A roof truss is a structural framework of timbers, metal or steels designed to bridge the space above a room and to provide support for a roof. It is a structure with straight pieces forming triangles to support a load. The parts of the triangles (the roof truss types) are placed under tension and compression but do not bend.
A designing roof truss is quite challenging. We need to consider the right roof truss for our home. Some things to be considered when selecting roof truss type are the aesthetic conditions, functionality and the cost. Truss with triangular shape is widely used in roof construction.
However, there are always the positive and negative sides of each type. We need to select roof truss carefully because it will affect the final shape and slope of our roof. Here are some types of roof trusses you need to consider.
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Roof Truss Types and the Advantages
Many types of roof truss that can be used for your building. Each type has its own characteristics, design models and advantages. Here are some types of roof truss that are widely used along with the model design and the advantages.
Parallel Chord Roof Truss
This type is commonly used in a cathedral ceiling. It uses steel members to serve as bracing. Yet, it requires numerous and complex wood members, that is regarded as the disadvantage. Steel braces can reduce energy saving. The good point of this type is the simple lines of the parallel chord roof truss are interesting and appealing to the eye.
Raised Heel Roof Truss
Raised heel truss, or commonly known as energy-heel trusses provide greater energy efficiency. It is identical to a conventional truss where it is raised higher, with a heel that extends up from the top of the wall and elevates the truss at the building’s edges. By this, it can create vapor barrier and attic ventilation.
This truss is usually found in humid climates area. It requires a soffit siding and additional insulation work from the onset, which elevates construction costs. The raised heel roof truss can be used to span an area and provide full-depth attic space. Raised heel truss, however, is easy to build and save more money.
Scissor Roof Truss
A scissor roof truss is particularly found in cathedrals. It is used to create vaulted ceilings or more interesting ceiling shapes. It does not need a bearing beam. It uses lower chords that slope inward, instead of being horizontal.
The advantage of using this type is it does not leave that much space for insulation that makes its energy efficiency very poor. However, the vaulted ceiling makes it more appealing and it has more space in the attic.
Dropped Chord Roof Truss
The dropped chord variant is composed of a convention truss, with a secondary chord truss suspended below to help reduce uplift. Similar to the raised heel truss, this type also creates a vapor barrier creating great insulation characteristics. Vapor barriers need additional blocking and siding in the intersection of walls and ceilings, adding to the construction cost.
King Post Truss
This truss is usually made of wood, but it can also be made of a combination of steel and wood. This type is suitable for multiple types of houses, especially the smaller one. It usually is used for short spans. They are often used in extensions, garages, porches, and outbuildings. Many old buildings boast open, visible king post trusses.
Queen Post Truss
A queen post truss is a vertical upright with two triangles either side. It is designed to be a reliable, simple and versatile type of roof truss that we can use anytime. It offers a good span and has a simple design which makes it perfect for a wide range of establishment. However, queen post truss is replaced by fink truss. It is not commonly used any longer.
Fink Truss
Fink truss is a commonly used truss in residential homes and bridge architecture. It originated as a bridge truss although the use in the bridge is rare. It uses multiple diagonal members projecting down from the top at the end posts at a variety of angles.
These diagonal members extend to the bottom of each of the vertical members with the longest diagonal extending to the center vertical member. Many Fink trusses do not include a lower chord. A fink truss commonly uses ‘W’ shape between the chords. It is a very simple but efficient shape and can be used in all manner of projects.
Fan Truss
Fan truss is a very simple design and it is made out of steel. Sometimes, it forms a fink roof truss. The difference is that the top chords are split into smaller lengths, so the build can obtain purlin support.
Besides, we can get a medium span with this type, around 10-15 mm which is more than enough for most projects. Fan truss is characterized by the radiating lines of the king post and appended struts or the queen posts and appended struts.
North Light Roof Truss
The north light roof truss is suitable for the larger spans that go over 20m and get up to 30m. It is cheaper to add a truss that has wide, larger set of lattice girders that include support trusses. This type of truss is categorized as the oldest and most economical ones.
It also provides good ventilation and lasts longer roof life span due to its resistance. The advantages of north light roof truss are durability and versatility. If you are looking for durable and strong roof truss, this is the best idea. It can be used in industrial buildings or drawing rooms and general spaces that are very large.
Howe Truss
This particular truss is a combination of steel and wood. It makes the truss look elegant and appealing. Almost everything is made out of wood, yet the tension members of the vertical members are made out of steel to provide extra support and reliability.
One thing that makes Howe Truss special is it has a very wide span and it can cover anything from 6-30. This makes it versatile and very useful for a wide range of project types.
Conclusion
Those are some ideas of common roof truss types that usually used in building. Select one type which suitable you the most, in terms of function, budget and result. Consult with your trust builder or roof contractor to get the best suggest on your need.
They know what the best for your roof plans. They can make many adjustment using the basic roof trust type to suit the roof plan. For example they can build varies model of roof types like this.