Timber Frame Scissor Truss: A Comprehensive Guide

A timber frame scissor truss is a type of roof truss that uses a unique design to provide added strength and stability to a building.

This design features two sloping sides that meet at a peak, creating an "X" shape.

The scissor truss is often used in timber frame construction due to its ability to provide a clear span of up to 40 feet without the need for interior columns.

It's a popular choice for large open spaces, such as living rooms and great rooms.

Timber frame scissor trusses beautifully complement vaulted ceilings on the inside of your home and deep eave overhangs on the outside.

The Scissor Truss system provides extraordinary character, a feature that designers and architects familiar with timber frames often appreciate.

Repeating the Scissor Truss system throughout the length of your home's interior gives the open spaces extra height, creating a more open and airy living space.

A vaulted ceiling can provide a more open and airy living space and will fit the style of most any home decor.

Timber frame scissor trusses are designed by an engineer to ensure the truss will hold up the roof, providing a safe and sturdy structure.

By using timber frame trusses, you can span a large area and create a dramatic effect at the same time, adding value to your home or building.

A scissor truss is a visually appealing option for a vaulted ceiling, offering a spacious and open feel. It gets its name from the resemblance to an open pair of scissors, with interlocking diagonal beams that meet in the center of the truss.

The scissor truss design is unique, with two beams going from the lower part of one rafter up to the opposite rafter, notched to fit together like scissors. This design provides extraordinary character, making it a popular choice among designers and architects familiar with timber frames.

A scissor truss can beautifully complement vaulted ceilings on the inside of your home and deep eave overhangs on the outside, giving the open spaces extra height when repeated throughout the length of your home's interior.

A scissor truss is a type of truss that offers a beautiful option for a vaulted ceiling, appearing more visually open than some other types of trusses.

The double bottom chords of a scissor truss meet in the center of the truss, crossing over the vertical king post and joining the top chords.

The name "scissors truss" comes from its resemblance to an open pair of scissors.

A scissors truss is a visually appealing option for a vaulted ceiling, offering a spacious and open feel. It gets its name from the resemblance to an open pair of scissors, with interlocking diagonal beams that add to its unique charm.

The double bottom chords of a scissors truss meet in the center, crossing over the vertical king post and joining the top chords. This design gives it a more open appearance than some other types of trusses.

A scissors truss is typically exposed to the snow load only on the rafters, which is a key factor in its design. The load is often simplified to 2 kN/m, which is equal to a snow load of 1 kN/m and a truss spacing of 2m.

To calculate the compression and tension forces of the truss members, we need to use the 3 equilibrium equations. This involves giving the nodes and bars some indices for easier identification later in the internal force calculation.

The point loads applied to nodes (a) and (c) are calculated as 2.67 kN, while the point loads applied to nodes (d) and (e) are calculated as 4.0 kN. The point load applied to node (f) is calculated as 2.66 kN.

The point loads are only transformed like this for the snow load, so it's essential to apply dead, wind, and live loads differently. This is why it's crucial to check out the article about how to apply loads to roofs for more information.

Calculating reaction forces is a crucial step in understanding the behavior of a scissor truss. The structure is statically determinate, which means we can use the 3 Equilibrium equations to calculate the support forces.

The first equilibrium equation, ∑H = 0, simplifies to A_H = 0, indicating that the horizontal reaction force at support A is zero.

The second equation, ∑V = 0, is used to calculate the vertical reaction forces at supports A and B. This equation reveals that A_V + B_V = 2 * 2.67 kN + 2 * 4.0 kN + 2.66 kN.

By solving the equation, we find that A_V = B_V = (2 * 2.67 + 2 * 4.0 + 2.66) / 2 kN = 8 kN.

The third equilibrium equation, ∑M = 0, confirms that the moment at support A is zero, or M_a = 0.

Custom timber trusses offer a world of design possibilities and unmatched structural integrity. They are the heart and soul of your timber framed space, not just pre-fabricated components.

Our team of experienced designers collaborates closely with you to transform your vision into a reality. We explore a range of factors that influence the design of your trusses, including shape, size and spacing, and visual impact.

The shape of your truss can greatly impact the aesthetic and functionality of your space. You have options like King post, Queen post, Hammerbeam, Scissor truss, each with its unique visual appeal and structural purpose.

Here are some common truss shapes and their characteristics:

By considering these factors, we can work with you to create a custom timber truss design that perfectly complements your architectural style and showcases the beauty of traditional joinery techniques.

Custom timber trusses offer a world of design possibilities and unmatched structural integrity. They're not just pre-fabricated components, but the heart and soul of your timber framed space.

Our team of experienced designers collaborates closely with you to transform your vision into a reality. We explore a range of factors that influence the design of your trusses.

The shape of your trusses is a crucial consideration. You have options like King post, Queen post, Hammerbeam, and Scissor truss, each offering a unique visual appeal and structural purpose. We'll guide you in selecting the perfect truss to achieve the desired aesthetic and functionality for each space.

The size and spacing of your trusses also play a crucial role in defining the scale and openness of your space. Our team considers factors like roof pitch, preferred style, and ceiling height to determine the optimal size and spacing for your custom trusses.

Timber trusses are more than just structural elements – they're a central design feature. We'll work with you to ensure your trusses seamlessly integrate with your chosen architectural style, whether it's a rustic lodge vibe, a modern minimalist aesthetic, or anything in between.

Here are some key factors to consider when designing your trusses:

The size of a truss is crucial to ensure it can hold up the roof's load. Structural engineers consider the load of the structure by consulting the residential building code.

To determine the load, engineers choose the sizes and materials for the frame and examine how the building will react to the roof load. This process helps them refine the materials and sizes for maximum performance.

Many timber trusses are assembled using exposed steel plates or mortise & tenon with wood pegs, which adds to the aesthetic appeal.