What Is a Roof Truss and Its Different Types Explained

A roof truss is a fundamental component of a building's structure, and understanding its types is crucial for any construction project.

Roof trusses are prefabricated frames made of wood or metal that provide support to the roof's weight and distribute it evenly throughout the structure.

There are several types of roof trusses, including Pratt trusses, Howe trusses, and Fink trusses.

Pratt trusses, for example, are commonly used in residential buildings due to their simplicity and cost-effectiveness.

Discover more: Types of Roof Materials

If you're planning to build a vaulted or cathedral ceiling, you'll likely need scissor roof trusses. Their A-frame structure and configuration make them ideal for raised ceiling styles.

A fink truss is the most common type of roof truss, and it's also one of the most affordable options.

Scissor roof trusses are perfect for creating vaulted ceilings that homeowners love. They have lower chords that slope up, creating the peak for a vaulted ceiling.

Their sloping base allows you to raise your ceiling, making your house seem bigger and more elegant. This style of truss is ideal for raised ceiling styles.

Scissor roof trusses have an A-frame structure and configuration in the shape of open scissors. This makes them perfect for building vaulted or cathedral ceilings.

Their structures differ, but the main characteristic of a scissor truss is its sloped base and at least two webbing chords.

Mono trusses are incredibly versatile and can be used to build a roof that allows for more sunlight and visual space.

They're perfect for sheds and garages, as well as creating additional roof tiers and extensions to an existing roof.

Mono trusses are essentially just one half of a full truss, making them a great option for smaller projects.

By using a mono truss, you can create a more open and airy feel in your home, which is especially useful in areas with limited natural light.

The fink truss is the most common type of roof truss, making it a great option for homeowners due to its affordability.

It's designed to be simple yet durable, capable of carrying loads well and spanning long distances.

A fink truss typically has four webbing chords, allowing for some space for plumbing vents or other pipes that might go through your roof.

The W-shape of the fink truss is ideal for shouldering heavy loads along longer spans, making it a sturdy choice for any type and size of a house.

You can find fink trusses made from wood, but they're also available in stainless steel for added durability.

The queen post truss is a popular choice for many homes. It's more common in medium-sized homes because it can accommodate longer spans.

This type of truss has two vertical posts, which sets it apart from the king post truss with its single vertical post.

A roof truss is made up of several key components, each playing a crucial role in its overall structure. The apex is the top-most point of a roof truss, and on a common triangular roof truss, this is the peak of the roof.

The bottom chord is the long horizontal beam that defines the lower edge of a truss, providing strong support for the rest of the structure. It's a vital component that helps keep the truss stable.

The top chord is the top-most beam of a roof truss, and in the most common types of trusses, these beams are slanted and hang over the side of the building.

Additional reading: Roof Beam Span Table

A king post truss is a type of roof truss that's more affordable than others. It uses one less lumber compared to the fink truss.

The king post truss has a central vertical post, also known as the king post. This post is crucial in supporting the structure.

One of the main advantages of a king post truss is that it's ideal for supporting shorter spans. This makes it more suitable for smaller houses and buildings.

The king post truss can still hold weight well, despite being less sturdy than the fink truss. It's a great option for those looking for a more affordable solution.

A king post truss has two webbing chords stemming from the bottom, which provides additional support.

Rafters are a common choice for smaller roof spans or widths, typically less than 16 ft, due to greater economy.

Each rafter spans from the bearing wall to the ridge board at the roof peak, half the distance between the two walls.

Rafters are sized per the building code for span, spacing, load, slope, wood species, and grade.

The continuous ridge board secures the roof peak assembly.

A collar tie is also commonly used in the upper third of the roof height below the ridge board to secure the rafter pairs against uplift, spaced at a minimum 4 ft. o.c.

A unique perspective: Roof Rafter Span Table

Rafters are typically spaced at 16" o.c. or 24" o.c.

The ceiling joist acts as a tension tie to keep the rafters from splaying out under load and also creates a ceiling surface.

Ceiling joists are typically located on the top plate of the walls but may also be located higher to form a partially vaulted ceiling.

A roof truss is made up of several key components, each playing a vital role in supporting the weight of the roof and its contents.

The apex of a roof truss is the top-most point, whether it's the peak of a triangular roof or the top-center point of a flat roof.

The bottom chord is the long horizontal beam that provides strong support to the rest of the truss.

A girder is a main roof truss that supports secondary trusses framing into it.

The heel is a joint in a pitched roof truss where the top and bottom chords meet.

The overhang is the extension of the top chord beyond the heel joint, and it's the distance from the bottom of the roof to the building itself.

The top chord is the top-most beam of a roof truss, and in most common types of trusses, it's slanted and hangs over the side of the building.

A web includes beams that join top and bottom chords in a triangular pattern, capable of carrying tension and compression stress to keep the truss from bending.

Roof trusses are built to last, with a lifespan that often matches the age of your home. Their triangular shape and webbed design make them incredibly strong.

Roof trusses can sustain more weight than rafters and joists, providing top-notch structural support.

Roof truss installation is a crucial step in building a strong and safe roof. The process involves assembling the pre-cut truss components, which are typically made from wood or metal, into the desired shape.

A roof truss is designed to distribute the weight of the roof evenly, which is why proper installation is essential. This is achieved by ensuring that the trusses are spaced at the correct intervals, typically between 24 and 32 inches.

The installation process typically starts at the exterior wall line, where the trusses are anchored to the wall plate. The trusses are then installed in a staggered pattern to provide additional strength and stability.