Having a roof over one’s head is a basic human need, one in which we’ve improved upon through centuries of structural ingenuity. The roofing system has undergone a dramatic transformation since its early days of thatched roofs comprised of straw and reeds. Now, we’re talking about a roof truss, a complex structural element integral to the support of a roofing system.
In Structural Engineering, the name “truss” describes a triangular design. A joint framed structure that sustained the inclined, vertical or horizontal loads. A truss consist of angles, channels, plates and eye bars. It is a framework, typically consisting of rafters, posts, and struts, supporting a roof, bridge or other structure. You will find them supporting the roofs of auditoriums, cinema halls, stadiums, railways, stations, airports and others.
Anatomy of Roof Truss
When you get down to the basics of a roof truss, you’ll notice that it’s made up of three parts: top chords, bottom chords, and web bracing. The framework of the truss is also made up of three elements: posts, struts, and rafters. Because the entire framework is placed under strain and not supposed to bend as a result, the components of a roof truss are ultimately defined by things like load weight and spacing.
A roof truss must be made of similarly sturdy and strong material because its purpose is to aid in the support and reinforcement of the roof. A roof truss is often made of wood or metal, and it provides strength as well as the flexibility to be altered and changed relatively easily.
By the same token, a roof truss must be lightweight. A modern roof truss is made up of multiple discrete lightweight parts that are meant to support a big load while not being too heavy to carry. Fundamentally, this makes the task of building a roof truss a daunting one, one that is labor-intensive and demanding in terms of linking various devices to form the framework. A roof truss, despite its time-consuming construction, is more cost-effective in the long run since it insures the roof’s lifespan.
6 Common Types of Roof Trusses
Since there are different types and variation of roof trusses, let’s find out which ones are the most popular and what distinct features they have.
King Post Truss
Common uses: Home additions, garage construction, short-span projects
Span: 5 to 8 meters
King post trusses are the most basic type of truss. It uses the fewest truss members – two top chords, one bottom chord, a central vertical post called the king post, and two webbing chords.
Because king post trusses are made with few materials and a simple design, they come at a lower price point than many other trusses. However, this also means that king post trusses cannot span long distances, so they are better suited for smaller-scale projects.
Queen Post Truss
Common uses: Residential home construction, home additions
Span: 8 to 12 meters
Queen post trusses are similar to king post trusses in that they have a simple, yet sturdy design. Instead of having one king post in the center, this type of truss will have two queen posts that are connected by a straining beam.
The additional posts in a queen post truss makes them slightly more expensive than a king post truss.
The two vertical queen posts allow queen post trusses to span greater spans than king post trusses, which means they can be used for larger projects.
Fink Truss
Common uses: Residential home construction
Span: Up to 14 meters
Fink trusses are the most common truss seen in residential roof construction. The webbing in fink trusses has a ‘W’ shape, giving them a great load-carrying capacity. The position of the webbing allows for some storage space, and can accommodate things like water tanks if need be.
They are also considered one of the most cost-effective roof trusses available, especially because they can span far distances.
Attic Truss
Common uses: Residential home construction projects that require an attic or additional loft living space
Span: Up to 25 meters
One downside to many trusses is that the webbing can often limit attic space. This can be a dealbreaker for homeowners looking for additional storage or living space. Luckily, there are attic trusses, which are built to allow for attic space.
Attic trusses look similar to queen post trusses, but the two vertical posts are spaced further apart to allow for attic space. The wider the building structure is, the bigger the attic space will be. The steeper the roof pitch is, the taller the attic ceiling will be.
Scissor Truss
Common uses: Residential home construction projects that require vaulted ceilings
Span: Up to 22 meters
Scissor trusses make it possible to create vaulted ceilings. The bottom chords of scissor trusses are sloped, creating the dramatic ceiling in the room below. Scissor trusses combine the speed and convenience of using pre-engineered wood trusses, while still getting the aesthetic benefit of high ceilings.
You can install scissor trusts in one part of your home, and use other types of trusses in other areas of your home where you don’t want vaulted ceilings. What’s great is that from the outside, your roof will look uniform, even if one area has high ceilings.
Keep in mind though, scissor trusses do come at a higher cost than other types of trusses – sometimes up to 30% more than standard truss types.
Gable Truss
Common uses: Residential gable roof construction
Span: Varies depending on roof design
Gable trusses are usually used in combination with other types of trusses. The gable truss serves as the ‘end cap’ for the roof. They have two top chords, one bottom chord, and multiple vertical posts. Gable trusses are built on each end of the roof framework to support roof sheathing.
Gable trusses will cost anywhere from 25% to 50% more than standard-style trusses.
Benefits of Roof Truss
For a variety of reasons, roof trusses have become more common than rafters in recent years. The fact that trusses are over 30% cheaper than rafters is probably the most important reason for their popularity.
They are made of lighter materials and can be produced and acquired in big quantities, lowering the cost. Trusses also have cheaper labor expenses because they don’t require the professional labor of an expert carpenter. You may anticipate to pay anything from £20 to £300 per truss, according to HomeAdvisor.
Another significant benefit of truss systems is that the weight of the roof is distributed to the outer walls of the home rather than the inner walls. Home builders may simply design the wildly popular open-concept living rooms with few to no interior load-bearing barriers.
It also makes it easier for homeowners to knock down interior walls in the future as part of restorations and house improvements.
Conclusion
Now that you know all about what goes into the anatomy of a roof, you know what to look for when the time comes for a replacement. If the shingles of your roof look old, worn out or damaged, you need to replace your roof as soon as possible to avoid further damage.
In such a case, CMQ Consulting Engineers has you covered. Contact us now to start your roofing project with us.
