One of the most important parts of any roof are the trusses. These beams provide the main support for the installation and create structural integrity for the entire building. A sound, weatherproof house covering installed by a professional roof company must start out with strong joists that provide the necessary support. Considering the essential role these studs play, it is important to understand how they are made and how they work.
What Is A Truss?
A roof truss is the framework that spans over a building, providing the necessary support on which the external top covering is attached. For these beams to be strong and sturdy, they must be carefully engineered to fit the specific span of the housetop and support the weight of all the material used. They must also support the force of rain, snow, wind, and other things that could add weight or tension to the structure. These ties also provide structural integrity to the spaces under them as well, combining with the external roofing material to create stable walls and housetops.
How Do Trusses Work?
Trusses are made from a number of different pieces, all of which work together to support and disperse the weight of the external installation. The dead weight of the housetop load is supported directly by two long and angular pieces called the top chords, while the bottom chord spans between them supporting the interior ceiling and attic weight. The top and bottom chords are secured together by shorter angular pieces called webs. The various parts of the studs are fastened together using nail plates, which are toothed metal plates compressed onto the ends of the truss sections to essentially nail them together.
Through natural compression and tension, webs support the top chord and transfer some of the weight to the bottom chord, allowing all parts of the truss to work collectively in supporting the roof while stabilizing the walls beneath it. Based on this essential relationship between the various beam parts, cutting webs to make space for HVAC vents or for any other reason is highly discouraged and is a common mistake made by some installers. It reduces the strength of the joists, creating weak spots in the roof and reducing the overall performance of the beams.
How Are Trusses Designed?
To gain the necessary stability and for the truss to work effectively to support the roof, these studs when installed by a roof company must be designed to support the load of each specific housetop. Load rates differ according to the length of the span of the housetop and the pitch. Longer spans, or those at lower pitches, require more support than shorter spans or those housetops with higher pitches. Considering this, it is essential for the roof company to use a joist that is appropriately sized and pitched for adequate support and also has enough webs to evenly distribute the load.
Trusses are available in many common and standard sizes that a roof company can purchase for their installation. When standard joists will not provide enough or the right support, it may be necessary to custom build the trusses for installation. In either case, the right ties are essential to ensure that the roof is structurally able to handle the weight of the materials and any other forces that may rest on this important top cover!