The construction of buildings has slowly changed over time. New options for building solid structures have emerged as technology advanced. Rafters were previously the most common element in completing the framework for the roof, but through the years, roof trusses became the preferred option by many. More than a dozen types of roof trusses emerged to suit different building styles and purposes. Knowledge about the different types of roof trusses is essential for any architect, construction worker, or individual working with design teams to construct a new building.
What is a roof truss?
A roof truss is a structural element that creates the frame for the roof of a building. It is composed of three main elements including top and bottom chords, including I-joists/ceiling joists, and webbing posts. A truss is a supporting structure that is made of interlocking jacks, joists, and rafters to form an A-frame to support roofs from the interior. Trusses may be built at the construction site, but they are more often purchased as completed components and shipped to the sites via freight trucks from the manufacturers.
Why roof trusses over the cut roof with rafters?
Roof trusses provide an alternative to rafters with certain advantages over them. They’re approximately thirty percent less expensive. they’re also made of more lightweight materials. Trusses are produced in mass quantities, adding convenience for construction crews, and they’re not as complicated to install. The use of trusses cuts down on the level of skill required for installation, and the amount of time it takes in labor for crews. Roof trusses are a more affordable option all the way around. Additionally, roof trusses better distribute the weight of the building onto the exterior walls, versus the interior walls, as is the case with the cut house with rafters. It opens up new stylistic opportunities for fewer load-bearing walls in a building, for open concept structures.
How many types of roof trusses are there?
According to Upgraded Home, there are fifteen different types of roof trusses. Some are similar but have different features to work with specific structural elements of a new building. If you’re not familiar with the different types of roof trusses, read on to learn everything there is to know about them, along with other information, to bring you up to speed about their advantages. Let’s explore the fifteen roof truss types, and their applications.
1. King Post Truss
The King post truss is a simple style of trusses constructed of two top chords and one lower chord. It gets its name from the central vertical post, or “king post,” with two webbing chords. The King Post Truss is used when making a roof for a garage, other small areas, or new additions to an existing structure. It’s best for spanning short distances. The disadvantage of this type of truss is that it can only be used for smaller buildings, although it is the least expensive truss to buy because it has the simplest design of them all.
2. Queen Post Truss
The Queen post truss is similar to the King Post stylistically. It is designed for supporting longer spans than the King Post. It is commonly used for making additions that span a larger distance, e.g., larger additions or garages. Unlike the King post, the Queen omits the centered vertical post and instead uses a straining beam to connect two vertical posts to better distribute weight across a larger area. Queen post trusses use more materials to construct. They’re a little more complicated and more expensive than a king post truss.
3. Scissor Truss
A scissor truss is constructed with sloped bottom chords. This style is used for homes or commercial buildings featuring high vaulted ceilings. The design of the truss allows for sloped ceilings for homes and other building types with open floor plans. This truss style allows for greater stylistic options with its more open concept that distributes the weight differently, to the exterior walls. Scissor trusses are among the more expensive types, often costing up to thirty percent more than other truss styles.
4. Gambrel Truss
The gambrel truss stands out from other styles because of its tall design. It is used to add vertical space to a building. Gambrel trusses are commonly used in buildings featuring a farmhouse style as they create a barn-shaped room. they’re placed at each end of the structure with a gable roof, closing off the attic space.
5. Fink Truss
A fink truss is most commonly used for the construction of homes. It’s easy to identify a fink truss because of the W shape formed by the webbing. The advantage of the fink truss is its ability to bear greater loads. It’s the type chosen when bigger loads are indicated in new construction or in adding spacious additions to a structure. The fink truss offers options for adding larger rooms to an existing building. Fink trusses also work for creating architecture with larger rooms.
6. Attic Truss
According to GAF, An attic truss goes beyond the traditional truss in making additional room under the roof for the addition of an attic. These unique trusses appear as the framing for the attic room. From a visual point of view, they have a similar appearance to queen-post trusses, but they differ because the post spacing is further apart. It’s essential to avoid deeming them the same because each serves a different purpose.
7. Fan Truss
A fan truss is a simple-styled truss, but it stands out because it features steel material. Other notable differences include a top chord separated into smaller lengths. The webbing combines elements of the fink and queen post trusses. It is used on buildings of medium size and offers the advantage of enhanced purlin support.
8. Flat Truss
A flat truss is an option when the goal is to provide high levels of support. The extra support capacity makes them the most useful for buildings with flat roofs. Most buildings featuring flat trusses are commercial.
9. Gable Truss
A Gable Truss has one bottom chord, two top chords, and several vertically set posts for webbing. Gable trusses get placed at the end of a gable roof. It is a standard roof style we mostly see in the construction of homes. The Gable style truss is one of the most expensive styles, commonly costing between thirty-five to fifty percent more than standard trusses.
10. Hip Truss
A hip truss is used for structures with roof slopes on all four sides, resulting in the shape of a pyramid. They’re ideal for roofs that receive large amounts of snow or are subject to high winds. The hip is a specialty truss for a hipped roof style. It’s one of the more expensive types because each hip truss must feature specific slope and ridge locations for each job. A hip truss is a reliable option. It outshines the gable truss under exceptional weather conditions. Multiple variations of the hip truss are available for creating unique and interesting architectural designs.
11. Mono Truss
A mono truss is half of a roof truss. This truss type is among the most versatile for creating unique roof styles. The mono truss fits in for the construction of roofs that allow more natural sunlight and visual space into the interiors of the buildings. We see mono trussed used in building extensions or when additional roof tiers get added to existing roofs. Mono trusses also make exceptional choices for sheds and garage construction.
12. Pratt Truss
Pratt trusses have been around since the middle 1800s. They are triangular trusses featuring vertical and diagonal elements that form a slope extending from the center to the outside. The vertical posts tension the design while the diagonally positioned posts offer compression. The Pratt truss is among the most economically priced and is often used in home construction. The Pratt truss features steel components. The strength of steel makes it among the most reliable, covering lengths between six to ten meters.
13. Howe Truss
Howe trusses feature components of steel and wood. The frame of a Howe truss is usually wood with vertical and tension members made of steel. The steel components add extra strength for load-bearing and distribution of the weight to exterior walls. A Howe truss is among the most reliable and durable truss types applicable for spans up to thirty meters. In addition to serving as building roof structuring, they’re also more commonly used in railroad bridges and bridge spans.
14. Parallel Chord Truss/Girder Truss
The Parallel chord truss is also known as a girder truss. These trusses come in a different shape than most other truss types. Their unique design forms a rectangular shape with top and bottom cords. The chords are long and straight with spacing and web reinforcement at intermediate locations. The Parallel Chord Truss features wood timber construction most often and is useful in providing exceptional support for purlins, rafters, and traditional trusses. They’re valued for their strength and durability and are used when longer spans are required. They’re the sensible choice for spanning distances without a central supporting post.
15. North Light Truss
North Light roof trusses are among the first styles ever designed. North Light trusses come in handy to get more natural lighting in the building. This style is standard for commercial building construction. The North Light roof truss enhances natural lighting. It delivers more natural light through glazing on the steepest pitch facing the North to the Northeast part of the building. It limits solar gain. The function of the truss is how the truss-style got its name. The style is appreciated because it reduces carbon emissions in industrial settings. The increase in natural lighting reduces the need for artificial lighting. Some architects also use North Light roof trusses in home construction. Additional ventilation structures might be needed as a part of the architecture of buildings using North Light roof trusses.
What are roof trusses made of?
According to Roofing Calculator, trusses usually consist of large segments of lumber. They’re generally 2×8 or 2×10 grade. Some of them have steel components. Some trusses get constructed of steel material. It usually requires a skilled carpenter with expert-level skills to build roof trusses on-site. Since it’s more expensive to do that, they’re commonly ordered to specifications from a mass-scale manufacturer and delivered as freight.
How to determine the type of roof truss in your home
Homeowners considering any structural addition to the home, or remodeling project should know what type of trusses currently exist. It’s essential to match to slope and shape of the existing structure to make the new addition fit into the design scheme. Unless you’re familiar with the various roof trusses, it can be hard to tell them apart for the untrained eye. The best way to determine what type of trusses are in the architecture of your home is to consider three elements. The shape of your roof gives you the first clue. There are three primary roof shapes, including gambrel, hip, and gable, which we’ve already discussed in the truss types. Homes with a hip roof usually have hip trusses, those with gable roofs, gable trusses, and those with gambrel shapes, gambrel trusses. The ceiling type can also give you a clue to the truss type. Vaulted or high-pitched ceilings may be scissor trusses, and those with an attic space, usually have attic trusses. Remember that the shape of the roof often gives you clues to the truss style.
There are fifteen different types of roof truss styles. Each has its distinct features and purposes within the construction industry. Even if you’re not involved with the hands-on work, anyone who plans to renovate or add on to a building must know the truss type to maintain consistency in the overall aesthetic of the structure.