Roof Trusses and Their Types

Roof Trusses are triangular structures in the roof of a building. They are built to provide support and stability to the roof. The basic purpose of the roof truss is to distribute the weight of the roof away from the exterior walls of the structure you are building. For residential designs, the trusses are usually made of wood and for commercial purposes, steel is preferred.

Roof Truss Benefits

Roof trusses have been used in buildings for hundreds of years. They allow engineers to create huge spaces with the minimum amount of materials. Trusses are strong structures and they have different types used for different purposes.

Types of Roof Trusses

Even though roof trusses are always triangular, there are several types of trusses and each serves a different purpose as mentioned below:

  1. King Post Truss
    A king post is a vertical post used mostly in architectural or bridge designs situated at the center which takes tension for the purpose of supporting a beam below from a truss apex situated above. A King post truss consists of a tie beam, two inclined principal rafters, a king post, two struts, and a ridge beam.

    A king post truss is not only used for its functionality but also adds beauty to a building. Apart from buildings, the king post truss is also used in aircraft.
  2. Queen Post Truss
    The Queen post truss is pitched roof support. It uses two posts laid vertically with the rafters and a tie-beam connected between them. The Queen post truss consists of two main Queen posts, a tie beam, two struts, two rafters, straining sills, straining beams, and a couple of purlins. A queen post truss is most suitable for 8-12 meters of the roof and usually made from timber or steel.

    Compared to a king post truss, a queen post truss is much simpler and lighter in weight. A queen post truss comes in handy when large areas need to be covered. It can be made to fit almost any slope or size of a roof and costs quite less. Just like a king post truss, a queen post truss is also used to give some striking design to a house.

    A queen post truss also comes in a modified form and the difference between the normal and modified queen-post truss is that the latter has multiple added panels on each side.
  3. Room-in-Attic Truss
    The name room-in-attic truss is self-explanatory. They are used to create living spaces in the attics. The bottom cord of this truss is increased for live loads just like the floor systems you see in a residential space. These trusses are usually used if you want to add a living or storage space without adding a floor to your building.
  4. Coffer or Tray Truss
    A coffer or tray truss is a pitched truss that can be a sloping or non-sloping vertical ceiling detail in the interior. Tray trusses are mainly used for aesthetic purposes rather than practical purposes that is why they are most suitable for the dining room, living room, or kitchen.
  5. Barrel Vault Truss
    Barrel Vault trusses are usually used in cellars or sometimes long hallways. Just like the name suggests, it makes up a barrel-shaped ceiling. It uses several small pieces of wood that are framed together to create a cylindrical appearance in the ceiling.

    Just like a tray truss, it is used as a decorative type of truss. The main characteristics of a Barrel Vault truss are that it keeps the room cool and requires relatively low maintenance.
  6. ClearStory Truss
    A clearstory truss is mostly used in energy-efficient buildings and used to allow fresh air and light into the room. It consists of a high wall between two sides that are sloping. It also features some small and narrow windows.
  7. Mono Truss
    A mono truss is a single sloped truss where one slope forms a right-angled triangle. These trusses are usually used for the extension of an existing roof but they can also be used for sheds or garages. The main advantages of a mono truss are that they allow sufficient sunlight and proper drainage. They are also relatively cheap.
  8. Fink Truss
    A fink truss is formed of a double V web and is mostly used in pedestrian bridges. It can also be used in residential homes. A fink truss can come in a double or triple fink, in which the V configuration is doubled and tripled respectively.
  9. Howe Truss
    A Howe truss is named after its original designer William Howe. They were designed in 1840 and consist of an M web configuration. The most common use for a Howe truss is railroad bridges.

    If a Howe truss is built with an extra pair of vertical posts diagonal on both sides, it becomes a double Howe truss.
  10. Double Cantilever
    A Double Cantilever truss is mostly used in high-rise buildings. This truss is used to add height to a building and it also allows light inside the building and gives the building a sophisticated look. It uses two horizontal beams that are fixed at one end. The beams extend afar from the load they are bearing.
  11. Hip Girder Truss
    Hip Girder Trusses are pitch trusses with a trimmed or flat apex to support more loads. They are strong trusses that are resistant to strong winds and hurricanes.
  12. Polynesian Truss
    A Polynesian truss as the name suggests is mostly found in the Asia-Pacific region in the Polynesian style. It is designed with an increased slope and a double-symmetrical pitch at the top chord.

    These are a few types of trusses that are used in everyday constructions. All these trusses can be modified according to the needs of each individual. Trusses have been added to roofs for centuries and their significance cannot be ignored.

    This is the reason that they have survived the test of time and there hasn’t been a better alternative introduced when designing the roofs of buildings or bridges either.