Fact Checked

What Is a Truss Frame?

C.B. Fox
C.B. Fox

A truss frame is used in a variety of structures to help provide strength and support. There are many different types of these frames, but all make use of triangular sections which are connected together at the nodes, or corners of the triangle. Trusses are usually arranged in flat planes but can be connected with other planes to form three dimensional shapes, usually rectangular boxes or cubes. It is also possible for a structure to make use of a three-dimensional truss frame, which is usually stronger and more stable than a two-dimensional frame.

No matter what the shape of the final building or structure, each truss frame used to support it is made up of a series of triangular wedges. By arranging the triangular pieces in different ways and by using triangles of different sizes, engineers are able to create truss frames as supports for triangular, rectangular, or even arch-shaped sections of a building. The triangle is essential to the truss frame because this shape is able to support a great amount of weight and stress without breaking or losing its shape.

A roof truss provides support for a roof.
A roof truss provides support for a roof.

Buildings and bridges commonly make use of the truss frame. This design has been used in buildings for hundreds of years and is still the most commonly used design for roofing in many parts of the world. In modern architecture, wooden trusses are still frequently used, though they often use metal nodes, which give the truss additional strength. Modern bridges also use the truss frame, though all the components of the frames are usually made out of metal instead of wood.

Depending on the desired shape of the structure, a wide variety of truss frames may be used, though simple, or common trusses, are often designed in triangular shapes. These designs are seen frequently in the roofs of houses and can be adjusted to give the roof more or less pitch. Truss floors are also common and can be made out of a series of linear truss frames or out of a three-dimensional truss frame that uses a three-dimensional shape, usually a tetrahedron or pyramid, as the framework of the truss. Long, rectangular truss frames, the most common of these being the Pratt truss, are also frequently used in a variety of different structures, including truss bridges. Bowstring trusses, made of triangles of different heights that are capped with an arced board, can also be used to create rounded edges in structures.

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Discussion Comments


@MrsPramm - Well, there's a couple of different reasons people use the truss frame shape. Firstly, it can be quite strong and it's a standard for engineering bridges and things because of this. Most bridges will use steel trusses somewhere along their length.

Also, with houses, using that kind of triangle shape can make sure that rain and snow won't end up weighing down the roof. If you look at the roofs of people in different climates, you'll see the sides of the triangles in the truss frame get steeper and steeper depending on how much snow they get. In dry regions, they might just have a flat roof.


@clintflint - We'd do the same thing, but we'd use opaque plastic and use it to protect seedlings from the sun when it got too strong during the day. Really good to keep the birds out too.

I guess it's just an easy shape to put together and that's why houses and things often use it.


My dad always used to call our little cloches "truss frames". They were lightweight covers for seedlings and plants which might be vulnerable to frost. We usually would just make them in that triangle shape, so I guess that's why he called them that.

Basically you just take whatever you've got lying around, like plastic pipe or wood and tie it together into a shape like a roof, with a triangle at either end, attached by poles as long as you want them. A wood truss looks nicer, but we found using pipes was more efficient.

Then you cover it with clear, heavy plastic sheeting and put it over whatever plants need protection.

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    • A roof truss provides support for a roof.
      By: Omika
      A roof truss provides support for a roof.