Roof trusse is a structural framework of timbers designed to bridge the space above a room and to provide support for a roof. Trusses usually occur at regular intervals, linked by longitudinal timbers such as purlins. The space between each truss is known as a bay.
Rafters have a tendency to flatten under gravity, thrusting outwards on the walls. For larger spans and thinner walls, this can topple the walls. Pairs of opposing rafters were thus initially tied together by a horizontal tie beam, to form coupled rafters. But such roofs were structurally weak, and lacking any longitudinal support, they were prone to racking, a collapse resulting from horizontal movement. Timber roof trusses were a later, medieval development. A roof truss is cross-braced into a stable, rigid unit. Ideally, it balances all of the lateral forces against one another, and thrusts only directly downwards on the supporting walls. In practice, lateral forces may develop;
A roof truss consists of top chords, bottom chords, internal web members and steel connector plates at all junctions to connect the timbers together and the combination of timber and plates support the roof loadings throughout the truss and down into the load bearing supports below.
Timber roof trusses can be used to frame a wide range of roofs, both cold and warm, and a wide range of super structures including timber, masonry and steel frame. There’s a variety of different roof trusses and they vary in terms of their shape, size and use and it can be overwhelming trying to work out which type you need for your project. As a roof truss manufacturer, we want to help make it clear what the most popular different types of roof trusses are and what they are typically used for.
We design all types of roof trusses, some examples are fink trusses, attic trusses, scissor trusses, raised tie trusses and mono trusses to Glulam feature trusses, oak feature trusses and kerto feature trusses.
The type of roof truss you choose for your building project can have a major impact on the final type of roof. Whether you’re building homes, multi-family projects, or large agricultural structures, roof trusses are integral to the structure, style, and cost of your build. With that in mind, it’s important to choose the right type of roof truss to suit your project and your project’s budget. Here are a few of the most common types of roof trusses that might be perfect for your build:
A variety of the trusses shown above fit into the common or gable truss category, including the King Post, Queen Post, Howe, and Double Howe trusses. All four of these trusses are used to form a gable roof, also known as a pitched or peaked roof, and one of the most common roof options in the US. The difference in each of these trusses has to do with the webbing in the truss itself. As you might imagine, trusses like the Howe offer more support than a King Post, and thus can be used for larger buildings that need more support.
Another very common roof type, the hip truss is used to create a hip roof, which has slopes on all four sides that come to meet at a point in the center of the roof. Hip trusses are particularly useful for high wind and snowy areas, as they are more stable than gable roofs. Like the gable truss category, there are a number of unique hip truss variations, used to create different architectural styles.
This type of truss is best known for creating the vaulted ceilings that today’s homeowners love. Instead of horizontal lower chords, a scissor roof truss has lower chords that slope up, creating the peak for a vaulted ceiling.
Convenient for buildings like garages and sheds that need additional storage space, attic trusses, also known as room-in-attic trusses, form both the ceiling and the floor truss for a room within a building’s attic. These roof trusses come with support webs designed to frame the walls of the room. While these are most commonly used for structures with storage space, they can also be manufactured for homes.
A mono truss is essentially just one half of a full truss. These are very versatile and can be used to build a roof that allows for more sunlight and visual space. They are often used in sheds and garages, as well as to create additional roof tiers and extensions to an existing roof.
Similar to the Double Howe Truss, the North Light Roof Truss features a wide set of web trusses that form triangles within the larger truss itself. A popular choice for open floor plan homes, North Light Trusses are an old and economical type of truss that can span very large spaces, like industrial buildings and open concept homes.
As you might expect, a flat truss is designed for flat roofs. They’re built similarly to floor trusses, with a great deal of support, since they don’t feature any slope to shed precipitation or help bear a load. Flat roof trusses are primarily used in commercial applications.
The gambrel truss is most commonly associated with barns, but it is also used in a variety of homes, especially now that the farmhouse style is increasing in popularity. A gambrel truss is designed to support a wide span and can add to the vertical space in a building because of its unique, tall construction.
The last truss we’ll cover today is called a raised heel truss. Since these roof trusses are raised slightly higher than other types of roof trusses, they allow for simplified ventilation and plenty of room for insulation. This makes the raised heel truss a go-to choice for energy-efficient buildings.