placement. They are often part of traditional roof construction methods.
Span
- Trusses are excellent for spanning long distances without the need for interior support columns or walls. They can evenly distribute the weight across the entire structure.
- Rafters are limited in their span capabilities. Longer spans may require additional support, such as collar ties or ceiling joists, to prevent sagging or roof instability.
Design Flexibility
- While trusses are efficient and strong, they may limit the design flexibility of a roof because they have a standardized triangular shape. However, various truss designs are available to accommodate different architectural needs.
- Rafters offer more design flexibility because they can be adjusted and modified on-site to accommodate various roof shapes and architectural features.
Cost
- Roof trusses can be cost-effective due to efficient manufacturing and ease of installation.
- Rafters may be more labor-intensive and time-consuming to install due to their on-site customization, which can affect construction costs.
FAQ About Roof Trusses
Yes, you can customize your roof truss to accommodate certain architectural designs and preferences. Some options for customization include modifying the shape, pitch, span, and layout of the truss.
Similar to how a skeleton works, trusses provide stability and structural support to your roofing system. Depending on the structural framework, a roof truss can help distribute the roof’s weight so it wouldn’t put much stress on the home’s foundation and walls. Remember to consult a reliable structural engineer before constructing your new roof.
In residential construction sites, roof trusses can be installed using a crane or manual handling methods. For smaller projects, manual techniques may be more cost-effective. However, crane-assisted installation may be better and faster for larger homes.
Ready For a New Roof?
Roof trusses are available in different shapes and sizes, offering strength, stability, and even a touch of architectural flair. Armed with knowledge about trusses, you are now ready to take the next step. Let us help you find a reputable roofing company in your area.
Main Image Credit: DustyPixel / Canva Pro / License
