What Is a Scissor Truss?

A scissor truss creates dramatic interior ceilings and provides support and stability to buildings, especially for roofs that are exposed to extreme weather or houses located on lots with shifting soils. Learn what a scissor truss is and whether it’s the right choice for your new home.

What Is a Scissor Truss?

A scissor truss (also known as a Cathedral truss) is made with double bottom chords that meet in the middle of the truss creating a “scissor,” or an inverted-V shape underneath.

Scissor trusses are usually used in residential buildings to support a sloped ceiling or a high vaulted roof with a span of up to 78 feet. 

The Cost of a Scissor Truss

Scissor trusses cost more than typical trusses— ranging between $45 to $500 each. This is about 15% to 30% more than the average truss price.

The Pros and Cons of Scissor Trusses

Like all roof trusses, scissor trusses come with advantages as well as disadvantages.

Pros of a Scissor Truss

• Low installation cost: Some roof trusses need framing support to ensure that the truss has the desired pitch. But scissor trusses eliminate the need for additional support, which can result in significant savings.

• Great design: The vaulted ceiling provides extra headroom and gives a sense of openness to your home.

• Easy to install: Because they are prefabricated, scissor roof trusses are easy to install for your roof replacement project.

• Customizable: Most truss or roof fabrication manufacturers offer customized designs to increase or decrease the size or slope of a scissor truss to perfectly fit the specifications, which can be installed with barely any modifications on-site.

• Easy to maintain or repair: Water damage is the most likely issue, but a typical scissor truss prevents water from accumulating and causing damage or mold, making it less susceptible to structural damage over time. Not to mention, scissor truss roofs are easy to maintain because they have fewer structural components than other truss types.

Cons of a Scissor Truss

• Difficult to insulate: Scissor trusses are more challenging to insulate than any typical roof truss because of the tight access at the narrow end of the truss. That makes it hard to air-seal the ceiling near the outside wall. It also restricts the available space to add effective insulation and attic-venting detail at the roof’s edge.

• Tight access to eaves: Compared to typical roof trusses, scissor trusses provide narrow access at the eaves. Construction workers usually find it hard to crawl to the edge of the attic to perform work. Even inspection for potential problems won’t be as straightforward—consult with a roof inspector near you for more information.

How Are Scissor Trusses Made?

Trusses support weight by transferring the loads to the building walls, which play a key role in constructing the ceilings of a building. Truss engineers can create customized trusses to match your design with almost no on-site alterations required.

Factories that manufacture prefab trusses use advanced software to design the trusses. They provide the span of the roof and the desired roof pitch, leaving the software to do the rest automatically. 

Can You Mix Scissor Trusses With Other Trusses?

Many roofing contractors combine different truss types to provide better coverage of the roof area. You can install a scissor truss in one part of your home and use other types of trusses in other areas.

Your roof will look uniform from the outside, even if one area has high ceilings, but the design of different trusses makes the structure more demanding and might cost more than the typical truss installation. Consult with a local roofing professional for more information.